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RDMA/cxgb4: Serialize calls to CQ's comp_handler

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Commit 01e7da6ba5 ("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>
This commit is contained in:
Kumar Sanghvi
2011-10-24 21:20:21 +05:30
committed by Roland Dreier
parent e14d62c05c
commit 581bbe2cd0
4 changed files with 23 additions and 4 deletions
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10
drivers/infiniband/hw/cxgb4/ev.c
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@@ -42,6 +42,7 @@ static void post_qp_event(struct c4iw_dev *dev, struct c4iw_cq *chp,
{
struct ib_event event;
struct c4iw_qp_attributes attrs;
unsigned long flag;
if ((qhp->attr.state == C4IW_QP_STATE_ERROR) ||
(qhp->attr.state == C4IW_QP_STATE_TERMINATE)) {
@@ -72,7 +73,9 @@ static void post_qp_event(struct c4iw_dev *dev, struct c4iw_cq *chp,
if (qhp->ibqp.event_handler)
(*qhp->ibqp.event_handler)(&event, qhp->ibqp.qp_context);
spin_lock_irqsave(&chp->comp_handler_lock, flag);
(*chp->ibcq.comp_handler)(&chp->ibcq, chp->ibcq.cq_context);
spin_unlock_irqrestore(&chp->comp_handler_lock, flag);
}
void c4iw_ev_dispatch(struct c4iw_dev *dev, struct t4_cqe *err_cqe)
@@ -183,11 +186,14 @@ out:
int c4iw_ev_handler(struct c4iw_dev *dev, u32 qid)
{
struct c4iw_cq *chp;
unsigned long flag;
chp = get_chp(dev, qid);
if (chp)
if (chp) {
spin_lock_irqsave(&chp->comp_handler_lock, flag);
(*chp->ibcq.comp_handler)(&chp->ibcq, chp->ibcq.cq_context);
else
spin_unlock_irqrestore(&chp->comp_handler_lock, flag);
} else
PDBG("%s unknown cqid 0x%x\n", __func__, qid);
return 0;
}