hvc_console: rework setup to replace irq functions with callbacks
This patch tries to change hvc_console to not use request_irq/free_irq if
the backend does not use irqs. This allows virtio_console to use hvc_console
without having a linker reference to request_irq/free_irq.
In addition, together with patch 2/3 it improves the performance for virtio
console input. (an earlier version of this patch was tested by Yajin on lguest)
The irq specific code is moved to hvc_irq.c and selected by the drivers that
use irqs (System p, System i, XEN).
I replaced "int irq" with the opaque "int data". The request_irq and
free_irq calls are replaced with notifier_add and notifier_del. I have also
changed the code a bit to call the notifier_add and notifier_del inside the
spinlock area as the callbacks are found via hp->ops.
Changes since last version:
o remove ifdef
o reintroduce "irq_requested" as "notified"
o cleanups, sparse..
I did not move the timer based polling into a separate polling scheme. I
played with several variants, but it seems we need to sleep/schedule in
a thread even for irq based consoles, as there are throttleing and buffer
size constraints.
I also kept hvc_struct defined in hvc_console.h so that hvc_irq.c can access
the irq_requested element.
Feedback is appreciated. virtio_console is currently the only available console
for kvm on s390. I plan to push this change as soon as all affected parties
agree on it. I would love to get test results from System p, Xen etc.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
diff --git a/drivers/char/hvc_console.c b/drivers/char/hvc_console.c
index 2f9759d..2f5b7fb 100644
--- a/drivers/char/hvc_console.c
+++ b/drivers/char/hvc_console.c
@@ -27,7 +27,6 @@
#include <linux/init.h>
#include <linux/kbd_kern.h>
#include <linux/kernel.h>
-#include <linux/kref.h>
#include <linux/kthread.h>
#include <linux/list.h>
#include <linux/module.h>
@@ -75,23 +74,6 @@
static int sysrq_pressed;
#endif
-struct hvc_struct {
- spinlock_t lock;
- int index;
- struct tty_struct *tty;
- unsigned int count;
- int do_wakeup;
- char *outbuf;
- int outbuf_size;
- int n_outbuf;
- uint32_t vtermno;
- struct hv_ops *ops;
- int irq_requested;
- int irq;
- struct list_head next;
- struct kref kref; /* ref count & hvc_struct lifetime */
-};
-
/* dynamic list of hvc_struct instances */
static LIST_HEAD(hvc_structs);
@@ -300,26 +282,12 @@
}
/* Wake the sleeping khvcd */
-static void hvc_kick(void)
+void hvc_kick(void)
{
hvc_kicked = 1;
wake_up_process(hvc_task);
}
-static int hvc_poll(struct hvc_struct *hp);
-
-/*
- * NOTE: This API isn't used if the console adapter doesn't support interrupts.
- * In this case the console is poll driven.
- */
-static irqreturn_t hvc_handle_interrupt(int irq, void *dev_instance)
-{
- /* if hvc_poll request a repoll, then kick the hvcd thread */
- if (hvc_poll(dev_instance))
- hvc_kick();
- return IRQ_HANDLED;
-}
-
static void hvc_unthrottle(struct tty_struct *tty)
{
hvc_kick();
@@ -333,7 +301,6 @@
{
struct hvc_struct *hp;
unsigned long flags;
- int irq = 0;
int rc = 0;
/* Auto increments kref reference if found. */
@@ -352,18 +319,15 @@
tty->low_latency = 1; /* Makes flushes to ldisc synchronous. */
hp->tty = tty;
- /* Save for request_irq outside of spin_lock. */
- irq = hp->irq;
- if (irq)
- hp->irq_requested = 1;
+
+ if (hp->ops->notifier_add)
+ rc = hp->ops->notifier_add(hp, hp->data);
spin_unlock_irqrestore(&hp->lock, flags);
- /* check error, fallback to non-irq */
- if (irq)
- rc = request_irq(irq, hvc_handle_interrupt, IRQF_DISABLED, "hvc_console", hp);
+
/*
- * If the request_irq() fails and we return an error. The tty layer
+ * If the notifier fails we return an error. The tty layer
* will call hvc_close() after a failed open but we don't want to clean
* up there so we'll clean up here and clear out the previously set
* tty fields and return the kref reference.
@@ -371,7 +335,6 @@
if (rc) {
spin_lock_irqsave(&hp->lock, flags);
hp->tty = NULL;
- hp->irq_requested = 0;
spin_unlock_irqrestore(&hp->lock, flags);
tty->driver_data = NULL;
kref_put(&hp->kref, destroy_hvc_struct);
@@ -386,7 +349,6 @@
static void hvc_close(struct tty_struct *tty, struct file * filp)
{
struct hvc_struct *hp;
- int irq = 0;
unsigned long flags;
if (tty_hung_up_p(filp))
@@ -404,9 +366,8 @@
spin_lock_irqsave(&hp->lock, flags);
if (--hp->count == 0) {
- if (hp->irq_requested)
- irq = hp->irq;
- hp->irq_requested = 0;
+ if (hp->ops->notifier_del)
+ hp->ops->notifier_del(hp, hp->data);
/* We are done with the tty pointer now. */
hp->tty = NULL;
@@ -418,10 +379,6 @@
* waking periodically to check chars_in_buffer().
*/
tty_wait_until_sent(tty, HVC_CLOSE_WAIT);
-
- if (irq)
- free_irq(irq, hp);
-
} else {
if (hp->count < 0)
printk(KERN_ERR "hvc_close %X: oops, count is %d\n",
@@ -436,7 +393,6 @@
{
struct hvc_struct *hp = tty->driver_data;
unsigned long flags;
- int irq = 0;
int temp_open_count;
if (!hp)
@@ -458,13 +414,12 @@
hp->count = 0;
hp->n_outbuf = 0;
hp->tty = NULL;
- if (hp->irq_requested)
- /* Saved for use outside of spin_lock. */
- irq = hp->irq;
- hp->irq_requested = 0;
+
+ if (hp->ops->notifier_del)
+ hp->ops->notifier_del(hp, hp->data);
+
spin_unlock_irqrestore(&hp->lock, flags);
- if (irq)
- free_irq(irq, hp);
+
while(temp_open_count) {
--temp_open_count;
kref_put(&hp->kref, destroy_hvc_struct);
@@ -575,7 +530,7 @@
#define HVC_POLL_READ 0x00000001
#define HVC_POLL_WRITE 0x00000002
-static int hvc_poll(struct hvc_struct *hp)
+int hvc_poll(struct hvc_struct *hp)
{
struct tty_struct *tty;
int i, n, poll_mask = 0;
@@ -602,10 +557,10 @@
if (test_bit(TTY_THROTTLED, &tty->flags))
goto throttled;
- /* If we aren't interrupt driven and aren't throttled, we always
+ /* If we aren't notifier driven and aren't throttled, we always
* request a reschedule
*/
- if (hp->irq == 0)
+ if (!hp->irq_requested)
poll_mask |= HVC_POLL_READ;
/* Read data if any */
@@ -733,7 +688,7 @@
.chars_in_buffer = hvc_chars_in_buffer,
};
-struct hvc_struct __devinit *hvc_alloc(uint32_t vtermno, int irq,
+struct hvc_struct __devinit *hvc_alloc(uint32_t vtermno, int data,
struct hv_ops *ops, int outbuf_size)
{
struct hvc_struct *hp;
@@ -754,7 +709,7 @@
memset(hp, 0x00, sizeof(*hp));
hp->vtermno = vtermno;
- hp->irq = irq;
+ hp->data = data;
hp->ops = ops;
hp->outbuf_size = outbuf_size;
hp->outbuf = &((char *)hp)[ALIGN(sizeof(*hp), sizeof(long))];