[PATCH] block: aoe: fix page fault in freedev()

[Valentin Kleibel <valentin@vrvis.at>]

There is a bug in the aoe driver module where every forcible removal of 
an aoe device (eg. "rmmod aoe" with aoe devices available or "aoe-flush 
ex.x") leads to a page fault.
The code in freedev() calls blk_mq_free_tag_set() before running 
blk_cleanup_queue() which leads to this issue 
(drivers/block/aoe/aoedev.c L281ff).
This issue was fixed upstream in commit 6560ec9 (aoe: use 
blk_mq_alloc_disk and blk_cleanup_disk) with the introduction and use of 
the function blk_cleanup_disk().

This patch applies to kernels 5.4 and 5.10.

The function calls are reordered to match the behavior of 
blk_cleanup_disk() to mitigate this issue.

Fixes: 3582dd2 (aoe: convert aoeblk to blk-mq)
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=215647
Signed-off-by: Valentin Kleibel <valentin@vrvis.at>
---
  drivers/block/aoe/aoedev.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/block/aoe/aoedev.c b/drivers/block/aoe/aoedev.c
index e2ea2356da06..08c98ea724ea 100644
--- a/drivers/block/aoe/aoedev.c
+++ b/drivers/block/aoe/aoedev.c
@@ -277,9 +277,9 @@ freedev(struct aoedev *d)
         if (d->gd) {
                 aoedisk_rm_debugfs(d);
                 del_gendisk(d->gd);
+               blk_cleanup_queue(d->blkq);
                 put_disk(d->gd);
                 blk_mq_free_tag_set(&d->tag_set);
-               blk_cleanup_queue(d->blkq);
         }
         t = d->targets;
         e = t + d->ntargets;