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scsi: core: Ensure that the SCSI error handler gets woken up

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If scsi_eh_scmd_add() is called concurrently with
scsi_host_queue_ready() while shost->host_blocked > 0 then it can
happen that neither function wakes up the SCSI error handler. Fix
this by making every function that decreases the host_busy counter
wake up the error handler if necessary and by protecting the
host_failed checks with the SCSI host lock.

Reported-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
References: https://marc.info/?l=linux-kernel&m=150461610630736
Fixes: commit 7466501608 ("scsi: convert host_busy to atomic_t")
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Tested-by: Stuart Hayes <stuart.w.hayes@gmail.com>
Cc: Konstantin Khorenko <khorenko@virtuozzo.com>
Cc: Stuart Hayes <stuart.w.hayes@gmail.com>
Cc: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Bart Van Assche
2017-12-04 10:06:23 -08:00
committed by Martin K. Petersen
parent 156baec397
commit 3bd6f43f5c
4 changed files with 52 additions and 13 deletions
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6
drivers/scsi/hosts.c
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@@ -318,6 +318,9 @@ static void scsi_host_dev_release(struct device *dev)
scsi_proc_hostdir_rm(shost->hostt);
/* Wait for functions invoked through call_rcu(&shost->rcu, ...) */
rcu_barrier();
if (shost->tmf_work_q)
destroy_workqueue(shost->tmf_work_q);
if (shost->ehandler)
@@ -325,6 +328,8 @@ static void scsi_host_dev_release(struct device *dev)
if (shost->work_q)
destroy_workqueue(shost->work_q);
destroy_rcu_head(&shost->rcu);
if (shost->shost_state == SHOST_CREATED) {
/*
* Free the shost_dev device name here if scsi_host_alloc()
@@ -399,6 +404,7 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
INIT_LIST_HEAD(&shost->starved_list);
init_waitqueue_head(&shost->host_wait);
mutex_init(&shost->scan_mutex);
init_rcu_head(&shost->rcu);
index = ida_simple_get(&host_index_ida, 0, 0, GFP_KERNEL);
if (index < 0)