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Subject[PATCH 4.0 43/58] scsi_transport_srp: Introduce srp_wait_for_queuecommand()
Date
4.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Bart Van Assche <bart.vanassche@sandisk.com>

commit be34c62ddf39d1931780b07a6f4241393e4ba2ee upstream.

Introduce the helper function srp_wait_for_queuecommand().
Move the definition of scsi_request_fn_active(). Add a comment
above srp_wait_for_queuecommand() that support for scsi-mq needs
to be added.

This patch does not change any functionality. A second call to
srp_wait_for_queuecommand() will be introduced in the next patch.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: James Bottomley <JBottomley@Odin.com>
Cc: Sagi Grimberg <sagig@mellanox.com>
Cc: Sebastian Parschauer <sebastian.riemer@profitbricks.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/scsi/scsi_transport_srp.c | 54 +++++++++++++++++++++-----------------
1 file changed, 31 insertions(+), 23 deletions(-)

--- a/drivers/scsi/scsi_transport_srp.c
+++ b/drivers/scsi/scsi_transport_srp.c
@@ -396,6 +396,36 @@ static void srp_reconnect_work(struct wo
}
}

+/**
+ * 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);
@@ -504,27 +534,6 @@ void srp_start_tl_fail_timers(struct srp
EXPORT_SYMBOL(srp_start_tl_fail_timers);

/**
- * 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.
- */
-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;
-}
-
-/**
* srp_reconnect_rport() - reconnect to an SRP target port
* @rport: SRP target port.
*
@@ -559,8 +568,7 @@ int srp_reconnect_rport(struct srp_rport
if (res)
goto out;
scsi_target_block(&shost->shost_gendev);
- while (scsi_request_fn_active(shost))
- msleep(20);
+ srp_wait_for_queuecommand(shost);
res = rport->state != SRP_RPORT_LOST ? i->f->reconnect(rport) : -ENODEV;
pr_debug("%s (state %d): transport.reconnect() returned %d\n",
dev_name(&shost->shost_gendev), rport->state, res);



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