dect/linux-2.6
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drbd: Fixed inc_ap_bio()

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The condition must be checked after perpare_to_wait(). The old
implementaion could loose wakeup events. Never observed in real
life.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
This commit is contained in:
Philipp Reisner 2010-11-17 18:24:19 +01:00
parent 127b317844
commit 8869d683b7
1 changed files with 14 additions and 17 deletions
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31
drivers/block/drbd/drbd_int.h
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@ -2309,15 +2309,21 @@ static inline int __inc_ap_bio_cond(struct drbd_conf *mdev)
return 1;
}
/* I'd like to use wait_event_lock_irq,
* but I'm not sure when it got introduced,
* and not sure when it has 3 or 4 arguments */
static inline int _inc_ap_bio_cond(struct drbd_conf *mdev, int count)
{
int rv = 0;
spin_lock_irq(&mdev->req_lock);
rv = __inc_ap_bio_cond(mdev);
if (rv)
atomic_add(count, &mdev->ap_bio_cnt);
spin_unlock_irq(&mdev->req_lock);
return rv;
}
static inline void inc_ap_bio(struct drbd_conf *mdev, int count)
{
/* compare with after_state_ch,
* os.conn != C_WF_BITMAP_S && ns.conn == C_WF_BITMAP_S */
DEFINE_WAIT(wait);
/* we wait here
* as long as the device is suspended
* until the bitmap is no longer on the fly during connection
@ -2326,16 +2332,7 @@ static inline void inc_ap_bio(struct drbd_conf *mdev, int count)
* to avoid races with the reconnect code,
* we need to atomic_inc within the spinlock. */
spin_lock_irq(&mdev->req_lock);
while (!__inc_ap_bio_cond(mdev)) {
prepare_to_wait(&mdev->misc_wait, &wait, TASK_UNINTERRUPTIBLE);
spin_unlock_irq(&mdev->req_lock);
schedule();
finish_wait(&mdev->misc_wait, &wait);
spin_lock_irq(&mdev->req_lock);
}
atomic_add(count, &mdev->ap_bio_cnt);
spin_unlock_irq(&mdev->req_lock);
wait_event(mdev->misc_wait, _inc_ap_bio_cond(mdev, count));
}
static inline void dec_ap_bio(struct drbd_conf *mdev)