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authorBart Van Assche <bart.vanassche@wdc.com>2018-06-22 14:54:49 -0700
committerMartin K. Petersen <martin.petersen@oracle.com>2018-07-02 16:20:23 -0400
commit624fa7790f80575a4ec28fbdb2034097dc18d051 (patch)
tree841d959df00321213c77f0faf9548b3cb2457dd8 /lib
parent68c3f904ed4591797ccac22148b95c54af391f30 (diff)
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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>
Diffstat (limited to 'lib')
-rw-r--r--lib/klist.c10
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);