diff options
| -rw-r--r-- | block/blk-sysfs.c | 8 | ||||
| -rw-r--r-- | block/elevator.c | 12 |
2 files changed, 18 insertions, 2 deletions
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index e0a70d26972b..af12526d866a 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -78,8 +78,14 @@ queue_requests_store(struct gendisk *disk, const char *page, size_t count) /* * Serialize updating nr_requests with concurrent queue_requests_store() * and switching elevator. + * + * Use trylock to avoid circular lock dependency with kernfs active + * reference during concurrent disk deletion: + * update_nr_hwq_lock -> kn->active (via del_gendisk -> kobject_del) + * kn->active -> update_nr_hwq_lock (via this sysfs write path) */ - down_write(&set->update_nr_hwq_lock); + if (!down_write_trylock(&set->update_nr_hwq_lock)) + return -EBUSY; if (nr == q->nr_requests) goto unlock; diff --git a/block/elevator.c b/block/elevator.c index a2f8b2251dc6..7a97998cd8bd 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -806,7 +806,16 @@ ssize_t elv_iosched_store(struct gendisk *disk, const char *buf, elv_iosched_load_module(ctx.name); ctx.type = elevator_find_get(ctx.name); - down_read(&set->update_nr_hwq_lock); + /* + * Use trylock to avoid circular lock dependency with kernfs active + * reference during concurrent disk deletion: + * update_nr_hwq_lock -> kn->active (via del_gendisk -> kobject_del) + * kn->active -> update_nr_hwq_lock (via this sysfs write path) + */ + if (!down_read_trylock(&set->update_nr_hwq_lock)) { + ret = -EBUSY; + goto out; + } if (!blk_queue_no_elv_switch(q)) { ret = elevator_change(q, &ctx); if (!ret) @@ -816,6 +825,7 @@ ssize_t elv_iosched_store(struct gendisk *disk, const char *buf, } up_read(&set->update_nr_hwq_lock); +out: if (ctx.type) elevator_put(ctx.type); return ret; |