[PATCH] USB Gadget: file_storage: remove "volatile" declarations
This patch (as612) removes the "volatile" declarations from the
file-storage gadget. It turns out that they aren't needed for anything
much; adding a few memory barriers does a sufficient job.
The patch also removes a wait_queue. Not much point having a queue when
only one task is ever going to be on it!
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/gadget/file_storage.c b/drivers/usb/gadget/file_storage.c
index f6c49b7..0cea978 100644
--- a/drivers/usb/gadget/file_storage.c
+++ b/drivers/usb/gadget/file_storage.c
@@ -239,7 +239,6 @@
#include <linux/string.h>
#include <linux/suspend.h>
#include <linux/utsname.h>
-#include <linux/wait.h>
#include <linux/usb_ch9.h>
#include <linux/usb_gadget.h>
@@ -251,7 +250,7 @@
#define DRIVER_DESC "File-backed Storage Gadget"
#define DRIVER_NAME "g_file_storage"
-#define DRIVER_VERSION "20 October 2004"
+#define DRIVER_VERSION "28 November 2005"
static const char longname[] = DRIVER_DESC;
static const char shortname[] = DRIVER_NAME;
@@ -588,7 +587,7 @@
struct fsg_buffhd {
void *buf;
dma_addr_t dma;
- volatile enum fsg_buffer_state state;
+ enum fsg_buffer_state state;
struct fsg_buffhd *next;
/* The NetChip 2280 is faster, and handles some protocol faults
@@ -597,9 +596,9 @@
unsigned int bulk_out_intended_length;
struct usb_request *inreq;
- volatile int inreq_busy;
+ int inreq_busy;
struct usb_request *outreq;
- volatile int outreq_busy;
+ int outreq_busy;
};
enum fsg_state {
@@ -637,11 +636,11 @@
struct usb_ep *ep0; // Handy copy of gadget->ep0
struct usb_request *ep0req; // For control responses
- volatile unsigned int ep0_req_tag;
+ unsigned int ep0_req_tag;
const char *ep0req_name;
struct usb_request *intreq; // For interrupt responses
- volatile int intreq_busy;
+ int intreq_busy;
struct fsg_buffhd *intr_buffhd;
unsigned int bulk_out_maxpacket;
@@ -671,7 +670,6 @@
struct fsg_buffhd *next_buffhd_to_drain;
struct fsg_buffhd buffhds[NUM_BUFFERS];
- wait_queue_head_t thread_wqh;
int thread_wakeup_needed;
struct completion thread_notifier;
struct task_struct *thread_task;
@@ -1076,11 +1074,13 @@
/* These routines may be called in process context or in_irq */
+/* Caller must hold fsg->lock */
static void wakeup_thread(struct fsg_dev *fsg)
{
/* Tell the main thread that something has happened */
fsg->thread_wakeup_needed = 1;
- wake_up_all(&fsg->thread_wqh);
+ if (fsg->thread_task)
+ wake_up_process(fsg->thread_task);
}
@@ -1167,11 +1167,12 @@
usb_ep_fifo_flush(ep);
/* Hold the lock while we update the request and buffer states */
+ smp_wmb();
spin_lock(&fsg->lock);
bh->inreq_busy = 0;
bh->state = BUF_STATE_EMPTY;
- spin_unlock(&fsg->lock);
wakeup_thread(fsg);
+ spin_unlock(&fsg->lock);
}
static void bulk_out_complete(struct usb_ep *ep, struct usb_request *req)
@@ -1188,11 +1189,12 @@
usb_ep_fifo_flush(ep);
/* Hold the lock while we update the request and buffer states */
+ smp_wmb();
spin_lock(&fsg->lock);
bh->outreq_busy = 0;
bh->state = BUF_STATE_FULL;
- spin_unlock(&fsg->lock);
wakeup_thread(fsg);
+ spin_unlock(&fsg->lock);
}
@@ -1209,11 +1211,12 @@
usb_ep_fifo_flush(ep);
/* Hold the lock while we update the request and buffer states */
+ smp_wmb();
spin_lock(&fsg->lock);
fsg->intreq_busy = 0;
bh->state = BUF_STATE_EMPTY;
- spin_unlock(&fsg->lock);
wakeup_thread(fsg);
+ spin_unlock(&fsg->lock);
}
#else
@@ -1264,8 +1267,8 @@
fsg->cbbuf_cmnd_size = req->actual;
memcpy(fsg->cbbuf_cmnd, req->buf, fsg->cbbuf_cmnd_size);
- spin_unlock(&fsg->lock);
wakeup_thread(fsg);
+ spin_unlock(&fsg->lock);
}
#else
@@ -1517,8 +1520,8 @@
/* Use this for bulk or interrupt transfers, not ep0 */
static void start_transfer(struct fsg_dev *fsg, struct usb_ep *ep,
- struct usb_request *req, volatile int *pbusy,
- volatile enum fsg_buffer_state *state)
+ struct usb_request *req, int *pbusy,
+ enum fsg_buffer_state *state)
{
int rc;
@@ -1526,8 +1529,11 @@
dump_msg(fsg, "bulk-in", req->buf, req->length);
else if (ep == fsg->intr_in)
dump_msg(fsg, "intr-in", req->buf, req->length);
+
+ spin_lock_irq(&fsg->lock);
*pbusy = 1;
*state = BUF_STATE_BUSY;
+ spin_unlock_irq(&fsg->lock);
rc = usb_ep_queue(ep, req, GFP_KERNEL);
if (rc != 0) {
*pbusy = 0;
@@ -1547,14 +1553,23 @@
static int sleep_thread(struct fsg_dev *fsg)
{
- int rc;
+ int rc = 0;
/* Wait until a signal arrives or we are woken up */
- rc = wait_event_interruptible(fsg->thread_wqh,
- fsg->thread_wakeup_needed);
+ for (;;) {
+ try_to_freeze();
+ set_current_state(TASK_INTERRUPTIBLE);
+ if (signal_pending(current)) {
+ rc = -EINTR;
+ break;
+ }
+ if (fsg->thread_wakeup_needed)
+ break;
+ schedule();
+ }
+ __set_current_state(TASK_RUNNING);
fsg->thread_wakeup_needed = 0;
- try_to_freeze();
- return (rc ? -EINTR : 0);
+ return rc;
}
@@ -1791,6 +1806,7 @@
if (bh->state == BUF_STATE_EMPTY && !get_some_more)
break; // We stopped early
if (bh->state == BUF_STATE_FULL) {
+ smp_rmb();
fsg->next_buffhd_to_drain = bh->next;
bh->state = BUF_STATE_EMPTY;
@@ -2359,6 +2375,7 @@
/* Throw away the data in a filled buffer */
if (bh->state == BUF_STATE_FULL) {
+ smp_rmb();
bh->state = BUF_STATE_EMPTY;
fsg->next_buffhd_to_drain = bh->next;
@@ -3024,6 +3041,7 @@
if ((rc = sleep_thread(fsg)) != 0)
return rc;
}
+ smp_rmb();
rc = received_cbw(fsg, bh);
bh->state = BUF_STATE_EMPTY;
@@ -4072,7 +4090,6 @@
spin_lock_init(&fsg->lock);
init_rwsem(&fsg->filesem);
kref_init(&fsg->ref);
- init_waitqueue_head(&fsg->thread_wqh);
init_completion(&fsg->thread_notifier);
the_fsg = fsg;