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Commit 0b8c9de0 authored by NeilBrown's avatar NeilBrown Committed by Linus Torvalds
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[PATCH] md: delay starting md threads until array is completely setup 



When an array is started we start one or two threads (two if there is a
reshape or recovery that needs to be completed).

We currently start these *before* the array is completely set up and in
particular before queue->queuedata is set.  If the thread actually starts
very quickly on another CPU, we can end up dereferencing queue->queuedata
and oops.

This patch also makes sure we don't try to start a recovery if a reshape is
being restarted.

Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 31b65a0d

drivers/md/md.c

+4 −4
Original line number Diff line number Diff line
@@ -3095,7 +3095,6 @@ static int do_md_run(mddev_t * mddev) 
		}

	

	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);

	md_wakeup_thread(mddev->thread);

	

	if (mddev->sb_dirty)

		md_update_sb(mddev);
@@ -3116,7 +3115,7 @@ static int do_md_run(mddev_t * mddev) 
	 * start recovery here.  If we leave it to md_check_recovery,

	 * it will remove the drives and not do the right thing

	 */

	if (mddev->degraded) {

	if (mddev->degraded && !mddev->sync_thread) {

		struct list_head *rtmp;

		int spares = 0;

		ITERATE_RDEV(mddev,rdev,rtmp)
@@ -3137,10 +3136,11 @@ static int do_md_run(mddev_t * mddev) 
				       mdname(mddev));

				/* leave the spares where they are, it shouldn't hurt */

				mddev->recovery = 0;

			} else

				md_wakeup_thread(mddev->sync_thread);

			}

		}

	}

	md_wakeup_thread(mddev->thread);

	md_wakeup_thread(mddev->sync_thread); /* possibly kick off a reshape */



	mddev->changed = 1;

	md_new_event(mddev);

drivers/md/raid5.c

+0 −3
Original line number Diff line number Diff line
@@ -3246,9 +3246,6 @@ static int run(mddev_t *mddev) 
		set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);

		mddev->sync_thread = md_register_thread(md_do_sync, mddev,

							"%s_reshape");

		/* FIXME if md_register_thread fails?? */

		md_wakeup_thread(mddev->sync_thread);



	}



	/* read-ahead size must cover two whole stripes, which is