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authorSuleiman Souhlal <suleiman@google.com>2007-04-10 22:38:37 +0200
committerBartlomiej Zolnierkiewicz <bzolnier@gmail.com>2007-04-10 22:38:37 +0200
commit23450319e2890986c247ec0aa1442f060e657e6d (patch)
treec30fc173d8b97343f8ae7b1b1ed511366af256ab
parent90f30eccf41302a2542f5d374af243061902bd98 (diff)
ide: correctly prevent IDE timer expiry function to run if request was already handled
It is possible for the timer expiry function to run even though the request has already been handled: ide_timer_expiry() only checks that the handler is not NULL, but it is possible that we have handled a request (thus clearing the handler) and then started a new request (thus starting the timer again, and setting a handler). A simple way to exhibit this is to set the DMA timeout to 1 jiffy and run dd: The kernel will panic after a few minutes because ide_timer_expiry() tries to add a timer when it's already active. To fix this, we simply add a request generation count that gets incremented at every interrupt, and check in ide_timer_expiry() that we have not already handled a new interrupt before running the expiry function. Signed-off-by: Suleiman Souhlal <suleiman@google.com> Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
-rw-r--r--drivers/ide/ide-io.c6
-rw-r--r--drivers/ide/ide-iops.c2
-rw-r--r--include/linux/ide.h2
3 files changed, 9 insertions, 1 deletions
diff --git a/drivers/ide/ide-io.c b/drivers/ide/ide-io.c
index 0e0280076fc..8670112f1d3 100644
--- a/drivers/ide/ide-io.c
+++ b/drivers/ide/ide-io.c
@@ -1226,6 +1226,7 @@ static void ide_do_request (ide_hwgroup_t *hwgroup, int masked_irq)
#endif
/* so that ide_timer_expiry knows what to do */
hwgroup->sleeping = 1;
+ hwgroup->req_gen_timer = hwgroup->req_gen;
mod_timer(&hwgroup->timer, sleep);
/* we purposely leave hwgroup->busy==1
* while sleeping */
@@ -1411,7 +1412,8 @@ void ide_timer_expiry (unsigned long data)
spin_lock_irqsave(&ide_lock, flags);
- if ((handler = hwgroup->handler) == NULL) {
+ if (((handler = hwgroup->handler) == NULL) ||
+ (hwgroup->req_gen != hwgroup->req_gen_timer)) {
/*
* Either a marginal timeout occurred
* (got the interrupt just as timer expired),
@@ -1439,6 +1441,7 @@ void ide_timer_expiry (unsigned long data)
if ((wait = expiry(drive)) > 0) {
/* reset timer */
hwgroup->timer.expires = jiffies + wait;
+ hwgroup->req_gen_timer = hwgroup->req_gen;
add_timer(&hwgroup->timer);
spin_unlock_irqrestore(&ide_lock, flags);
return;
@@ -1653,6 +1656,7 @@ irqreturn_t ide_intr (int irq, void *dev_id)
printk(KERN_ERR "%s: ide_intr: hwgroup->busy was 0 ??\n", drive->name);
}
hwgroup->handler = NULL;
+ hwgroup->req_gen++;
del_timer(&hwgroup->timer);
spin_unlock(&ide_lock);
diff --git a/drivers/ide/ide-iops.c b/drivers/ide/ide-iops.c
index 1ee53a551c3..3caa176b315 100644
--- a/drivers/ide/ide-iops.c
+++ b/drivers/ide/ide-iops.c
@@ -889,6 +889,7 @@ static void __ide_set_handler (ide_drive_t *drive, ide_handler_t *handler,
hwgroup->handler = handler;
hwgroup->expiry = expiry;
hwgroup->timer.expires = jiffies + timeout;
+ hwgroup->req_gen_timer = hwgroup->req_gen;
add_timer(&hwgroup->timer);
}
@@ -929,6 +930,7 @@ void ide_execute_command(ide_drive_t *drive, task_ioreg_t cmd, ide_handler_t *ha
hwgroup->handler = handler;
hwgroup->expiry = expiry;
hwgroup->timer.expires = jiffies + timeout;
+ hwgroup->req_gen_timer = hwgroup->req_gen;
add_timer(&hwgroup->timer);
hwif->OUTBSYNC(drive, cmd, IDE_COMMAND_REG);
/* Drive takes 400nS to respond, we must avoid the IRQ being
diff --git a/include/linux/ide.h b/include/linux/ide.h
index 58564a19986..d3bbc7188b6 100644
--- a/include/linux/ide.h
+++ b/include/linux/ide.h
@@ -861,6 +861,8 @@ typedef struct hwgroup_s {
int (*expiry)(ide_drive_t *);
/* ide_system_bus_speed */
int pio_clock;
+ int req_gen;
+ int req_gen_timer;
unsigned char cmd_buf[4];
} ide_hwgroup_t;