From: Tetsuo Handa penguin-kernel@i-love.sakura.ne.jp
[ Upstream commit 4ddb85d36613c45bde00d368bf9f357bd0708a0c ]
Commit bf9c0538e485b591 ("ataflop: use a separate gendisk for each media format") introduced ataflop_probe_lock mutex, but forgot to unlock the mutex when atari_floppy_init() (i.e. module loading) succeeded. This will result in double lock deadlock if ataflop_probe() is called. Also, unregister_blkdev() must not be called from atari_floppy_init() with ataflop_probe_lock held when atari_floppy_init() failed, for ataflop_probe() waits for ataflop_probe_lock with major_names_lock held (i.e. AB-BA deadlock).
__register_blkdev() needs to be called last in order to avoid calling ataflop_probe() when atari_floppy_init() is about to fail, for memory for completing already-started ataflop_probe() safely will be released as soon as atari_floppy_init() released ataflop_probe_lock mutex.
As with commit 8b52d8be86d72308 ("loop: reorder loop_exit"), unregister_blkdev() needs to be called first in order to avoid calling ataflop_alloc_disk() from ataflop_probe() after del_gendisk() from atari_floppy_exit().
By relocating __register_blkdev() / unregister_blkdev() as explained above, we can remove ataflop_probe_lock mutex, for probe function and __exit function are serialized by major_names_lock mutex.
Signed-off-by: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp Fixes: bf9c0538e485b591 ("ataflop: use a separate gendisk for each media format") Reviewed-by: Luis Chamberlain mcgrof@kernel.org Tested-by: Michael Schmitz schmitzmic@gmail.com Link: https://lore.kernel.org/r/20211103230437.1639990-11-mcgrof@kernel.org Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/block/ataflop.c | 47 +++++++++++++++++++++++------------------ 1 file changed, 27 insertions(+), 20 deletions(-)
diff --git a/drivers/block/ataflop.c b/drivers/block/ataflop.c index 2d3a66362dcf9..3a29f1992d971 100644 --- a/drivers/block/ataflop.c +++ b/drivers/block/ataflop.c @@ -2016,8 +2016,6 @@ static int ataflop_alloc_disk(unsigned int drive, unsigned int type) return 0; }
-static DEFINE_MUTEX(ataflop_probe_lock); - static void ataflop_probe(dev_t dev) { int drive = MINOR(dev) & 3; @@ -2025,14 +2023,32 @@ static void ataflop_probe(dev_t dev)
if (drive >= FD_MAX_UNITS || type > NUM_DISK_MINORS) return; - mutex_lock(&ataflop_probe_lock); if (!unit[drive].disk[type]) { if (ataflop_alloc_disk(drive, type) == 0) { add_disk(unit[drive].disk[type]); unit[drive].registered[type] = true; } } - mutex_unlock(&ataflop_probe_lock); +} + +static void atari_floppy_cleanup(void) +{ + int i; + int type; + + for (i = 0; i < FD_MAX_UNITS; i++) { + for (type = 0; type < NUM_DISK_MINORS; type++) { + if (!unit[i].disk[type]) + continue; + del_gendisk(unit[i].disk[type]); + blk_cleanup_queue(unit[i].disk[type]->queue); + put_disk(unit[i].disk[type]); + } + blk_mq_free_tag_set(&unit[i].tag_set); + } + + del_timer_sync(&fd_timer); + atari_stram_free(DMABuffer); }
static void atari_cleanup_floppy_disk(struct atari_floppy_struct *fs) @@ -2058,11 +2074,6 @@ static int __init atari_floppy_init (void) /* Amiga, Mac, ... don't have Atari-compatible floppy :-) */ return -ENODEV;
- mutex_lock(&ataflop_probe_lock); - ret = __register_blkdev(FLOPPY_MAJOR, "fd", ataflop_probe); - if (ret) - goto out_unlock; - for (i = 0; i < FD_MAX_UNITS; i++) { memset(&unit[i].tag_set, 0, sizeof(unit[i].tag_set)); unit[i].tag_set.ops = &ataflop_mq_ops; @@ -2116,15 +2127,17 @@ static int __init atari_floppy_init (void) UseTrackbuffer ? "" : "no "); config_types();
- return 0; + ret = __register_blkdev(FLOPPY_MAJOR, "fd", ataflop_probe); + if (ret) { + printk(KERN_ERR "atari_floppy_init: cannot register block device\n"); + atari_floppy_cleanup(); + } + return ret;
err: while (--i >= 0) atari_cleanup_floppy_disk(&unit[i]);
- unregister_blkdev(FLOPPY_MAJOR, "fd"); -out_unlock: - mutex_unlock(&ataflop_probe_lock); return ret; }
@@ -2169,14 +2182,8 @@ __setup("floppy=", atari_floppy_setup);
static void __exit atari_floppy_exit(void) { - int i; - - for (i = 0; i < FD_MAX_UNITS; i++) - atari_cleanup_floppy_disk(&unit[i]); unregister_blkdev(FLOPPY_MAJOR, "fd"); - - del_timer_sync(&fd_timer); - atari_stram_free( DMABuffer ); + atari_floppy_cleanup(); }
module_init(atari_floppy_init)