Commits
Bart Van Assche committed 624fa7790f8
scsi: klist: Make it safe to use klists in atomic context
In the scsi_transport_srp implementation it cannot be avoided to
iterate over a klist from atomic context when using the legacy block
layer instead of blk-mq. Hence this patch that makes it safe to use
klists in atomic context. This patch avoids that lockdep reports the
following:
WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected
Possible interrupt unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&(&k->k_lock)->rlock);
local_irq_disable();
lock(&(&q->__queue_lock)->rlock);
lock(&(&k->k_lock)->rlock);
<Interrupt>
lock(&(&q->__queue_lock)->rlock);
stack backtrace:
Workqueue: kblockd blk_timeout_work
Call Trace:
dump_stack+0xa4/0xf5
check_usage+0x6e6/0x700
__lock_acquire+0x185d/0x1b50
lock_acquire+0xd2/0x260
_raw_spin_lock+0x32/0x50
klist_next+0x47/0x190
device_for_each_child+0x8e/0x100
srp_timed_out+0xaf/0x1d0 [scsi_transport_srp]
scsi_times_out+0xd4/0x410 [scsi_mod]
blk_rq_timed_out+0x36/0x70
blk_timeout_work+0x1b5/0x220
process_one_work+0x4fe/0xad0
worker_thread+0x63/0x5a0
kthread+0x1c1/0x1e0
ret_from_fork+0x24/0x30
See also commit c9ddf73476ff ("scsi: scsi_transport_srp: Fix shost to
rport translation").
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: James Bottomley <jejb@linux.vnet.ibm.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>