Avoid that srp_claim_command() can claim a command while
srp_queuecommand() is still busy queueing the same command.
Found this via source reading.

Signed-off-by: Bart Van Assche <[email protected]>
Cc: Roland Dreier <[email protected]>
Cc: David Dillow <[email protected]>
Cc: Vu Pham <[email protected]>
Cc: Sebastian Riemer <[email protected]>
---
 drivers/infiniband/ulp/srp/ib_srp.c |   14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/infiniband/ulp/srp/ib_srp.c 
b/drivers/infiniband/ulp/srp/ib_srp.c
index 368d160..035167b 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -1047,13 +1047,11 @@ map_complete:
 static void srp_put_tx_iu(struct srp_target_port *target, struct srp_iu *iu,
                          enum srp_iu_type iu_type)
 {
-       unsigned long flags;
+       lockdep_assert_held(&target->lock);
 
-       spin_lock_irqsave(&target->lock, flags);
        list_add(&iu->list, &target->free_tx);
        if (iu_type != SRP_IU_RSP)
                ++target->req_lim;
-       spin_unlock_irqrestore(&target->lock, flags);
 }
 
 /*
@@ -1210,7 +1208,10 @@ static int srp_response_common(struct srp_target_port 
*target, s32 req_delta,
        if (err) {
                shost_printk(KERN_ERR, target->scsi_host, PFX
                             "unable to post response: %d\n", err);
+
+               spin_lock_irqsave(&target->lock, flags);
                srp_put_tx_iu(target, iu, SRP_IU_RSP);
+               spin_unlock_irqrestore(&target->lock, flags);
        }
 
        return err;
@@ -1367,7 +1368,6 @@ static int srp_queuecommand(struct Scsi_Host *shost, 
struct scsi_cmnd *scmnd)
 
        req = list_first_entry(&target->free_reqs, struct srp_request, list);
        list_del(&req->list);
-       spin_unlock_irqrestore(&target->lock, flags);
 
        dev = target->srp_host->srp_dev->dev;
        ib_dma_sync_single_for_cpu(dev, iu->dma, target->max_iu_len,
@@ -1401,6 +1401,7 @@ static int srp_queuecommand(struct Scsi_Host *shost, 
struct scsi_cmnd *scmnd)
                shost_printk(KERN_ERR, target->scsi_host, PFX "Send failed\n");
                goto err_unmap;
        }
+       spin_unlock_irqrestore(&target->lock, flags);
 
        return 0;
 
@@ -1409,8 +1410,6 @@ err_unmap:
 
 err_iu:
        srp_put_tx_iu(target, iu, SRP_IU_CMD);
-
-       spin_lock_irqsave(&target->lock, flags);
        list_add(&req->list, &target->free_reqs);
 
 err_unlock:
@@ -1729,7 +1728,10 @@ static int srp_send_tsk_mgmt(struct srp_target_port 
*target,
        ib_dma_sync_single_for_device(dev, iu->dma, sizeof *tsk_mgmt,
                                      DMA_TO_DEVICE);
        if (srp_post_send(target, iu, sizeof *tsk_mgmt)) {
+               spin_lock_irq(&target->lock);
                srp_put_tx_iu(target, iu, SRP_IU_TSK_MGMT);
+               spin_unlock_irq(&target->lock);
+
                return -1;
        }
 
-- 
1.7.10.4

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