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Commit 8869d683 authored by Philipp Reisner's avatar Philipp Reisner
Browse files

drbd: Fixed inc_ap_bio() 



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

Signed-off-by: default avatarPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: default avatarLars Ellenberg <lars.ellenberg@linbit.com>
parent 127b3178

drivers/block/drbd/drbd_int.h

+14 −17
Original line number Diff line number Diff line
@@ -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 void inc_ap_bio(struct drbd_conf *mdev, int count)

static inline int _inc_ap_bio_cond(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);

	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)

{

	/* 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)