Merge branch 'virtio-next' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux
Pull virtio changes from Rusty Russell:
"New workflow: same git trees pulled by linux-next get sent straight to
Linus. Git is awkward at shuffling patches compared with quilt or mq,
but that doesn't happen often once things get into my -next branch."
* 'virtio-next' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux: (24 commits)
lguest: fix occasional crash in example launcher.
virtio-blk: Disable callback in virtblk_done()
virtio_mmio: Don't attempt to create empty virtqueues
virtio_mmio: fix off by one error allocating queue
drivers/virtio/virtio_pci.c: fix error return code
virtio: don't crash when device is buggy
virtio: remove CONFIG_VIRTIO_RING
virtio: add help to CONFIG_VIRTIO option.
virtio: support reserved vqs
virtio: introduce an API to set affinity for a virtqueue
virtio-ring: move queue_index to vring_virtqueue
virtio_balloon: not EXPERIMENTAL any more.
virtio-balloon: dependency fix
virtio-blk: fix NULL checking in virtblk_alloc_req()
virtio-blk: Add REQ_FLUSH and REQ_FUA support to bio path
virtio-blk: Add bio-based IO path for virtio-blk
virtio: console: fix error handling in init() function
tools: Fix pthread flag for Makefile of trace-agent used by virtio-trace
tools: Add guest trace agent as a user tool
virtio/console: Allocate scatterlist according to the current pipe size
...
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index f9acddd..c8af429 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -656,7 +656,6 @@
depends on 64BIT && EXPERIMENTAL
select VIRTUALIZATION
select VIRTIO
- select VIRTIO_RING
select VIRTIO_CONSOLE
help
Enabling this option adds support for virtio based paravirtual device
diff --git a/arch/x86/lguest/Kconfig b/arch/x86/lguest/Kconfig
index 6e121a2..7872a33 100644
--- a/arch/x86/lguest/Kconfig
+++ b/arch/x86/lguest/Kconfig
@@ -4,7 +4,6 @@
depends on X86_32
select VIRTUALIZATION
select VIRTIO
- select VIRTIO_RING
select VIRTIO_CONSOLE
help
Lguest is a tiny in-kernel hypervisor. Selecting this will
diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index c0bbeb4..0bdde8f 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -14,6 +14,9 @@
#define PART_BITS 4
+static bool use_bio;
+module_param(use_bio, bool, S_IRUGO);
+
static int major;
static DEFINE_IDA(vd_index_ida);
@@ -23,6 +26,7 @@
{
struct virtio_device *vdev;
struct virtqueue *vq;
+ wait_queue_head_t queue_wait;
/* The disk structure for the kernel. */
struct gendisk *disk;
@@ -51,53 +55,244 @@
struct virtblk_req
{
struct request *req;
+ struct bio *bio;
struct virtio_blk_outhdr out_hdr;
struct virtio_scsi_inhdr in_hdr;
+ struct work_struct work;
+ struct virtio_blk *vblk;
+ int flags;
u8 status;
+ struct scatterlist sg[];
};
-static void blk_done(struct virtqueue *vq)
+enum {
+ VBLK_IS_FLUSH = 1,
+ VBLK_REQ_FLUSH = 2,
+ VBLK_REQ_DATA = 4,
+ VBLK_REQ_FUA = 8,
+};
+
+static inline int virtblk_result(struct virtblk_req *vbr)
{
- struct virtio_blk *vblk = vq->vdev->priv;
+ switch (vbr->status) {
+ case VIRTIO_BLK_S_OK:
+ return 0;
+ case VIRTIO_BLK_S_UNSUPP:
+ return -ENOTTY;
+ default:
+ return -EIO;
+ }
+}
+
+static inline struct virtblk_req *virtblk_alloc_req(struct virtio_blk *vblk,
+ gfp_t gfp_mask)
+{
struct virtblk_req *vbr;
- unsigned int len;
- unsigned long flags;
- spin_lock_irqsave(vblk->disk->queue->queue_lock, flags);
- while ((vbr = virtqueue_get_buf(vblk->vq, &len)) != NULL) {
- int error;
+ vbr = mempool_alloc(vblk->pool, gfp_mask);
+ if (!vbr)
+ return NULL;
- switch (vbr->status) {
- case VIRTIO_BLK_S_OK:
- error = 0;
- break;
- case VIRTIO_BLK_S_UNSUPP:
- error = -ENOTTY;
- break;
- default:
- error = -EIO;
+ vbr->vblk = vblk;
+ if (use_bio)
+ sg_init_table(vbr->sg, vblk->sg_elems);
+
+ return vbr;
+}
+
+static void virtblk_add_buf_wait(struct virtio_blk *vblk,
+ struct virtblk_req *vbr,
+ unsigned long out,
+ unsigned long in)
+{
+ DEFINE_WAIT(wait);
+
+ for (;;) {
+ prepare_to_wait_exclusive(&vblk->queue_wait, &wait,
+ TASK_UNINTERRUPTIBLE);
+
+ spin_lock_irq(vblk->disk->queue->queue_lock);
+ if (virtqueue_add_buf(vblk->vq, vbr->sg, out, in, vbr,
+ GFP_ATOMIC) < 0) {
+ spin_unlock_irq(vblk->disk->queue->queue_lock);
+ io_schedule();
+ } else {
+ virtqueue_kick(vblk->vq);
+ spin_unlock_irq(vblk->disk->queue->queue_lock);
break;
}
- switch (vbr->req->cmd_type) {
- case REQ_TYPE_BLOCK_PC:
- vbr->req->resid_len = vbr->in_hdr.residual;
- vbr->req->sense_len = vbr->in_hdr.sense_len;
- vbr->req->errors = vbr->in_hdr.errors;
- break;
- case REQ_TYPE_SPECIAL:
- vbr->req->errors = (error != 0);
- break;
- default:
- break;
- }
+ }
- __blk_end_request_all(vbr->req, error);
+ finish_wait(&vblk->queue_wait, &wait);
+}
+
+static inline void virtblk_add_req(struct virtblk_req *vbr,
+ unsigned int out, unsigned int in)
+{
+ struct virtio_blk *vblk = vbr->vblk;
+
+ spin_lock_irq(vblk->disk->queue->queue_lock);
+ if (unlikely(virtqueue_add_buf(vblk->vq, vbr->sg, out, in, vbr,
+ GFP_ATOMIC) < 0)) {
+ spin_unlock_irq(vblk->disk->queue->queue_lock);
+ virtblk_add_buf_wait(vblk, vbr, out, in);
+ return;
+ }
+ virtqueue_kick(vblk->vq);
+ spin_unlock_irq(vblk->disk->queue->queue_lock);
+}
+
+static int virtblk_bio_send_flush(struct virtblk_req *vbr)
+{
+ unsigned int out = 0, in = 0;
+
+ vbr->flags |= VBLK_IS_FLUSH;
+ vbr->out_hdr.type = VIRTIO_BLK_T_FLUSH;
+ vbr->out_hdr.sector = 0;
+ vbr->out_hdr.ioprio = 0;
+ sg_set_buf(&vbr->sg[out++], &vbr->out_hdr, sizeof(vbr->out_hdr));
+ sg_set_buf(&vbr->sg[out + in++], &vbr->status, sizeof(vbr->status));
+
+ virtblk_add_req(vbr, out, in);
+
+ return 0;
+}
+
+static int virtblk_bio_send_data(struct virtblk_req *vbr)
+{
+ struct virtio_blk *vblk = vbr->vblk;
+ unsigned int num, out = 0, in = 0;
+ struct bio *bio = vbr->bio;
+
+ vbr->flags &= ~VBLK_IS_FLUSH;
+ vbr->out_hdr.type = 0;
+ vbr->out_hdr.sector = bio->bi_sector;
+ vbr->out_hdr.ioprio = bio_prio(bio);
+
+ sg_set_buf(&vbr->sg[out++], &vbr->out_hdr, sizeof(vbr->out_hdr));
+
+ num = blk_bio_map_sg(vblk->disk->queue, bio, vbr->sg + out);
+
+ sg_set_buf(&vbr->sg[num + out + in++], &vbr->status,
+ sizeof(vbr->status));
+
+ if (num) {
+ if (bio->bi_rw & REQ_WRITE) {
+ vbr->out_hdr.type |= VIRTIO_BLK_T_OUT;
+ out += num;
+ } else {
+ vbr->out_hdr.type |= VIRTIO_BLK_T_IN;
+ in += num;
+ }
+ }
+
+ virtblk_add_req(vbr, out, in);
+
+ return 0;
+}
+
+static void virtblk_bio_send_data_work(struct work_struct *work)
+{
+ struct virtblk_req *vbr;
+
+ vbr = container_of(work, struct virtblk_req, work);
+
+ virtblk_bio_send_data(vbr);
+}
+
+static void virtblk_bio_send_flush_work(struct work_struct *work)
+{
+ struct virtblk_req *vbr;
+
+ vbr = container_of(work, struct virtblk_req, work);
+
+ virtblk_bio_send_flush(vbr);
+}
+
+static inline void virtblk_request_done(struct virtblk_req *vbr)
+{
+ struct virtio_blk *vblk = vbr->vblk;
+ struct request *req = vbr->req;
+ int error = virtblk_result(vbr);
+
+ if (req->cmd_type == REQ_TYPE_BLOCK_PC) {
+ req->resid_len = vbr->in_hdr.residual;
+ req->sense_len = vbr->in_hdr.sense_len;
+ req->errors = vbr->in_hdr.errors;
+ } else if (req->cmd_type == REQ_TYPE_SPECIAL) {
+ req->errors = (error != 0);
+ }
+
+ __blk_end_request_all(req, error);
+ mempool_free(vbr, vblk->pool);
+}
+
+static inline void virtblk_bio_flush_done(struct virtblk_req *vbr)
+{
+ struct virtio_blk *vblk = vbr->vblk;
+
+ if (vbr->flags & VBLK_REQ_DATA) {
+ /* Send out the actual write data */
+ INIT_WORK(&vbr->work, virtblk_bio_send_data_work);
+ queue_work(virtblk_wq, &vbr->work);
+ } else {
+ bio_endio(vbr->bio, virtblk_result(vbr));
mempool_free(vbr, vblk->pool);
}
+}
+
+static inline void virtblk_bio_data_done(struct virtblk_req *vbr)
+{
+ struct virtio_blk *vblk = vbr->vblk;
+
+ if (unlikely(vbr->flags & VBLK_REQ_FUA)) {
+ /* Send out a flush before end the bio */
+ vbr->flags &= ~VBLK_REQ_DATA;
+ INIT_WORK(&vbr->work, virtblk_bio_send_flush_work);
+ queue_work(virtblk_wq, &vbr->work);
+ } else {
+ bio_endio(vbr->bio, virtblk_result(vbr));
+ mempool_free(vbr, vblk->pool);
+ }
+}
+
+static inline void virtblk_bio_done(struct virtblk_req *vbr)
+{
+ if (unlikely(vbr->flags & VBLK_IS_FLUSH))
+ virtblk_bio_flush_done(vbr);
+ else
+ virtblk_bio_data_done(vbr);
+}
+
+static void virtblk_done(struct virtqueue *vq)
+{
+ struct virtio_blk *vblk = vq->vdev->priv;
+ bool bio_done = false, req_done = false;
+ struct virtblk_req *vbr;
+ unsigned long flags;
+ unsigned int len;
+
+ spin_lock_irqsave(vblk->disk->queue->queue_lock, flags);
+ do {
+ virtqueue_disable_cb(vq);
+ while ((vbr = virtqueue_get_buf(vblk->vq, &len)) != NULL) {
+ if (vbr->bio) {
+ virtblk_bio_done(vbr);
+ bio_done = true;
+ } else {
+ virtblk_request_done(vbr);
+ req_done = true;
+ }
+ }
+ } while (!virtqueue_enable_cb(vq));
/* In case queue is stopped waiting for more buffers. */
- blk_start_queue(vblk->disk->queue);
+ if (req_done)
+ blk_start_queue(vblk->disk->queue);
spin_unlock_irqrestore(vblk->disk->queue->queue_lock, flags);
+
+ if (bio_done)
+ wake_up(&vblk->queue_wait);
}
static bool do_req(struct request_queue *q, struct virtio_blk *vblk,
@@ -106,13 +301,13 @@
unsigned long num, out = 0, in = 0;
struct virtblk_req *vbr;
- vbr = mempool_alloc(vblk->pool, GFP_ATOMIC);
+ vbr = virtblk_alloc_req(vblk, GFP_ATOMIC);
if (!vbr)
/* When another request finishes we'll try again. */
return false;
vbr->req = req;
-
+ vbr->bio = NULL;
if (req->cmd_flags & REQ_FLUSH) {
vbr->out_hdr.type = VIRTIO_BLK_T_FLUSH;
vbr->out_hdr.sector = 0;
@@ -172,7 +367,8 @@
}
}
- if (virtqueue_add_buf(vblk->vq, vblk->sg, out, in, vbr, GFP_ATOMIC)<0) {
+ if (virtqueue_add_buf(vblk->vq, vblk->sg, out, in, vbr,
+ GFP_ATOMIC) < 0) {
mempool_free(vbr, vblk->pool);
return false;
}
@@ -180,7 +376,7 @@
return true;
}
-static void do_virtblk_request(struct request_queue *q)
+static void virtblk_request(struct request_queue *q)
{
struct virtio_blk *vblk = q->queuedata;
struct request *req;
@@ -203,6 +399,34 @@
virtqueue_kick(vblk->vq);
}
+static void virtblk_make_request(struct request_queue *q, struct bio *bio)
+{
+ struct virtio_blk *vblk = q->queuedata;
+ struct virtblk_req *vbr;
+
+ BUG_ON(bio->bi_phys_segments + 2 > vblk->sg_elems);
+
+ vbr = virtblk_alloc_req(vblk, GFP_NOIO);
+ if (!vbr) {
+ bio_endio(bio, -ENOMEM);
+ return;
+ }
+
+ vbr->bio = bio;
+ vbr->flags = 0;
+ if (bio->bi_rw & REQ_FLUSH)
+ vbr->flags |= VBLK_REQ_FLUSH;
+ if (bio->bi_rw & REQ_FUA)
+ vbr->flags |= VBLK_REQ_FUA;
+ if (bio->bi_size)
+ vbr->flags |= VBLK_REQ_DATA;
+
+ if (unlikely(vbr->flags & VBLK_REQ_FLUSH))
+ virtblk_bio_send_flush(vbr);
+ else
+ virtblk_bio_send_data(vbr);
+}
+
/* return id (s/n) string for *disk to *id_str
*/
static int virtblk_get_id(struct gendisk *disk, char *id_str)
@@ -360,7 +584,7 @@
int err = 0;
/* We expect one virtqueue, for output. */
- vblk->vq = virtio_find_single_vq(vblk->vdev, blk_done, "requests");
+ vblk->vq = virtio_find_single_vq(vblk->vdev, virtblk_done, "requests");
if (IS_ERR(vblk->vq))
err = PTR_ERR(vblk->vq);
@@ -477,6 +701,8 @@
struct virtio_blk *vblk;
struct request_queue *q;
int err, index;
+ int pool_size;
+
u64 cap;
u32 v, blk_size, sg_elems, opt_io_size;
u16 min_io_size;
@@ -506,10 +732,12 @@
goto out_free_index;
}
+ init_waitqueue_head(&vblk->queue_wait);
vblk->vdev = vdev;
vblk->sg_elems = sg_elems;
sg_init_table(vblk->sg, vblk->sg_elems);
mutex_init(&vblk->config_lock);
+
INIT_WORK(&vblk->config_work, virtblk_config_changed_work);
vblk->config_enable = true;
@@ -517,7 +745,10 @@
if (err)
goto out_free_vblk;
- vblk->pool = mempool_create_kmalloc_pool(1,sizeof(struct virtblk_req));
+ pool_size = sizeof(struct virtblk_req);
+ if (use_bio)
+ pool_size += sizeof(struct scatterlist) * sg_elems;
+ vblk->pool = mempool_create_kmalloc_pool(1, pool_size);
if (!vblk->pool) {
err = -ENOMEM;
goto out_free_vq;
@@ -530,12 +761,14 @@
goto out_mempool;
}
- q = vblk->disk->queue = blk_init_queue(do_virtblk_request, NULL);
+ q = vblk->disk->queue = blk_init_queue(virtblk_request, NULL);
if (!q) {
err = -ENOMEM;
goto out_put_disk;
}
+ if (use_bio)
+ blk_queue_make_request(q, virtblk_make_request);
q->queuedata = vblk;
virtblk_name_format("vd", index, vblk->disk->disk_name, DISK_NAME_LEN);
@@ -620,7 +853,6 @@
if (!err && opt_io_size)
blk_queue_io_opt(q, blk_size * opt_io_size);
-
add_disk(vblk->disk);
err = device_create_file(disk_to_dev(vblk->disk), &dev_attr_serial);
if (err)
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 060a672..8ab9c3d 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -24,6 +24,8 @@
#include <linux/err.h>
#include <linux/freezer.h>
#include <linux/fs.h>
+#include <linux/splice.h>
+#include <linux/pagemap.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/poll.h>
@@ -474,26 +476,53 @@
return 0;
}
+struct buffer_token {
+ union {
+ void *buf;
+ struct scatterlist *sg;
+ } u;
+ /* If sgpages == 0 then buf is used, else sg is used */
+ unsigned int sgpages;
+};
+
+static void reclaim_sg_pages(struct scatterlist *sg, unsigned int nrpages)
+{
+ int i;
+ struct page *page;
+
+ for (i = 0; i < nrpages; i++) {
+ page = sg_page(&sg[i]);
+ if (!page)
+ break;
+ put_page(page);
+ }
+ kfree(sg);
+}
+
/* Callers must take the port->outvq_lock */
static void reclaim_consumed_buffers(struct port *port)
{
- void *buf;
+ struct buffer_token *tok;
unsigned int len;
if (!port->portdev) {
/* Device has been unplugged. vqs are already gone. */
return;
}
- while ((buf = virtqueue_get_buf(port->out_vq, &len))) {
- kfree(buf);
+ while ((tok = virtqueue_get_buf(port->out_vq, &len))) {
+ if (tok->sgpages)
+ reclaim_sg_pages(tok->u.sg, tok->sgpages);
+ else
+ kfree(tok->u.buf);
+ kfree(tok);
port->outvq_full = false;
}
}
-static ssize_t send_buf(struct port *port, void *in_buf, size_t in_count,
- bool nonblock)
+static ssize_t __send_to_port(struct port *port, struct scatterlist *sg,
+ int nents, size_t in_count,
+ struct buffer_token *tok, bool nonblock)
{
- struct scatterlist sg[1];
struct virtqueue *out_vq;
ssize_t ret;
unsigned long flags;
@@ -505,8 +534,7 @@
reclaim_consumed_buffers(port);
- sg_init_one(sg, in_buf, in_count);
- ret = virtqueue_add_buf(out_vq, sg, 1, 0, in_buf, GFP_ATOMIC);
+ ret = virtqueue_add_buf(out_vq, sg, nents, 0, tok, GFP_ATOMIC);
/* Tell Host to go! */
virtqueue_kick(out_vq);
@@ -544,6 +572,37 @@
return in_count;
}
+static ssize_t send_buf(struct port *port, void *in_buf, size_t in_count,
+ bool nonblock)
+{
+ struct scatterlist sg[1];
+ struct buffer_token *tok;
+
+ tok = kmalloc(sizeof(*tok), GFP_ATOMIC);
+ if (!tok)
+ return -ENOMEM;
+ tok->sgpages = 0;
+ tok->u.buf = in_buf;
+
+ sg_init_one(sg, in_buf, in_count);
+
+ return __send_to_port(port, sg, 1, in_count, tok, nonblock);
+}
+
+static ssize_t send_pages(struct port *port, struct scatterlist *sg, int nents,
+ size_t in_count, bool nonblock)
+{
+ struct buffer_token *tok;
+
+ tok = kmalloc(sizeof(*tok), GFP_ATOMIC);
+ if (!tok)
+ return -ENOMEM;
+ tok->sgpages = nents;
+ tok->u.sg = sg;
+
+ return __send_to_port(port, sg, nents, in_count, tok, nonblock);
+}
+
/*
* Give out the data that's requested from the buffer that we have
* queued up.
@@ -665,6 +724,26 @@
return fill_readbuf(port, ubuf, count, true);
}
+static int wait_port_writable(struct port *port, bool nonblock)
+{
+ int ret;
+
+ if (will_write_block(port)) {
+ if (nonblock)
+ return -EAGAIN;
+
+ ret = wait_event_freezable(port->waitqueue,
+ !will_write_block(port));
+ if (ret < 0)
+ return ret;
+ }
+ /* Port got hot-unplugged. */
+ if (!port->guest_connected)
+ return -ENODEV;
+
+ return 0;
+}
+
static ssize_t port_fops_write(struct file *filp, const char __user *ubuf,
size_t count, loff_t *offp)
{
@@ -681,18 +760,9 @@
nonblock = filp->f_flags & O_NONBLOCK;
- if (will_write_block(port)) {
- if (nonblock)
- return -EAGAIN;
-
- ret = wait_event_freezable(port->waitqueue,
- !will_write_block(port));
- if (ret < 0)
- return ret;
- }
- /* Port got hot-unplugged. */
- if (!port->guest_connected)
- return -ENODEV;
+ ret = wait_port_writable(port, nonblock);
+ if (ret < 0)
+ return ret;
count = min((size_t)(32 * 1024), count);
@@ -725,6 +795,93 @@
return ret;
}
+struct sg_list {
+ unsigned int n;
+ unsigned int size;
+ size_t len;
+ struct scatterlist *sg;
+};
+
+static int pipe_to_sg(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
+ struct splice_desc *sd)
+{
+ struct sg_list *sgl = sd->u.data;
+ unsigned int offset, len;
+
+ if (sgl->n == sgl->size)
+ return 0;
+
+ /* Try lock this page */
+ if (buf->ops->steal(pipe, buf) == 0) {
+ /* Get reference and unlock page for moving */
+ get_page(buf->page);
+ unlock_page(buf->page);
+
+ len = min(buf->len, sd->len);
+ sg_set_page(&(sgl->sg[sgl->n]), buf->page, len, buf->offset);
+ } else {
+ /* Failback to copying a page */
+ struct page *page = alloc_page(GFP_KERNEL);
+ char *src = buf->ops->map(pipe, buf, 1);
+ char *dst;
+
+ if (!page)
+ return -ENOMEM;
+ dst = kmap(page);
+
+ offset = sd->pos & ~PAGE_MASK;
+
+ len = sd->len;
+ if (len + offset > PAGE_SIZE)
+ len = PAGE_SIZE - offset;
+
+ memcpy(dst + offset, src + buf->offset, len);
+
+ kunmap(page);
+ buf->ops->unmap(pipe, buf, src);
+
+ sg_set_page(&(sgl->sg[sgl->n]), page, len, offset);
+ }
+ sgl->n++;
+ sgl->len += len;
+
+ return len;
+}
+
+/* Faster zero-copy write by splicing */
+static ssize_t port_fops_splice_write(struct pipe_inode_info *pipe,
+ struct file *filp, loff_t *ppos,
+ size_t len, unsigned int flags)
+{
+ struct port *port = filp->private_data;
+ struct sg_list sgl;
+ ssize_t ret;
+ struct splice_desc sd = {
+ .total_len = len,
+ .flags = flags,
+ .pos = *ppos,
+ .u.data = &sgl,
+ };
+
+ ret = wait_port_writable(port, filp->f_flags & O_NONBLOCK);
+ if (ret < 0)
+ return ret;
+
+ sgl.n = 0;
+ sgl.len = 0;
+ sgl.size = pipe->nrbufs;
+ sgl.sg = kmalloc(sizeof(struct scatterlist) * sgl.size, GFP_KERNEL);
+ if (unlikely(!sgl.sg))
+ return -ENOMEM;
+
+ sg_init_table(sgl.sg, sgl.size);
+ ret = __splice_from_pipe(pipe, &sd, pipe_to_sg);
+ if (likely(ret > 0))
+ ret = send_pages(port, sgl.sg, sgl.n, sgl.len, true);
+
+ return ret;
+}
+
static unsigned int port_fops_poll(struct file *filp, poll_table *wait)
{
struct port *port;
@@ -856,6 +1013,7 @@
.open = port_fops_open,
.read = port_fops_read,
.write = port_fops_write,
+ .splice_write = port_fops_splice_write,
.poll = port_fops_poll,
.release = port_fops_release,
.fasync = port_fops_fasync,
diff --git a/drivers/lguest/lguest_device.c b/drivers/lguest/lguest_device.c
index 9e8388e..fc92ccb 100644
--- a/drivers/lguest/lguest_device.c
+++ b/drivers/lguest/lguest_device.c
@@ -263,6 +263,9 @@
struct virtqueue *vq;
int err;
+ if (!name)
+ return NULL;
+
/* We must have this many virtqueues. */
if (index >= ldev->desc->num_vq)
return ERR_PTR(-ENOENT);
@@ -296,7 +299,7 @@
* to 'true': the host just a(nother) SMP CPU, so we only need inter-cpu
* barriers.
*/
- vq = vring_new_virtqueue(lvq->config.num, LGUEST_VRING_ALIGN, vdev,
+ vq = vring_new_virtqueue(index, lvq->config.num, LGUEST_VRING_ALIGN, vdev,
true, lvq->pages, lg_notify, callback, name);
if (!vq) {
err = -ENOMEM;
diff --git a/drivers/remoteproc/remoteproc_virtio.c b/drivers/remoteproc/remoteproc_virtio.c
index 3541b44..e7a4780 100644
--- a/drivers/remoteproc/remoteproc_virtio.c
+++ b/drivers/remoteproc/remoteproc_virtio.c
@@ -84,6 +84,9 @@
if (id >= ARRAY_SIZE(rvdev->vring))
return ERR_PTR(-EINVAL);
+ if (!name)
+ return NULL;
+
ret = rproc_alloc_vring(rvdev, id);
if (ret)
return ERR_PTR(ret);
@@ -103,7 +106,7 @@
* Create the new vq, and tell virtio we're not interested in
* the 'weak' smp barriers, since we're talking with a real device.
*/
- vq = vring_new_virtqueue(len, rvring->align, vdev, false, addr,
+ vq = vring_new_virtqueue(id, len, rvring->align, vdev, false, addr,
rproc_virtio_notify, callback, name);
if (!vq) {
dev_err(dev, "vring_new_virtqueue %s failed\n", name);
diff --git a/drivers/rpmsg/Kconfig b/drivers/rpmsg/Kconfig
index 32aead6..2bd911f 100644
--- a/drivers/rpmsg/Kconfig
+++ b/drivers/rpmsg/Kconfig
@@ -4,7 +4,6 @@
config RPMSG
tristate
select VIRTIO
- select VIRTIO_RING
depends on EXPERIMENTAL
endmenu
diff --git a/drivers/s390/kvm/kvm_virtio.c b/drivers/s390/kvm/kvm_virtio.c
index 47cccd5..7dabef6 100644
--- a/drivers/s390/kvm/kvm_virtio.c
+++ b/drivers/s390/kvm/kvm_virtio.c
@@ -190,6 +190,9 @@
if (index >= kdev->desc->num_vq)
return ERR_PTR(-ENOENT);
+ if (!name)
+ return NULL;
+
config = kvm_vq_config(kdev->desc)+index;
err = vmem_add_mapping(config->address,
@@ -198,7 +201,7 @@
if (err)
goto out;
- vq = vring_new_virtqueue(config->num, KVM_S390_VIRTIO_RING_ALIGN,
+ vq = vring_new_virtqueue(index, config->num, KVM_S390_VIRTIO_RING_ALIGN,
vdev, true, (void *) config->address,
kvm_notify, callback, name);
if (!vq) {
diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
index f38b17a..8d5bddb 100644
--- a/drivers/virtio/Kconfig
+++ b/drivers/virtio/Kconfig
@@ -1,11 +1,9 @@
-# Virtio always gets selected by whoever wants it.
config VIRTIO
tristate
-
-# Similarly the virtio ring implementation.
-config VIRTIO_RING
- tristate
- depends on VIRTIO
+ ---help---
+ This option is selected by any driver which implements the virtio
+ bus, such as CONFIG_VIRTIO_PCI, CONFIG_VIRTIO_MMIO, CONFIG_LGUEST,
+ CONFIG_RPMSG or CONFIG_S390_GUEST.
menu "Virtio drivers"
@@ -13,7 +11,6 @@
tristate "PCI driver for virtio devices (EXPERIMENTAL)"
depends on PCI && EXPERIMENTAL
select VIRTIO
- select VIRTIO_RING
---help---
This drivers provides support for virtio based paravirtual device
drivers over PCI. This requires that your VMM has appropriate PCI
@@ -26,9 +23,8 @@
If unsure, say M.
config VIRTIO_BALLOON
- tristate "Virtio balloon driver (EXPERIMENTAL)"
- select VIRTIO
- select VIRTIO_RING
+ tristate "Virtio balloon driver"
+ depends on VIRTIO
---help---
This driver supports increasing and decreasing the amount
of memory within a KVM guest.
@@ -39,7 +35,6 @@
tristate "Platform bus driver for memory mapped virtio devices (EXPERIMENTAL)"
depends on HAS_IOMEM && EXPERIMENTAL
select VIRTIO
- select VIRTIO_RING
---help---
This drivers provides support for memory mapped virtio
platform device driver.
diff --git a/drivers/virtio/Makefile b/drivers/virtio/Makefile
index 5a4c63c..9076635 100644
--- a/drivers/virtio/Makefile
+++ b/drivers/virtio/Makefile
@@ -1,5 +1,4 @@
-obj-$(CONFIG_VIRTIO) += virtio.o
-obj-$(CONFIG_VIRTIO_RING) += virtio_ring.o
+obj-$(CONFIG_VIRTIO) += virtio.o virtio_ring.o
obj-$(CONFIG_VIRTIO_MMIO) += virtio_mmio.o
obj-$(CONFIG_VIRTIO_PCI) += virtio_pci.o
obj-$(CONFIG_VIRTIO_BALLOON) += virtio_balloon.o
diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
index c3b3f7f..1e8659c 100644
--- a/drivers/virtio/virtio.c
+++ b/drivers/virtio/virtio.c
@@ -159,7 +159,7 @@
drv->remove(dev);
/* Driver should have reset device. */
- BUG_ON(dev->config->get_status(dev));
+ WARN_ON_ONCE(dev->config->get_status(dev));
/* Acknowledge the device's existence again. */
add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
index 453db0c..6b1b7e1 100644
--- a/drivers/virtio/virtio_mmio.c
+++ b/drivers/virtio/virtio_mmio.c
@@ -131,9 +131,6 @@
/* the number of entries in the queue */
unsigned int num;
- /* the index of the queue */
- int queue_index;
-
/* the virtual address of the ring queue */
void *queue;
@@ -225,11 +222,10 @@
static void vm_notify(struct virtqueue *vq)
{
struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vq->vdev);
- struct virtio_mmio_vq_info *info = vq->priv;
/* We write the queue's selector into the notification register to
* signal the other end */
- writel(info->queue_index, vm_dev->base + VIRTIO_MMIO_QUEUE_NOTIFY);
+ writel(virtqueue_get_queue_index(vq), vm_dev->base + VIRTIO_MMIO_QUEUE_NOTIFY);
}
/* Notify all virtqueues on an interrupt. */
@@ -270,6 +266,7 @@
struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vq->vdev);
struct virtio_mmio_vq_info *info = vq->priv;
unsigned long flags, size;
+ unsigned int index = virtqueue_get_queue_index(vq);
spin_lock_irqsave(&vm_dev->lock, flags);
list_del(&info->node);
@@ -278,7 +275,7 @@
vring_del_virtqueue(vq);
/* Select and deactivate the queue */
- writel(info->queue_index, vm_dev->base + VIRTIO_MMIO_QUEUE_SEL);
+ writel(index, vm_dev->base + VIRTIO_MMIO_QUEUE_SEL);
writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
size = PAGE_ALIGN(vring_size(info->num, VIRTIO_MMIO_VRING_ALIGN));
@@ -309,6 +306,9 @@
unsigned long flags, size;
int err;
+ if (!name)
+ return NULL;
+
/* Select the queue we're interested in */
writel(index, vm_dev->base + VIRTIO_MMIO_QUEUE_SEL);
@@ -324,7 +324,6 @@
err = -ENOMEM;
goto error_kmalloc;
}
- info->queue_index = index;
/* Allocate pages for the queue - start with a queue as big as
* possible (limited by maximum size allowed by device), drop down
@@ -332,11 +331,21 @@
* and two rings (which makes it "alignment_size * 2")
*/
info->num = readl(vm_dev->base + VIRTIO_MMIO_QUEUE_NUM_MAX);
+
+ /* If the device reports a 0 entry queue, we won't be able to
+ * use it to perform I/O, and vring_new_virtqueue() can't create
+ * empty queues anyway, so don't bother to set up the device.
+ */
+ if (info->num == 0) {
+ err = -ENOENT;
+ goto error_alloc_pages;
+ }
+
while (1) {
size = PAGE_ALIGN(vring_size(info->num,
VIRTIO_MMIO_VRING_ALIGN));
- /* Already smallest possible allocation? */
- if (size <= VIRTIO_MMIO_VRING_ALIGN * 2) {
+ /* Did the last iter shrink the queue below minimum size? */
+ if (size < VIRTIO_MMIO_VRING_ALIGN * 2) {
err = -ENOMEM;
goto error_alloc_pages;
}
@@ -356,7 +365,7 @@
vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
/* Create the vring */
- vq = vring_new_virtqueue(info->num, VIRTIO_MMIO_VRING_ALIGN, vdev,
+ vq = vring_new_virtqueue(index, info->num, VIRTIO_MMIO_VRING_ALIGN, vdev,
true, info->queue, vm_notify, callback, name);
if (!vq) {
err = -ENOMEM;
diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index 2e03d41..c33aea3 100644
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -48,6 +48,7 @@
int msix_enabled;
int intx_enabled;
struct msix_entry *msix_entries;
+ cpumask_var_t *msix_affinity_masks;
/* Name strings for interrupts. This size should be enough,
* and I'm too lazy to allocate each name separately. */
char (*msix_names)[256];
@@ -79,9 +80,6 @@
/* the number of entries in the queue */
int num;
- /* the index of the queue */
- int queue_index;
-
/* the virtual address of the ring queue */
void *queue;
@@ -202,11 +200,11 @@
static void vp_notify(struct virtqueue *vq)
{
struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
- struct virtio_pci_vq_info *info = vq->priv;
/* we write the queue's selector into the notification register to
* signal the other end */
- iowrite16(info->queue_index, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_NOTIFY);
+ iowrite16(virtqueue_get_queue_index(vq),
+ vp_dev->ioaddr + VIRTIO_PCI_QUEUE_NOTIFY);
}
/* Handle a configuration change: Tell driver if it wants to know. */
@@ -279,6 +277,10 @@
for (i = 0; i < vp_dev->msix_used_vectors; ++i)
free_irq(vp_dev->msix_entries[i].vector, vp_dev);
+ for (i = 0; i < vp_dev->msix_vectors; i++)
+ if (vp_dev->msix_affinity_masks[i])
+ free_cpumask_var(vp_dev->msix_affinity_masks[i]);
+
if (vp_dev->msix_enabled) {
/* Disable the vector used for configuration */
iowrite16(VIRTIO_MSI_NO_VECTOR,
@@ -296,6 +298,8 @@
vp_dev->msix_names = NULL;
kfree(vp_dev->msix_entries);
vp_dev->msix_entries = NULL;
+ kfree(vp_dev->msix_affinity_masks);
+ vp_dev->msix_affinity_masks = NULL;
}
static int vp_request_msix_vectors(struct virtio_device *vdev, int nvectors,
@@ -314,6 +318,15 @@
GFP_KERNEL);
if (!vp_dev->msix_names)
goto error;
+ vp_dev->msix_affinity_masks
+ = kzalloc(nvectors * sizeof *vp_dev->msix_affinity_masks,
+ GFP_KERNEL);
+ if (!vp_dev->msix_affinity_masks)
+ goto error;
+ for (i = 0; i < nvectors; ++i)
+ if (!alloc_cpumask_var(&vp_dev->msix_affinity_masks[i],
+ GFP_KERNEL))
+ goto error;
for (i = 0; i < nvectors; ++i)
vp_dev->msix_entries[i].entry = i;
@@ -402,7 +415,6 @@
if (!info)
return ERR_PTR(-ENOMEM);
- info->queue_index = index;
info->num = num;
info->msix_vector = msix_vec;
@@ -418,7 +430,7 @@
vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
/* create the vring */
- vq = vring_new_virtqueue(info->num, VIRTIO_PCI_VRING_ALIGN, vdev,
+ vq = vring_new_virtqueue(index, info->num, VIRTIO_PCI_VRING_ALIGN, vdev,
true, info->queue, vp_notify, callback, name);
if (!vq) {
err = -ENOMEM;
@@ -467,7 +479,8 @@
list_del(&info->node);
spin_unlock_irqrestore(&vp_dev->lock, flags);
- iowrite16(info->queue_index, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_SEL);
+ iowrite16(virtqueue_get_queue_index(vq),
+ vp_dev->ioaddr + VIRTIO_PCI_QUEUE_SEL);
if (vp_dev->msix_enabled) {
iowrite16(VIRTIO_MSI_NO_VECTOR,
@@ -542,7 +555,10 @@
vp_dev->per_vq_vectors = per_vq_vectors;
allocated_vectors = vp_dev->msix_used_vectors;
for (i = 0; i < nvqs; ++i) {
- if (!callbacks[i] || !vp_dev->msix_enabled)
+ if (!names[i]) {
+ vqs[i] = NULL;
+ continue;
+ } else if (!callbacks[i] || !vp_dev->msix_enabled)
msix_vec = VIRTIO_MSI_NO_VECTOR;
else if (vp_dev->per_vq_vectors)
msix_vec = allocated_vectors++;
@@ -609,6 +625,35 @@
return pci_name(vp_dev->pci_dev);
}
+/* Setup the affinity for a virtqueue:
+ * - force the affinity for per vq vector
+ * - OR over all affinities for shared MSI
+ * - ignore the affinity request if we're using INTX
+ */
+static int vp_set_vq_affinity(struct virtqueue *vq, int cpu)
+{
+ struct virtio_device *vdev = vq->vdev;
+ struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+ struct virtio_pci_vq_info *info = vq->priv;
+ struct cpumask *mask;
+ unsigned int irq;
+
+ if (!vq->callback)
+ return -EINVAL;
+
+ if (vp_dev->msix_enabled) {
+ mask = vp_dev->msix_affinity_masks[info->msix_vector];
+ irq = vp_dev->msix_entries[info->msix_vector].vector;
+ if (cpu == -1)
+ irq_set_affinity_hint(irq, NULL);
+ else {
+ cpumask_set_cpu(cpu, mask);
+ irq_set_affinity_hint(irq, mask);
+ }
+ }
+ return 0;
+}
+
static struct virtio_config_ops virtio_pci_config_ops = {
.get = vp_get,
.set = vp_set,
@@ -620,6 +665,7 @@
.get_features = vp_get_features,
.finalize_features = vp_finalize_features,
.bus_name = vp_bus_name,
+ .set_vq_affinity = vp_set_vq_affinity,
};
static void virtio_pci_release_dev(struct device *_d)
@@ -673,8 +719,10 @@
goto out_enable_device;
vp_dev->ioaddr = pci_iomap(pci_dev, 0, 0);
- if (vp_dev->ioaddr == NULL)
+ if (vp_dev->ioaddr == NULL) {
+ err = -ENOMEM;
goto out_req_regions;
+ }
pci_set_drvdata(pci_dev, vp_dev);
pci_set_master(pci_dev);
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 5aa43c3..e639584 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -106,6 +106,9 @@
/* How to notify other side. FIXME: commonalize hcalls! */
void (*notify)(struct virtqueue *vq);
+ /* Index of the queue */
+ int queue_index;
+
#ifdef DEBUG
/* They're supposed to lock for us. */
unsigned int in_use;
@@ -171,6 +174,13 @@
return head;
}
+int virtqueue_get_queue_index(struct virtqueue *_vq)
+{
+ struct vring_virtqueue *vq = to_vvq(_vq);
+ return vq->queue_index;
+}
+EXPORT_SYMBOL_GPL(virtqueue_get_queue_index);
+
/**
* virtqueue_add_buf - expose buffer to other end
* @vq: the struct virtqueue we're talking about.
@@ -616,7 +626,8 @@
}
EXPORT_SYMBOL_GPL(vring_interrupt);
-struct virtqueue *vring_new_virtqueue(unsigned int num,
+struct virtqueue *vring_new_virtqueue(unsigned int index,
+ unsigned int num,
unsigned int vring_align,
struct virtio_device *vdev,
bool weak_barriers,
@@ -647,6 +658,7 @@
vq->broken = false;
vq->last_used_idx = 0;
vq->num_added = 0;
+ vq->queue_index = index;
list_add_tail(&vq->vq.list, &vdev->vqs);
#ifdef DEBUG
vq->in_use = false;
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index a1ba8bb..533b115 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -50,6 +50,8 @@
unsigned int virtqueue_get_vring_size(struct virtqueue *vq);
+int virtqueue_get_queue_index(struct virtqueue *vq);
+
/**
* virtio_device - representation of a device using virtio
* @index: unique position on the virtio bus
diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
index fc457f4..e2850a7 100644
--- a/include/linux/virtio_config.h
+++ b/include/linux/virtio_config.h
@@ -84,7 +84,9 @@
* nvqs: the number of virtqueues to find
* vqs: on success, includes new virtqueues
* callbacks: array of callbacks, for each virtqueue
+ * include a NULL entry for vqs that do not need a callback
* names: array of virtqueue names (mainly for debugging)
+ * include a NULL entry for vqs unused by driver
* Returns 0 on success or error status
* @del_vqs: free virtqueues found by find_vqs().
* @get_features: get the array of feature bits for this device.
@@ -98,6 +100,7 @@
* vdev: the virtio_device
* This returns a pointer to the bus name a la pci_name from which
* the caller can then copy.
+ * @set_vq_affinity: set the affinity for a virtqueue.
*/
typedef void vq_callback_t(struct virtqueue *);
struct virtio_config_ops {
@@ -116,6 +119,7 @@
u32 (*get_features)(struct virtio_device *vdev);
void (*finalize_features)(struct virtio_device *vdev);
const char *(*bus_name)(struct virtio_device *vdev);
+ int (*set_vq_affinity)(struct virtqueue *vq, int cpu);
};
/* If driver didn't advertise the feature, it will never appear. */
@@ -190,5 +194,24 @@
return vdev->config->bus_name(vdev);
}
+/**
+ * virtqueue_set_affinity - setting affinity for a virtqueue
+ * @vq: the virtqueue
+ * @cpu: the cpu no.
+ *
+ * Pay attention the function are best-effort: the affinity hint may not be set
+ * due to config support, irq type and sharing.
+ *
+ */
+static inline
+int virtqueue_set_affinity(struct virtqueue *vq, int cpu)
+{
+ struct virtio_device *vdev = vq->vdev;
+ if (vdev->config->set_vq_affinity)
+ return vdev->config->set_vq_affinity(vq, cpu);
+ return 0;
+}
+
+
#endif /* __KERNEL__ */
#endif /* _LINUX_VIRTIO_CONFIG_H */
diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h
index e338730..c2d793a 100644
--- a/include/linux/virtio_ring.h
+++ b/include/linux/virtio_ring.h
@@ -165,7 +165,8 @@
struct virtio_device;
struct virtqueue;
-struct virtqueue *vring_new_virtqueue(unsigned int num,
+struct virtqueue *vring_new_virtqueue(unsigned int index,
+ unsigned int num,
unsigned int vring_align,
struct virtio_device *vdev,
bool weak_barriers,
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index cdcb594..31e4f55 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4200,12 +4200,6 @@
buf->private = 0;
}
-static int buffer_pipe_buf_steal(struct pipe_inode_info *pipe,
- struct pipe_buffer *buf)
-{
- return 1;
-}
-
static void buffer_pipe_buf_get(struct pipe_inode_info *pipe,
struct pipe_buffer *buf)
{
@@ -4221,7 +4215,7 @@
.unmap = generic_pipe_buf_unmap,
.confirm = generic_pipe_buf_confirm,
.release = buffer_pipe_buf_release,
- .steal = buffer_pipe_buf_steal,
+ .steal = generic_pipe_buf_steal,
.get = buffer_pipe_buf_get,
};
diff --git a/tools/lguest/lguest.c b/tools/lguest/lguest.c
index f759f4f..fd2f922 100644
--- a/tools/lguest/lguest.c
+++ b/tools/lguest/lguest.c
@@ -1299,6 +1299,7 @@
dev->feature_len = 0;
dev->num_vq = 0;
dev->running = false;
+ dev->next = NULL;
/*
* Append to device list. Prepending to a single-linked list is
diff --git a/tools/virtio/virtio-trace/Makefile b/tools/virtio/virtio-trace/Makefile
new file mode 100644
index 0000000..0d23816
--- /dev/null
+++ b/tools/virtio/virtio-trace/Makefile
@@ -0,0 +1,13 @@
+CC = gcc
+CFLAGS = -O2 -Wall -pthread
+
+all: trace-agent
+
+.c.o:
+ $(CC) $(CFLAGS) -c $^ -o $@
+
+trace-agent: trace-agent.o trace-agent-ctl.o trace-agent-rw.o
+ $(CC) $(CFLAGS) -o $@ $^
+
+clean:
+ rm -f *.o trace-agent
diff --git a/tools/virtio/virtio-trace/README b/tools/virtio/virtio-trace/README
new file mode 100644
index 0000000..b64845b
--- /dev/null
+++ b/tools/virtio/virtio-trace/README
@@ -0,0 +1,118 @@
+Trace Agent for virtio-trace
+============================
+
+Trace agent is a user tool for sending trace data of a guest to a Host in low
+overhead. Trace agent has the following functions:
+ - splice a page of ring-buffer to read_pipe without memory copying
+ - splice the page from write_pipe to virtio-console without memory copying
+ - write trace data to stdout by using -o option
+ - controlled by start/stop orders from a Host
+
+The trace agent operates as follows:
+ 1) Initialize all structures.
+ 2) Create a read/write thread per CPU. Each thread is bound to a CPU.
+ The read/write threads hold it.
+ 3) A controller thread does poll() for a start order of a host.
+ 4) After the controller of the trace agent receives a start order from a host,
+ the controller wake read/write threads.
+ 5) The read/write threads start to read trace data from ring-buffers and
+ write the data to virtio-serial.
+ 6) If the controller receives a stop order from a host, the read/write threads
+ stop to read trace data.
+
+
+Files
+=====
+
+README: this file
+Makefile: Makefile of trace agent for virtio-trace
+trace-agent.c: includes main function, sets up for operating trace agent
+trace-agent.h: includes all structures and some macros
+trace-agent-ctl.c: includes controller function for read/write threads
+trace-agent-rw.c: includes read/write threads function
+
+
+Setup
+=====
+
+To use this trace agent for virtio-trace, we need to prepare some virtio-serial
+I/Fs.
+
+1) Make FIFO in a host
+ virtio-trace uses virtio-serial pipe as trace data paths as to the number
+of CPUs and a control path, so FIFO (named pipe) should be created as follows:
+ # mkdir /tmp/virtio-trace/
+ # mkfifo /tmp/virtio-trace/trace-path-cpu{0,1,2,...,X}.{in,out}
+ # mkfifo /tmp/virtio-trace/agent-ctl-path.{in,out}
+
+For example, if a guest use three CPUs, the names are
+ trace-path-cpu{0,1,2}.{in.out}
+and
+ agent-ctl-path.{in,out}.
+
+2) Set up of virtio-serial pipe in a host
+ Add qemu option to use virtio-serial pipe.
+
+ ##virtio-serial device##
+ -device virtio-serial-pci,id=virtio-serial0\
+ ##control path##
+ -chardev pipe,id=charchannel0,path=/tmp/virtio-trace/agent-ctl-path\
+ -device virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,\
+ id=channel0,name=agent-ctl-path\
+ ##data path##
+ -chardev pipe,id=charchannel1,path=/tmp/virtio-trace/trace-path-cpu0\
+ -device virtserialport,bus=virtio-serial0.0,nr=2,chardev=charchannel0,\
+ id=channel1,name=trace-path-cpu0\
+ ...
+
+If you manage guests with libvirt, add the following tags to domain XML files.
+Then, libvirt passes the same command option to qemu.
+
+ <channel type='pipe'>
+ <source path='/tmp/virtio-trace/agent-ctl-path'/>
+ <target type='virtio' name='agent-ctl-path'/>
+ <address type='virtio-serial' controller='0' bus='0' port='0'/>
+ </channel>
+ <channel type='pipe'>
+ <source path='/tmp/virtio-trace/trace-path-cpu0'/>
+ <target type='virtio' name='trace-path-cpu0'/>
+ <address type='virtio-serial' controller='0' bus='0' port='1'/>
+ </channel>
+ ...
+Here, chardev names are restricted to trace-path-cpuX and agent-ctl-path. For
+example, if a guest use three CPUs, chardev names should be trace-path-cpu0,
+trace-path-cpu1, trace-path-cpu2, and agent-ctl-path.
+
+3) Boot the guest
+ You can find some chardev in /dev/virtio-ports/ in the guest.
+
+
+Run
+===
+
+0) Build trace agent in a guest
+ $ make
+
+1) Enable ftrace in the guest
+ <Example>
+ # echo 1 > /sys/kernel/debug/tracing/events/sched/enable
+
+2) Run trace agent in the guest
+ This agent must be operated as root.
+ # ./trace-agent
+read/write threads in the agent wait for start order from host. If you add -o
+option, trace data are output via stdout in the guest.
+
+3) Open FIFO in a host
+ # cat /tmp/virtio-trace/trace-path-cpu0.out
+If a host does not open these, trace data get stuck in buffers of virtio. Then,
+the guest will stop by specification of chardev in QEMU. This blocking mode may
+be solved in the future.
+
+4) Start to read trace data by ordering from a host
+ A host injects read start order to the guest via virtio-serial.
+ # echo 1 > /tmp/virtio-trace/agent-ctl-path.in
+
+5) Stop to read trace data by ordering from a host
+ A host injects read stop order to the guest via virtio-serial.
+ # echo 0 > /tmp/virtio-trace/agent-ctl-path.in
diff --git a/tools/virtio/virtio-trace/trace-agent-ctl.c b/tools/virtio/virtio-trace/trace-agent-ctl.c
new file mode 100644
index 0000000..a2d0403
--- /dev/null
+++ b/tools/virtio/virtio-trace/trace-agent-ctl.c
@@ -0,0 +1,137 @@
+/*
+ * Controller of read/write threads for virtio-trace
+ *
+ * Copyright (C) 2012 Hitachi, Ltd.
+ * Created by Yoshihiro Yunomae <yoshihiro.yunomae.ez@hitachi.com>
+ * Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
+ *
+ * Licensed under GPL version 2 only.
+ *
+ */
+
+#define _GNU_SOURCE
+#include <fcntl.h>
+#include <poll.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include "trace-agent.h"
+
+#define HOST_MSG_SIZE 256
+#define EVENT_WAIT_MSEC 100
+
+static volatile sig_atomic_t global_signal_val;
+bool global_sig_receive; /* default false */
+bool global_run_operation; /* default false*/
+
+/* Handle SIGTERM/SIGINT/SIGQUIT to exit */
+static void signal_handler(int sig)
+{
+ global_signal_val = sig;
+}
+
+int rw_ctl_init(const char *ctl_path)
+{
+ int ctl_fd;
+
+ ctl_fd = open(ctl_path, O_RDONLY);
+ if (ctl_fd == -1) {
+ pr_err("Cannot open ctl_fd\n");
+ goto error;
+ }
+
+ return ctl_fd;
+
+error:
+ exit(EXIT_FAILURE);
+}
+
+static int wait_order(int ctl_fd)
+{
+ struct pollfd poll_fd;
+ int ret = 0;
+
+ while (!global_sig_receive) {
+ poll_fd.fd = ctl_fd;
+ poll_fd.events = POLLIN;
+
+ ret = poll(&poll_fd, 1, EVENT_WAIT_MSEC);
+
+ if (global_signal_val) {
+ global_sig_receive = true;
+ pr_info("Receive interrupt %d\n", global_signal_val);
+
+ /* Wakes rw-threads when they are sleeping */
+ if (!global_run_operation)
+ pthread_cond_broadcast(&cond_wakeup);
+
+ ret = -1;
+ break;
+ }
+
+ if (ret < 0) {
+ pr_err("Polling error\n");
+ goto error;
+ }
+
+ if (ret)
+ break;
+ };
+
+ return ret;
+
+error:
+ exit(EXIT_FAILURE);
+}
+
+/*
+ * contol read/write threads by handling global_run_operation
+ */
+void *rw_ctl_loop(int ctl_fd)
+{
+ ssize_t rlen;
+ char buf[HOST_MSG_SIZE];
+ int ret;
+
+ /* Setup signal handlers */
+ signal(SIGTERM, signal_handler);
+ signal(SIGINT, signal_handler);
+ signal(SIGQUIT, signal_handler);
+
+ while (!global_sig_receive) {
+
+ ret = wait_order(ctl_fd);
+ if (ret < 0)
+ break;
+
+ rlen = read(ctl_fd, buf, sizeof(buf));
+ if (rlen < 0) {
+ pr_err("read data error in ctl thread\n");
+ goto error;
+ }
+
+ if (rlen == 2 && buf[0] == '1') {
+ /*
+ * If host writes '1' to a control path,
+ * this controller wakes all read/write threads.
+ */
+ global_run_operation = true;
+ pthread_cond_broadcast(&cond_wakeup);
+ pr_debug("Wake up all read/write threads\n");
+ } else if (rlen == 2 && buf[0] == '0') {
+ /*
+ * If host writes '0' to a control path, read/write
+ * threads will wait for notification from Host.
+ */
+ global_run_operation = false;
+ pr_debug("Stop all read/write threads\n");
+ } else
+ pr_info("Invalid host notification: %s\n", buf);
+ }
+
+ return NULL;
+
+error:
+ exit(EXIT_FAILURE);
+}
diff --git a/tools/virtio/virtio-trace/trace-agent-rw.c b/tools/virtio/virtio-trace/trace-agent-rw.c
new file mode 100644
index 0000000..3aace5e
--- /dev/null
+++ b/tools/virtio/virtio-trace/trace-agent-rw.c
@@ -0,0 +1,192 @@
+/*
+ * Read/write thread of a guest agent for virtio-trace
+ *
+ * Copyright (C) 2012 Hitachi, Ltd.
+ * Created by Yoshihiro Yunomae <yoshihiro.yunomae.ez@hitachi.com>
+ * Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
+ *
+ * Licensed under GPL version 2 only.
+ *
+ */
+
+#define _GNU_SOURCE
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/syscall.h>
+#include "trace-agent.h"
+
+#define READ_WAIT_USEC 100000
+
+void *rw_thread_info_new(void)
+{
+ struct rw_thread_info *rw_ti;
+
+ rw_ti = zalloc(sizeof(struct rw_thread_info));
+ if (rw_ti == NULL) {
+ pr_err("rw_thread_info zalloc error\n");
+ exit(EXIT_FAILURE);
+ }
+
+ rw_ti->cpu_num = -1;
+ rw_ti->in_fd = -1;
+ rw_ti->out_fd = -1;
+ rw_ti->read_pipe = -1;
+ rw_ti->write_pipe = -1;
+ rw_ti->pipe_size = PIPE_INIT;
+
+ return rw_ti;
+}
+
+void *rw_thread_init(int cpu, const char *in_path, const char *out_path,
+ bool stdout_flag, unsigned long pipe_size,
+ struct rw_thread_info *rw_ti)
+{
+ int data_pipe[2];
+
+ rw_ti->cpu_num = cpu;
+
+ /* set read(input) fd */
+ rw_ti->in_fd = open(in_path, O_RDONLY);
+ if (rw_ti->in_fd == -1) {
+ pr_err("Could not open in_fd (CPU:%d)\n", cpu);
+ goto error;
+ }
+
+ /* set write(output) fd */
+ if (!stdout_flag) {
+ /* virtio-serial output mode */
+ rw_ti->out_fd = open(out_path, O_WRONLY);
+ if (rw_ti->out_fd == -1) {
+ pr_err("Could not open out_fd (CPU:%d)\n", cpu);
+ goto error;
+ }
+ } else
+ /* stdout mode */
+ rw_ti->out_fd = STDOUT_FILENO;
+
+ if (pipe2(data_pipe, O_NONBLOCK) < 0) {
+ pr_err("Could not create pipe in rw-thread(%d)\n", cpu);
+ goto error;
+ }
+
+ /*
+ * Size of pipe is 64kB in default based on fs/pipe.c.
+ * To read/write trace data speedy, pipe size is changed.
+ */
+ if (fcntl(*data_pipe, F_SETPIPE_SZ, pipe_size) < 0) {
+ pr_err("Could not change pipe size in rw-thread(%d)\n", cpu);
+ goto error;
+ }
+
+ rw_ti->read_pipe = data_pipe[1];
+ rw_ti->write_pipe = data_pipe[0];
+ rw_ti->pipe_size = pipe_size;
+
+ return NULL;
+
+error:
+ exit(EXIT_FAILURE);
+}
+
+/* Bind a thread to a cpu */
+static void bind_cpu(int cpu_num)
+{
+ cpu_set_t mask;
+
+ CPU_ZERO(&mask);
+ CPU_SET(cpu_num, &mask);
+
+ /* bind my thread to cpu_num by assigning zero to the first argument */
+ if (sched_setaffinity(0, sizeof(mask), &mask) == -1)
+ pr_err("Could not set CPU#%d affinity\n", (int)cpu_num);
+}
+
+static void *rw_thread_main(void *thread_info)
+{
+ ssize_t rlen, wlen;
+ ssize_t ret;
+ struct rw_thread_info *ts = (struct rw_thread_info *)thread_info;
+
+ bind_cpu(ts->cpu_num);
+
+ while (1) {
+ /* Wait for a read order of trace data by Host OS */
+ if (!global_run_operation) {
+ pthread_mutex_lock(&mutex_notify);
+ pthread_cond_wait(&cond_wakeup, &mutex_notify);
+ pthread_mutex_unlock(&mutex_notify);
+ }
+
+ if (global_sig_receive)
+ break;
+
+ /*
+ * Each thread read trace_pipe_raw of each cpu bounding the
+ * thread, so contention of multi-threads does not occur.
+ */
+ rlen = splice(ts->in_fd, NULL, ts->read_pipe, NULL,
+ ts->pipe_size, SPLICE_F_MOVE | SPLICE_F_MORE);
+
+ if (rlen < 0) {
+ pr_err("Splice_read in rw-thread(%d)\n", ts->cpu_num);
+ goto error;
+ } else if (rlen == 0) {
+ /*
+ * If trace data do not exist or are unreadable not
+ * for exceeding the page size, splice_read returns
+ * NULL. Then, this waits for being filled the data in a
+ * ring-buffer.
+ */
+ usleep(READ_WAIT_USEC);
+ pr_debug("Read retry(cpu:%d)\n", ts->cpu_num);
+ continue;
+ }
+
+ wlen = 0;
+
+ do {
+ ret = splice(ts->write_pipe, NULL, ts->out_fd, NULL,
+ rlen - wlen,
+ SPLICE_F_MOVE | SPLICE_F_MORE);
+
+ if (ret < 0) {
+ pr_err("Splice_write in rw-thread(%d)\n",
+ ts->cpu_num);
+ goto error;
+ } else if (ret == 0)
+ /*
+ * When host reader is not in time for reading
+ * trace data, guest will be stopped. This is
+ * because char dev in QEMU is not supported
+ * non-blocking mode. Then, writer might be
+ * sleep in that case.
+ * This sleep will be removed by supporting
+ * non-blocking mode.
+ */
+ sleep(1);
+ wlen += ret;
+ } while (wlen < rlen);
+ }
+
+ return NULL;
+
+error:
+ exit(EXIT_FAILURE);
+}
+
+
+pthread_t rw_thread_run(struct rw_thread_info *rw_ti)
+{
+ int ret;
+ pthread_t rw_thread_per_cpu;
+
+ ret = pthread_create(&rw_thread_per_cpu, NULL, rw_thread_main, rw_ti);
+ if (ret != 0) {
+ pr_err("Could not create a rw thread(%d)\n", rw_ti->cpu_num);
+ exit(EXIT_FAILURE);
+ }
+
+ return rw_thread_per_cpu;
+}
diff --git a/tools/virtio/virtio-trace/trace-agent.c b/tools/virtio/virtio-trace/trace-agent.c
new file mode 100644
index 0000000..0a0a7dd
--- /dev/null
+++ b/tools/virtio/virtio-trace/trace-agent.c
@@ -0,0 +1,270 @@
+/*
+ * Guest agent for virtio-trace
+ *
+ * Copyright (C) 2012 Hitachi, Ltd.
+ * Created by Yoshihiro Yunomae <yoshihiro.yunomae.ez@hitachi.com>
+ * Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
+ *
+ * Licensed under GPL version 2 only.
+ *
+ */
+
+#define _GNU_SOURCE
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include "trace-agent.h"
+
+#define PAGE_SIZE (sysconf(_SC_PAGE_SIZE))
+#define PIPE_DEF_BUFS 16
+#define PIPE_MIN_SIZE (PAGE_SIZE*PIPE_DEF_BUFS)
+#define PIPE_MAX_SIZE (1024*1024)
+#define READ_PATH_FMT \
+ "/sys/kernel/debug/tracing/per_cpu/cpu%d/trace_pipe_raw"
+#define WRITE_PATH_FMT "/dev/virtio-ports/trace-path-cpu%d"
+#define CTL_PATH "/dev/virtio-ports/agent-ctl-path"
+
+pthread_mutex_t mutex_notify = PTHREAD_MUTEX_INITIALIZER;
+pthread_cond_t cond_wakeup = PTHREAD_COND_INITIALIZER;
+
+static int get_total_cpus(void)
+{
+ int nr_cpus = (int)sysconf(_SC_NPROCESSORS_CONF);
+
+ if (nr_cpus <= 0) {
+ pr_err("Could not read cpus\n");
+ goto error;
+ } else if (nr_cpus > MAX_CPUS) {
+ pr_err("Exceed max cpus(%d)\n", (int)MAX_CPUS);
+ goto error;
+ }
+
+ return nr_cpus;
+
+error:
+ exit(EXIT_FAILURE);
+}
+
+static void *agent_info_new(void)
+{
+ struct agent_info *s;
+ int i;
+
+ s = zalloc(sizeof(struct agent_info));
+ if (s == NULL) {
+ pr_err("agent_info zalloc error\n");
+ exit(EXIT_FAILURE);
+ }
+
+ s->pipe_size = PIPE_INIT;
+ s->use_stdout = false;
+ s->cpus = get_total_cpus();
+ s->ctl_fd = -1;
+
+ /* read/write threads init */
+ for (i = 0; i < s->cpus; i++)
+ s->rw_ti[i] = rw_thread_info_new();
+
+ return s;
+}
+
+static unsigned long parse_size(const char *arg)
+{
+ unsigned long value, round;
+ char *ptr;
+
+ value = strtoul(arg, &ptr, 10);
+ switch (*ptr) {
+ case 'K': case 'k':
+ value <<= 10;
+ break;
+ case 'M': case 'm':
+ value <<= 20;
+ break;
+ default:
+ break;
+ }
+
+ if (value > PIPE_MAX_SIZE) {
+ pr_err("Pipe size must be less than 1MB\n");
+ goto error;
+ } else if (value < PIPE_MIN_SIZE) {
+ pr_err("Pipe size must be over 64KB\n");
+ goto error;
+ }
+
+ /* Align buffer size with page unit */
+ round = value & (PAGE_SIZE - 1);
+ value = value - round;
+
+ return value;
+error:
+ return 0;
+}
+
+static void usage(char const *prg)
+{
+ pr_err("usage: %s [-h] [-o] [-s <size of pipe>]\n", prg);
+}
+
+static const char *make_path(int cpu_num, bool this_is_write_path)
+{
+ int ret;
+ char *buf;
+
+ buf = zalloc(PATH_MAX);
+ if (buf == NULL) {
+ pr_err("Could not allocate buffer\n");
+ goto error;
+ }
+
+ if (this_is_write_path)
+ /* write(output) path */
+ ret = snprintf(buf, PATH_MAX, WRITE_PATH_FMT, cpu_num);
+ else
+ /* read(input) path */
+ ret = snprintf(buf, PATH_MAX, READ_PATH_FMT, cpu_num);
+
+ if (ret <= 0) {
+ pr_err("Failed to generate %s path(CPU#%d):%d\n",
+ this_is_write_path ? "read" : "write", cpu_num, ret);
+ goto error;
+ }
+
+ return buf;
+
+error:
+ free(buf);
+ return NULL;
+}
+
+static const char *make_input_path(int cpu_num)
+{
+ return make_path(cpu_num, false);
+}
+
+static const char *make_output_path(int cpu_num)
+{
+ return make_path(cpu_num, true);
+}
+
+static void *agent_info_init(struct agent_info *s)
+{
+ int cpu;
+ const char *in_path = NULL;
+ const char *out_path = NULL;
+
+ /* init read/write threads */
+ for (cpu = 0; cpu < s->cpus; cpu++) {
+ /* set read(input) path per read/write thread */
+ in_path = make_input_path(cpu);
+ if (in_path == NULL)
+ goto error;
+
+ /* set write(output) path per read/write thread*/
+ if (!s->use_stdout) {
+ out_path = make_output_path(cpu);
+ if (out_path == NULL)
+ goto error;
+ } else
+ /* stdout mode */
+ pr_debug("stdout mode\n");
+
+ rw_thread_init(cpu, in_path, out_path, s->use_stdout,
+ s->pipe_size, s->rw_ti[cpu]);
+ }
+
+ /* init controller of read/write threads */
+ s->ctl_fd = rw_ctl_init((const char *)CTL_PATH);
+
+ return NULL;
+
+error:
+ exit(EXIT_FAILURE);
+}
+
+static void *parse_args(int argc, char *argv[], struct agent_info *s)
+{
+ int cmd;
+ unsigned long size;
+
+ while ((cmd = getopt(argc, argv, "hos:")) != -1) {
+ switch (cmd) {
+ /* stdout mode */
+ case 'o':
+ s->use_stdout = true;
+ break;
+ /* size of pipe */
+ case 's':
+ size = parse_size(optarg);
+ if (size == 0)
+ goto error;
+ s->pipe_size = size;
+ break;
+ case 'h':
+ default:
+ usage(argv[0]);
+ goto error;
+ }
+ }
+
+ agent_info_init(s);
+
+ return NULL;
+
+error:
+ exit(EXIT_FAILURE);
+}
+
+static void agent_main_loop(struct agent_info *s)
+{
+ int cpu;
+ pthread_t rw_thread_per_cpu[MAX_CPUS];
+
+ /* Start all read/write threads */
+ for (cpu = 0; cpu < s->cpus; cpu++)
+ rw_thread_per_cpu[cpu] = rw_thread_run(s->rw_ti[cpu]);
+
+ rw_ctl_loop(s->ctl_fd);
+
+ /* Finish all read/write threads */
+ for (cpu = 0; cpu < s->cpus; cpu++) {
+ int ret;
+
+ ret = pthread_join(rw_thread_per_cpu[cpu], NULL);
+ if (ret != 0) {
+ pr_err("pthread_join() error:%d (cpu %d)\n", ret, cpu);
+ exit(EXIT_FAILURE);
+ }
+ }
+}
+
+static void agent_info_free(struct agent_info *s)
+{
+ int i;
+
+ close(s->ctl_fd);
+ for (i = 0; i < s->cpus; i++) {
+ close(s->rw_ti[i]->in_fd);
+ close(s->rw_ti[i]->out_fd);
+ close(s->rw_ti[i]->read_pipe);
+ close(s->rw_ti[i]->write_pipe);
+ free(s->rw_ti[i]);
+ }
+ free(s);
+}
+
+int main(int argc, char *argv[])
+{
+ struct agent_info *s = NULL;
+
+ s = agent_info_new();
+ parse_args(argc, argv, s);
+
+ agent_main_loop(s);
+
+ agent_info_free(s);
+
+ return 0;
+}
diff --git a/tools/virtio/virtio-trace/trace-agent.h b/tools/virtio/virtio-trace/trace-agent.h
new file mode 100644
index 0000000..8de79bf
--- /dev/null
+++ b/tools/virtio/virtio-trace/trace-agent.h
@@ -0,0 +1,75 @@
+#ifndef __TRACE_AGENT_H__
+#define __TRACE_AGENT_H__
+#include <pthread.h>
+#include <stdbool.h>
+
+#define MAX_CPUS 256
+#define PIPE_INIT (1024*1024)
+
+/*
+ * agent_info - structure managing total information of guest agent
+ * @pipe_size: size of pipe (default 1MB)
+ * @use_stdout: set to true when o option is added (default false)
+ * @cpus: total number of CPUs
+ * @ctl_fd: fd of control path, /dev/virtio-ports/agent-ctl-path
+ * @rw_ti: structure managing information of read/write threads
+ */
+struct agent_info {
+ unsigned long pipe_size;
+ bool use_stdout;
+ int cpus;
+ int ctl_fd;
+ struct rw_thread_info *rw_ti[MAX_CPUS];
+};
+
+/*
+ * rw_thread_info - structure managing a read/write thread a cpu
+ * @cpu_num: cpu number operating this read/write thread
+ * @in_fd: fd of reading trace data path in cpu_num
+ * @out_fd: fd of writing trace data path in cpu_num
+ * @read_pipe: fd of read pipe
+ * @write_pipe: fd of write pipe
+ * @pipe_size: size of pipe (default 1MB)
+ */
+struct rw_thread_info {
+ int cpu_num;
+ int in_fd;
+ int out_fd;
+ int read_pipe;
+ int write_pipe;
+ unsigned long pipe_size;
+};
+
+/* use for stopping rw threads */
+extern bool global_sig_receive;
+
+/* use for notification */
+extern bool global_run_operation;
+extern pthread_mutex_t mutex_notify;
+extern pthread_cond_t cond_wakeup;
+
+/* for controller of read/write threads */
+extern int rw_ctl_init(const char *ctl_path);
+extern void *rw_ctl_loop(int ctl_fd);
+
+/* for trace read/write thread */
+extern void *rw_thread_info_new(void);
+extern void *rw_thread_init(int cpu, const char *in_path, const char *out_path,
+ bool stdout_flag, unsigned long pipe_size,
+ struct rw_thread_info *rw_ti);
+extern pthread_t rw_thread_run(struct rw_thread_info *rw_ti);
+
+static inline void *zalloc(size_t size)
+{
+ return calloc(1, size);
+}
+
+#define pr_err(format, ...) fprintf(stderr, format, ## __VA_ARGS__)
+#define pr_info(format, ...) fprintf(stdout, format, ## __VA_ARGS__)
+#ifdef DEBUG
+#define pr_debug(format, ...) fprintf(stderr, format, ## __VA_ARGS__)
+#else
+#define pr_debug(format, ...) do {} while (0)
+#endif
+
+#endif /*__TRACE_AGENT_H__*/