[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: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 9f76e0c..fb50e56 100644 (file)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -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);

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 5764387..a02f35f 100644 (file)
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -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