2011-06-04 18:19:45

by Larry Finger

[permalink] [raw]
Subject: In case 3.0-rc1 from wireless-testing fails to boot

When I tried using 3.0-rc1 from mainline, my computer failed to boot because it
got into an infinite loop initiated from user space. Bisection led to a
particular commit, and reverting it "fixed" the problem. In fact, the actual
problem was a faulty merge. This problem is fixed in the current linux-2.6-git,
but that patch is not yet in wireless-testing.

In case you run into this problem, the fix is commit 0f48f2600911d (reproduced
below):


commit 0f48f2600911d5de6393829e4a9986d4075558b3
Author: Linus Torvalds <[email protected]>
Date: Thu Jun 2 05:29:19 2011 +0900

block: fix mismerge of the DISK_EVENT_MEDIA_CHANGE removal

Jens' back-merge commit 698567f3fa79 ("Merge commit 'v2.6.39' into
for-2.6.40/core") was incorrectly done, and re-introduced the
DISK_EVENT_MEDIA_CHANGE lines that had been removed earlier in commits

- 9fd097b14918 ("block: unexport DISK_EVENT_MEDIA_CHANGE for
legacy/fringe drivers")

- 7eec77a1816a ("ide: unexport DISK_EVENT_MEDIA_CHANGE for ide-gd
and ide-cd")

because of conflicts with the "g->flags" updates near-by by commit
d4dc210f69bc ("block: don't block events on excl write for non-optical
devices")

As a result, we re-introduced the hanging behavior due to infinite disk
media change reports.

Tssk, tssk, people! Don't do back-merges at all, and *definitely* don't
do them to hide merge conflicts from me - especially as I'm likely
better at merging them than you are, since I do so many merges.

Reported-by: Steven Rostedt <[email protected]>
Cc: Jens Axboe <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

diff --git a/drivers/block/paride/pcd.c b/drivers/block/paride/pcd.c
index a0aabd9..46b8136 100644
--- a/drivers/block/paride/pcd.c
+++ b/drivers/block/paride/pcd.c
@@ -321,7 +321,6 @@ static void pcd_init_units(void)
strcpy(disk->disk_name, cd->name); /* umm... */
disk->fops = &pcd_bdops;
disk->flags = GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE;
- disk->events = DISK_EVENT_MEDIA_CHANGE;
}
}

diff --git a/drivers/cdrom/viocd.c b/drivers/cdrom/viocd.c
index ae15a4d..7878da8 100644
--- a/drivers/cdrom/viocd.c
+++ b/drivers/cdrom/viocd.c
@@ -627,7 +627,6 @@ static int viocd_probe(struct vio_dev *vdev, const struct
vio_device_id *id)
gendisk->fops = &viocd_fops;
gendisk->flags = GENHD_FL_CD | GENHD_FL_REMOVABLE |
GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE;
- gendisk->events = DISK_EVENT_MEDIA_CHANGE;
set_capacity(gendisk, 0);
gendisk->private_data = d;
d->viocd_disk = gendisk;
diff --git a/drivers/ide/ide-cd.c b/drivers/ide/ide-cd.c
index 6e5123b..144d272 100644
--- a/drivers/ide/ide-cd.c
+++ b/drivers/ide/ide-cd.c
@@ -1782,7 +1782,6 @@ static int ide_cd_probe(ide_drive_t *drive)
ide_cd_read_toc(drive, &sense);
g->fops = &idecd_ops;
g->flags |= GENHD_FL_REMOVABLE | GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE;
- g->events = DISK_EVENT_MEDIA_CHANGE;
add_disk(g);
return 0;