From 3bd6f43f5cb3714f70c591514f344389df593501 Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Mon, 4 Dec 2017 10:06:23 -0800 Subject: scsi: core: Ensure that the SCSI error handler gets woken up 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 References: https://marc.info/?l=linux-kernel&m=150461610630736 Fixes: commit 746650160866 ("scsi: convert host_busy to atomic_t") Signed-off-by: Bart Van Assche Reviewed-by: Pavel Tikhomirov Tested-by: Stuart Hayes Cc: Konstantin Khorenko Cc: Stuart Hayes Cc: Pavel Tikhomirov Cc: Christoph Hellwig Cc: Hannes Reinecke Cc: Johannes Thumshirn Cc: Signed-off-by: Martin K. Petersen --- drivers/scsi/scsi_lib.c | 39 ++++++++++++++++++++++++++++----------- 1 file changed, 28 insertions(+), 11 deletions(-) (limited to 'drivers/scsi/scsi_lib.c') diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 1cbc497e00bd..1827956b33c9 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -318,22 +318,39 @@ static void scsi_init_cmd_errh(struct scsi_cmnd *cmd) cmd->cmd_len = scsi_command_size(cmd->cmnd); } -void scsi_device_unbusy(struct scsi_device *sdev) +/* + * Decrement the host_busy counter and wake up the error handler if necessary. + * Avoid as follows that the error handler is not woken up if shost->host_busy + * == shost->host_failed: use call_rcu() in scsi_eh_scmd_add() in combination + * with an RCU read lock in this function to ensure that this function in its + * entirety either finishes before scsi_eh_scmd_add() increases the + * host_failed counter or that it notices the shost state change made by + * scsi_eh_scmd_add(). + */ +static void scsi_dec_host_busy(struct Scsi_Host *shost) { - struct Scsi_Host *shost = sdev->host; - struct scsi_target *starget = scsi_target(sdev); unsigned long flags; + rcu_read_lock(); atomic_dec(&shost->host_busy); - if (starget->can_queue > 0) - atomic_dec(&starget->target_busy); - - if (unlikely(scsi_host_in_recovery(shost) && - (shost->host_failed || shost->host_eh_scheduled))) { + if (unlikely(scsi_host_in_recovery(shost))) { spin_lock_irqsave(shost->host_lock, flags); - scsi_eh_wakeup(shost); + if (shost->host_failed || shost->host_eh_scheduled) + scsi_eh_wakeup(shost); spin_unlock_irqrestore(shost->host_lock, flags); } + rcu_read_unlock(); +} + +void scsi_device_unbusy(struct scsi_device *sdev) +{ + struct Scsi_Host *shost = sdev->host; + struct scsi_target *starget = scsi_target(sdev); + + scsi_dec_host_busy(shost); + + if (starget->can_queue > 0) + atomic_dec(&starget->target_busy); atomic_dec(&sdev->device_busy); } @@ -1532,7 +1549,7 @@ starved: list_add_tail(&sdev->starved_entry, &shost->starved_list); spin_unlock_irq(shost->host_lock); out_dec: - atomic_dec(&shost->host_busy); + scsi_dec_host_busy(shost); return 0; } @@ -2018,7 +2035,7 @@ static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx, return BLK_STS_OK; out_dec_host_busy: - atomic_dec(&shost->host_busy); + scsi_dec_host_busy(shost); out_dec_target_busy: if (scsi_target(sdev)->can_queue > 0) atomic_dec(&scsi_target(sdev)->target_busy); -- cgit v1.2.3 From e4c9470b9f21a0ee3b4625f6d29792c240b71c67 Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Thu, 7 Dec 2017 15:59:31 -0800 Subject: scsi: core: Unexport scsi_initialize_rq() Commit 651a01364994 ("scsi: scsi_transport_sas: switch to bsg-lib for SMP passthrough") removed the only call to scsi_initialize_rq() from outside the SCSI core. Hence unexport scsi_initialize_rq(). Signed-off-by: Bart Van Assche Cc: Christoph Hellwig Cc: Hannes Reinecke Cc: Johannes Thumshirn Signed-off-by: Martin K. Petersen --- drivers/scsi/scsi_lib.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'drivers/scsi/scsi_lib.c') diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 1827956b33c9..c3fc4353af3c 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -1145,7 +1145,7 @@ EXPORT_SYMBOL(scsi_init_io); * Called from inside blk_get_request() for pass-through requests and from * inside scsi_init_command() for filesystem requests. */ -void scsi_initialize_rq(struct request *rq) +static void scsi_initialize_rq(struct request *rq) { struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq); @@ -1153,7 +1153,6 @@ void scsi_initialize_rq(struct request *rq) cmd->jiffies_at_alloc = jiffies; cmd->retries = 0; } -EXPORT_SYMBOL(scsi_initialize_rq); /* Add a command to the list used by the aacraid and dpt_i2o drivers */ void scsi_add_cmd_to_list(struct scsi_cmnd *cmd) -- cgit v1.2.3 From 08640e81dc33e02405b909bb289fcf91de663443 Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Wed, 10 Jan 2018 14:41:45 -0800 Subject: scsi: core: Change third __scsi_queue_insert() argument from int to bool This patch does not change any functionality but makes the SCSI core source code slightly easier to read. Signed-off-by: Bart Van Assche Cc: Christoph Hellwig Cc: Hannes Reinecke Cc: Johannes Thumshirn Signed-off-by: Martin K. Petersen --- drivers/scsi/scsi_lib.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'drivers/scsi/scsi_lib.c') diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index c3fc4353af3c..5cbc69b2b1ae 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -164,7 +164,7 @@ static void scsi_mq_requeue_cmd(struct scsi_cmnd *cmd) * for a requeue after completion, which should only occur in this * file. */ -static void __scsi_queue_insert(struct scsi_cmnd *cmd, int reason, int unbusy) +static void __scsi_queue_insert(struct scsi_cmnd *cmd, int reason, bool unbusy) { struct scsi_device *device = cmd->device; struct request_queue *q = device->request_queue; @@ -220,7 +220,7 @@ static void __scsi_queue_insert(struct scsi_cmnd *cmd, int reason, int unbusy) */ void scsi_queue_insert(struct scsi_cmnd *cmd, int reason) { - __scsi_queue_insert(cmd, reason, 1); + __scsi_queue_insert(cmd, reason, true); } @@ -1015,11 +1015,11 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes) break; case ACTION_RETRY: /* Retry the same command immediately */ - __scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY, 0); + __scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY, false); break; case ACTION_DELAYED_RETRY: /* Retry the same command after a delay */ - __scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY, 0); + __scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY, false); break; } } -- cgit v1.2.3