RDMA/cxgb4: Serialize calls to CQ's comp_handler
Commit 01e7da6ba53c ("RDMA/cxgb4: Make sure flush CQ entries are
collected on connection close") introduced a potential problem where a
CQ's comp_handler can get called simultaneously from different places
in the iw_cxgb4 driver. This does not comply with
Documentation/infiniband/core_locking.txt, which states that at a
given point of time, there should be only one callback per CQ should
be active.
This problem was reported by Parav Pandit <Parav.Pandit@Emulex.Com>.
Based on discussion between Parav Pandit and Steve Wise, this patch
fixes the above problem by serializing the calls to a CQ's
comp_handler using a spin_lock.
Reported-by: Parav Pandit <Parav.Pandit@Emulex.Com>
Signed-off-by: Kumar Sanghvi <kumaras@chelsio.com>
Acked-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
diff --git a/drivers/infiniband/hw/cxgb4/qp.c b/drivers/infiniband/hw/cxgb4/qp.c
index 892fa7c..62c7262 100644
--- a/drivers/infiniband/hw/cxgb4/qp.c
+++ b/drivers/infiniband/hw/cxgb4/qp.c
@@ -941,8 +941,11 @@
flushed = c4iw_flush_rq(&qhp->wq, &rchp->cq, count);
spin_unlock(&qhp->lock);
spin_unlock_irqrestore(&rchp->lock, flag);
- if (flushed)
+ if (flushed) {
+ spin_lock_irqsave(&rchp->comp_handler_lock, flag);
(*rchp->ibcq.comp_handler)(&rchp->ibcq, rchp->ibcq.cq_context);
+ spin_unlock_irqrestore(&rchp->comp_handler_lock, flag);
+ }
/* locking hierarchy: cq lock first, then qp lock. */
spin_lock_irqsave(&schp->lock, flag);
@@ -952,13 +955,17 @@
flushed = c4iw_flush_sq(&qhp->wq, &schp->cq, count);
spin_unlock(&qhp->lock);
spin_unlock_irqrestore(&schp->lock, flag);
- if (flushed)
+ if (flushed) {
+ spin_lock_irqsave(&schp->comp_handler_lock, flag);
(*schp->ibcq.comp_handler)(&schp->ibcq, schp->ibcq.cq_context);
+ spin_unlock_irqrestore(&schp->comp_handler_lock, flag);
+ }
}
static void flush_qp(struct c4iw_qp *qhp)
{
struct c4iw_cq *rchp, *schp;
+ unsigned long flag;
rchp = get_chp(qhp->rhp, qhp->attr.rcq);
schp = get_chp(qhp->rhp, qhp->attr.scq);
@@ -966,11 +973,15 @@
if (qhp->ibqp.uobject) {
t4_set_wq_in_error(&qhp->wq);
t4_set_cq_in_error(&rchp->cq);
+ spin_lock_irqsave(&rchp->comp_handler_lock, flag);
(*rchp->ibcq.comp_handler)(&rchp->ibcq, rchp->ibcq.cq_context);
+ spin_unlock_irqrestore(&rchp->comp_handler_lock, flag);
if (schp != rchp) {
t4_set_cq_in_error(&schp->cq);
+ spin_lock_irqsave(&schp->comp_handler_lock, flag);
(*schp->ibcq.comp_handler)(&schp->ibcq,
schp->ibcq.cq_context);
+ spin_unlock_irqrestore(&schp->comp_handler_lock, flag);
}
return;
}