3.16.62-rc1 review patch. If anyone has any objections, please let me know.
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From: Steve Wise swise@opengridcomputing.com
commit bc52e9ca74b9a395897bb640c6671b2cbf716032 upstream.
__flush_qp() has a race condition where during the flush operation, the qp lock is released allowing another thread to possibly post a WR, which corrupts the queue state, possibly causing crashes. The lock was released to preserve the cq/qp locking hierarchy of cq first, then qp. However releasing the qp lock is not necessary; both RQ and SQ CQ locks can be acquired first, followed by the qp lock, and then the RQ and SQ flushing can be done w/o unlocking.
Signed-off-by: Steve Wise swise@opengridcomputing.com Signed-off-by: Doug Ledford dledford@redhat.com [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/infiniband/hw/cxgb4/qp.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-)
--- a/drivers/infiniband/hw/cxgb4/qp.c +++ b/drivers/infiniband/hw/cxgb4/qp.c @@ -1071,31 +1071,34 @@ static void __flush_qp(struct c4iw_qp *q
PDBG("%s qhp %p rchp %p schp %p\n", __func__, qhp, rchp, schp);
- /* locking hierarchy: cq lock first, then qp lock. */ + /* locking hierarchy: cqs lock first, then qp lock. */ spin_lock_irqsave(&rchp->lock, flag); + if (schp != rchp) + spin_lock(&schp->lock); spin_lock(&qhp->lock);
if (qhp->wq.flushed) { spin_unlock(&qhp->lock); + if (schp != rchp) + spin_unlock(&schp->lock); spin_unlock_irqrestore(&rchp->lock, flag); return; } qhp->wq.flushed = 1; + t4_set_wq_in_error(&qhp->wq);
c4iw_flush_hw_cq(rchp, qhp); c4iw_count_rcqes(&rchp->cq, &qhp->wq, &count); rq_flushed = c4iw_flush_rq(&qhp->wq, &rchp->cq, count); - spin_unlock(&qhp->lock); - spin_unlock_irqrestore(&rchp->lock, flag);
- /* locking hierarchy: cq lock first, then qp lock. */ - spin_lock_irqsave(&schp->lock, flag); - spin_lock(&qhp->lock); if (schp != rchp) c4iw_flush_hw_cq(schp, qhp); sq_flushed = c4iw_flush_sq(qhp); + spin_unlock(&qhp->lock); - spin_unlock_irqrestore(&schp->lock, flag); + if (schp != rchp) + spin_unlock(&schp->lock); + spin_unlock_irqrestore(&rchp->lock, flag);
if (schp == rchp) { if (t4_clear_cq_armed(&rchp->cq) && @@ -1129,8 +1132,8 @@ static void flush_qp(struct c4iw_qp *qhp rchp = to_c4iw_cq(qhp->ibqp.recv_cq); schp = to_c4iw_cq(qhp->ibqp.send_cq);
- t4_set_wq_in_error(&qhp->wq); 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);