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| author | Bart Van Assche <bart.vanassche@wdc.com> | 2018-06-22 14:54:49 -0700 |
|---|---|---|
| committer | Martin K. Petersen <martin.petersen@oracle.com> | 2018-07-02 16:20:23 -0400 |
| commit | 624fa7790f80575a4ec28fbdb2034097dc18d051 (patch) | |
| tree | 841d959df00321213c77f0faf9548b3cb2457dd8 | |
| parent | 68c3f904ed4591797ccac22148b95c54af391f30 (diff) | |
| download | lwn-624fa7790f80575a4ec28fbdb2034097dc18d051.tar.gz lwn-624fa7790f80575a4ec28fbdb2034097dc18d051.zip | |
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>
| -rw-r--r-- | lib/klist.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/lib/klist.c b/lib/klist.c index 0507fa5d84c5..f6b547812fe3 100644 --- a/lib/klist.c +++ b/lib/klist.c @@ -336,8 +336,9 @@ struct klist_node *klist_prev(struct klist_iter *i) void (*put)(struct klist_node *) = i->i_klist->put; struct klist_node *last = i->i_cur; struct klist_node *prev; + unsigned long flags; - spin_lock(&i->i_klist->k_lock); + spin_lock_irqsave(&i->i_klist->k_lock, flags); if (last) { prev = to_klist_node(last->n_node.prev); @@ -356,7 +357,7 @@ struct klist_node *klist_prev(struct klist_iter *i) prev = to_klist_node(prev->n_node.prev); } - spin_unlock(&i->i_klist->k_lock); + spin_unlock_irqrestore(&i->i_klist->k_lock, flags); if (put && last) put(last); @@ -377,8 +378,9 @@ struct klist_node *klist_next(struct klist_iter *i) void (*put)(struct klist_node *) = i->i_klist->put; struct klist_node *last = i->i_cur; struct klist_node *next; + unsigned long flags; - spin_lock(&i->i_klist->k_lock); + spin_lock_irqsave(&i->i_klist->k_lock, flags); if (last) { next = to_klist_node(last->n_node.next); @@ -397,7 +399,7 @@ struct klist_node *klist_next(struct klist_iter *i) next = to_klist_node(next->n_node.next); } - spin_unlock(&i->i_klist->k_lock); + spin_unlock_irqrestore(&i->i_klist->k_lock, flags); if (put && last) put(last); |