IB/qib: Fix race between qib_error_qp() and receive packet processing

When transitioning a QP to the error state, in progress RWQEs need to
be marked complete.  This also involves releasing the reference count
to the memory regions referenced in the SGEs.  The locking in the
receive packet processing wasn't sufficient to prevent qib_error_qp()
from modifying the r_sge state at the same time, thus leading to
kernel panics.

Signed-off-by: Ralph Campbell <ralph.campbell@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 4 insertions, 13 deletions

diff --git a/drivers/infiniband/hw/qib/qib_ud.c b/drivers/infiniband/hw/qib/qib_ud.c
index c838cda73347..e1b3da2a1f85 100644
--- a/drivers/infiniband/hw/qib/qib_ud.c
+++ b/drivers/infiniband/hw/qib/qib_ud.c
@@ -535,13 +535,6 @@ void qib_ud_rcv(struct qib_ibport *ibp, struct qib_ib_header *hdr,
 	wc.byte_len = tlen + sizeof(struct ib_grh);
 
 	/*
-	 * We need to serialize getting a receive work queue entry and
-	 * generating a completion for it against QPs sending to this QP
-	 * locally.
-	 */
-	spin_lock(&qp->r_lock);
-
-	/*
 	 * Get the next work request entry to find where to put the data.
 	 */
 	if (qp->r_flags & QIB_R_REUSE_SGE)
@@ -552,19 +545,19 @@ void qib_ud_rcv(struct qib_ibport *ibp, struct qib_ib_header *hdr,
 		ret = qib_get_rwqe(qp, 0);
 		if (ret < 0) {
 			qib_rc_error(qp, IB_WC_LOC_QP_OP_ERR);
-			goto bail_unlock;
+			return;
 		}
 		if (!ret) {
 			if (qp->ibqp.qp_num == 0)
 				ibp->n_vl15_dropped++;
-			goto bail_unlock;
+			return;
 		}
 	}
 	/* Silently drop packets which are too big. */
 	if (unlikely(wc.byte_len > qp->r_len)) {
 		qp->r_flags |= QIB_R_REUSE_SGE;
 		ibp->n_pkt_drops++;
-		goto bail_unlock;
+		return;
 	}
 	if (has_grh) {
 		qib_copy_sge(&qp->r_sge, &hdr->u.l.grh,
@@ -579,7 +572,7 @@ void qib_ud_rcv(struct qib_ibport *ibp, struct qib_ib_header *hdr,
 			qp->r_sge.sge = *qp->r_sge.sg_list++;
 	}
 	if (!test_and_clear_bit(QIB_R_WRID_VALID, &qp->r_aflags))
-		goto bail_unlock;
+		return;
 	wc.wr_id = qp->r_wr_id;
 	wc.status = IB_WC_SUCCESS;
 	wc.opcode = IB_WC_RECV;
@@ -601,7 +594,5 @@ void qib_ud_rcv(struct qib_ibport *ibp, struct qib_ib_header *hdr,
 	qib_cq_enter(to_icq(qp->ibqp.recv_cq), &wc,
 		     (ohdr->bth[0] &
 			cpu_to_be32(IB_BTH_SOLICITED)) != 0);
-bail_unlock:
-	spin_unlock(&qp->r_lock);
 bail:;
 }