Re: [PATCH v5 11/14] SRP transport: Move queuecommand() wait code to SCSI core

[Martin K. Petersen]

> "Bart" == Bart Van Assche  writes:

Bart> Additionally, rename srp_wait_for_queuecommand() into
Bart> scsi_wait_for_queuecommand() and add a comment about the
Bart> queuecommand() call from scsi_send_eh_cmnd().

Reviewed-by: Martin K. Petersen 

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Martin K. Petersen  Oracle Linux Engineering
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Re: [PATCH v5 11/14] SRP transport: Move queuecommand() wait code to SCSI core

[Sagi Grimberg]

Again,

Reviewed-by: Sagi Grimberg 
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[PATCH v5 11/14] SRP transport: Move queuecommand() wait code to SCSI core

[Bart Van Assche]

Additionally, rename srp_wait_for_queuecommand() into
scsi_wait_for_queuecommand() and add a comment about the
queuecommand() call from scsi_send_eh_cmnd().

Signed-off-by: Bart Van Assche 
Cc: James Bottomley 
Cc: Martin K. Petersen 
Cc: Christoph Hellwig 
Cc: Sagi Grimberg 
Cc: Doug Ledford 
---
 drivers/scsi/scsi_lib.c   | 38 
 drivers/scsi/scsi_transport_srp.c | 41 ++-
 2 files changed, 44 insertions(+), 35 deletions(-)

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index b4f682c..3ab9c87 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -2721,6 +2721,39 @@ void sdev_evt_send_simple(struct scsi_device *sdev,
 EXPORT_SYMBOL_GPL(sdev_evt_send_simple);
 
 /**
+ * scsi_request_fn_active() - number of kernel threads inside scsi_request_fn()
+ * @sdev: SCSI device to count the number of scsi_request_fn() callers for.
+ */
+static int scsi_request_fn_active(struct scsi_device *sdev)
+{
+   struct request_queue *q = sdev->request_queue;
+   int request_fn_active;
+
+   WARN_ON_ONCE(sdev->host->use_blk_mq);
+
+   spin_lock_irq(q->queue_lock);
+   request_fn_active = q->request_fn_active;
+   spin_unlock_irq(q->queue_lock);
+
+   return request_fn_active;
+}
+
+/**
+ * scsi_wait_for_queuecommand() - wait for ongoing queuecommand() calls
+ * @shost: SCSI host pointer.
+ *
+ * Wait until the ongoing shost->hostt->queuecommand() calls that are
+ * invoked from scsi_request_fn() have finished.
+ */
+static void scsi_wait_for_queuecommand(struct scsi_device *sdev)
+{
+   WARN_ON_ONCE(sdev->host->use_blk_mq);
+
+   while (scsi_request_fn_active(sdev))
+   msleep(20);
+}
+
+/**
  * scsi_device_quiesce - Block user issued commands.
  * @sdev:  scsi device to quiesce.
  *
@@ -2814,6 +2847,10 @@ EXPORT_SYMBOL(scsi_target_resume);
  * (which must be a legal transition).  When the device is in this
  * state, all commands are deferred until the scsi lld reenables
  * the device with scsi_device_unblock or device_block_tmo fires.
+ *
+ * To do: avoid that scsi_send_eh_cmnd() calls queuecommand() after
+ * scsi_internal_device_block() has blocked a SCSI device and also
+ * remove the rport mutex lock and unlock calls from srp_queuecommand().
  */
 int
 scsi_internal_device_block(struct scsi_device *sdev)
@@ -2841,6 +2878,7 @@ scsi_internal_device_block(struct scsi_device *sdev)
spin_lock_irqsave(q->queue_lock, flags);
blk_stop_queue(q);
spin_unlock_irqrestore(q->queue_lock, flags);
+   scsi_wait_for_queuecommand(sdev);
}
 
return 0;
diff --git a/drivers/scsi/scsi_transport_srp.c 
b/drivers/scsi/scsi_transport_srp.c
index e3cd3ec..b48328a 100644
--- a/drivers/scsi/scsi_transport_srp.c
+++ b/drivers/scsi/scsi_transport_srp.c
@@ -24,7 +24,6 @@
 #include 
 #include 
 #include 
-#include 
 
 #include 
 #include 
@@ -402,36 +401,6 @@ static void srp_reconnect_work(struct work_struct *work)
}
 }
 
-/**
- * scsi_request_fn_active() - number of kernel threads inside scsi_request_fn()
- * @shost: SCSI host for which to count the number of scsi_request_fn() 
callers.
- *
- * To do: add support for scsi-mq in this function.
- */
-static int scsi_request_fn_active(struct Scsi_Host *shost)
-{
-   struct scsi_device *sdev;
-   struct request_queue *q;
-   int request_fn_active = 0;
-
-   shost_for_each_device(sdev, shost) {
-   q = sdev->request_queue;
-
-   spin_lock_irq(q->queue_lock);
-   request_fn_active += q->request_fn_active;
-   spin_unlock_irq(q->queue_lock);
-   }
-
-   return request_fn_active;
-}
-
-/* Wait until ongoing shost->hostt->queuecommand() calls have finished. */
-static void srp_wait_for_queuecommand(struct Scsi_Host *shost)
-{
-   while (scsi_request_fn_active(shost))
-   msleep(20);
-}
-
 static void __rport_fail_io_fast(struct srp_rport *rport)
 {
struct Scsi_Host *shost = rport_to_shost(rport);
@@ -441,14 +410,17 @@ static void __rport_fail_io_fast(struct srp_rport *rport)
 
if (srp_rport_set_state(rport, SRP_RPORT_FAIL_FAST))
return;
+   /*
+* Call scsi_target_block() to wait for ongoing shost->queuecommand()
+* calls before invoking i->f->terminate_rport_io().
+*/
+   scsi_target_block(rport->dev.parent);
scsi_target_unblock(rport->dev.parent, SDEV_TRANSPORT_OFFLINE);
 
/* Involve the LLD if possible to terminate all I/O on the rport. */
i = to_srp_internal(shost->transportt);
-   if (i->f->terminate_rport_io) {
-   srp_wait_for_queuecommand(shost);
+   if (i->f->terminate_rport_io)