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Subject[PATCH 184/241] floppy: destroy floppy workqueue before cleaning up the queue
Date
3.5.7.2 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jiri Kosina <jkosina@suse.cz>

commit eac7cc52c6b410e542af431b2ee93f3d7dbfb6af upstream.

We need to first destroy the floppy_wq workqueue before cleaning up
the queue. Otherwise we might race with still pending work with the
workqueue, but all the block queue already gone. This might lead to
various oopses, such as

CPU 0
Pid: 6, comm: kworker/u:0 Not tainted 3.7.0-rc4 #1 Bochs Bochs
RIP: 0010:[<ffffffff8134eef5>] [<ffffffff8134eef5>] blk_peek_request+0xd5/0x1c0
RSP: 0000:ffff88000dc7dd88 EFLAGS: 00010092
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff88000f602688 RSI: ffffffff81fd95d8 RDI: 6b6b6b6b6b6b6b6b
RBP: ffff88000dc7dd98 R08: ffffffff81fd95c8 R09: 0000000000000000
R10: ffffffff81fd9480 R11: 0000000000000001 R12: 6b6b6b6b6b6b6b6b
R13: ffff88000dc7dfd8 R14: ffff88000dc7dfd8 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffffffff81e21000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 0000000000000000 CR3: 0000000001e11000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process kworker/u:0 (pid: 6, threadinfo ffff88000dc7c000, task ffff88000dc5ecc0)
Stack:
0000000000000000 0000000000000000 ffff88000dc7ddb8 ffffffff8134efee
ffff88000dc7ddb8 0000000000000000 ffff88000dc7dde8 ffffffff814aef3c
ffffffff81e75d80 ffff88000dc0c640 ffff88000fbfb000 ffffffff814aed90
Call Trace:
[<ffffffff8134efee>] blk_fetch_request+0xe/0x30
[<ffffffff814aef3c>] redo_fd_request+0x1ac/0x400
[<ffffffff814aed90>] ? start_motor+0x130/0x130
[<ffffffff8106b526>] process_one_work+0x136/0x450
[<ffffffff8106af65>] ? manage_workers+0x205/0x2e0
[<ffffffff8106bb6d>] worker_thread+0x14d/0x420
[<ffffffff8106ba20>] ? rescuer_thread+0x1a0/0x1a0
[<ffffffff8107075a>] kthread+0xba/0xc0
[<ffffffff810706a0>] ? __kthread_parkme+0x80/0x80
[<ffffffff818b553a>] ret_from_fork+0x7a/0xb0
[<ffffffff810706a0>] ? __kthread_parkme+0x80/0x80
Code: 0f 84 c0 00 00 00 83 f8 01 0f 85 e2 00 00 00 81 4b 40 00 00 80 00 48 89 df e8 58 f8 ff ff be fb ff ff ff
fe ff ff <49> 8b 1c 24 49 39 dc 0f 85 2e ff ff ff 41 0f b6 84 24 28 04 00
RIP [<ffffffff8134eef5>] blk_peek_request+0xd5/0x1c0
RSP <ffff88000dc7dd88>

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Tested-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
[ herton: adjust context ]
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>
---
drivers/block/floppy.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
index 7ad2489..059315b 100644
--- a/drivers/block/floppy.c
+++ b/drivers/block/floppy.c
@@ -4329,6 +4329,7 @@ out_unreg_region:
out_unreg_blkdev:
unregister_blkdev(FLOPPY_MAJOR, "fd");
out_put_disk:
+ destroy_workqueue(floppy_wq);
while (dr--) {
del_timer_sync(&motor_off_timer[dr]);
if (disks[dr]->queue) {
@@ -4341,7 +4342,6 @@ out_put_disk:
}
put_disk(disks[dr]);
}
- destroy_workqueue(floppy_wq);
return err;
}

@@ -4538,6 +4538,8 @@ static void __exit floppy_module_exit(void)
unregister_blkdev(FLOPPY_MAJOR, "fd");
platform_driver_unregister(&floppy_driver);

+ destroy_workqueue(floppy_wq);
+
for (drive = 0; drive < N_DRIVE; drive++) {
del_timer_sync(&motor_off_timer[drive]);

@@ -4562,7 +4564,6 @@ static void __exit floppy_module_exit(void)

cancel_delayed_work_sync(&fd_timeout);
cancel_delayed_work_sync(&fd_timer);
- destroy_workqueue(floppy_wq);

if (atomic_read(&usage_count))
floppy_release_irq_and_dma();
--
1.7.9.5


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