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RDMA/cxgb4: Serialize calls to CQ's comp_handler 

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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
drivers/infiniband/hw/cxgb4/cq.c
View File

@ -818,6 +818,7 @@ struct ib_cq *c4iw_create_cq(struct ib_device *ibdev, int entries,
chp->cq.size--; /* status page */
chp->ibcq.cqe = entries - 2;
spin_lock_init(&chp->lock);
spin_lock_init(&chp->comp_handler_lock);
atomic_set(&chp->refcnt, 1);
init_waitqueue_head(&chp->wait);
ret = insert_handle(rhp, &rhp->cqidr, chp, chp->cq.cqid);

10
drivers/infiniband/hw/cxgb4/ev.c
View File

@ -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;
}

1
drivers/infiniband/hw/cxgb4/iw_cxgb4.h
View File

@ -309,6 +309,7 @@ struct c4iw_cq {
struct c4iw_dev *rhp;
struct t4_cq cq;
spinlock_t lock;
spinlock_t comp_handler_lock;
atomic_t refcnt;
wait_queue_head_t wait;
};

15
drivers/infiniband/hw/cxgb4/qp.c
View File

@ -941,8 +941,11 @@ static void __flush_qp(struct c4iw_qp *qhp, struct c4iw_cq *rchp,
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 @@ static void __flush_qp(struct c4iw_qp *qhp, struct c4iw_cq *rchp,
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 @@ static void flush_qp(struct c4iw_qp *qhp)
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;
}