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, 13 insertions, 34 deletions

diff --git a/drivers/infiniband/hw/qib/qib_rc.c b/drivers/infiniband/hw/qib/qib_rc.c
index 40c0a37..a093111 100644
--- a/drivers/infiniband/hw/qib/qib_rc.c
+++ b/drivers/infiniband/hw/qib/qib_rc.c
@@ -868,7 +868,7 @@ done:
 
 /*
  * Back up requester to resend the last un-ACKed request.
- * The QP s_lock should be held and interrupts disabled.
+ * The QP r_lock and s_lock should be held and interrupts disabled.
  */
 static void qib_restart_rc(struct qib_qp *qp, u32 psn, int wait)
 {
@@ -911,7 +911,8 @@ static void rc_timeout(unsigned long arg)
 	struct qib_ibport *ibp;
 	unsigned long flags;
 
-	spin_lock_irqsave(&qp->s_lock, flags);
+	spin_lock_irqsave(&qp->r_lock, flags);
+	spin_lock(&qp->s_lock);
 	if (qp->s_flags & QIB_S_TIMER) {
 		ibp = to_iport(qp->ibqp.device, qp->port_num);
 		ibp->n_rc_timeouts++;
@@ -920,7 +921,8 @@ static void rc_timeout(unsigned long arg)
 		qib_restart_rc(qp, qp->s_last_psn + 1, 1);
 		qib_schedule_send(qp);
 	}
-	spin_unlock_irqrestore(&qp->s_lock, flags);
+	spin_unlock(&qp->s_lock);
+	spin_unlock_irqrestore(&qp->r_lock, flags);
 }
 
 /*
@@ -1414,10 +1416,6 @@ static void qib_rc_rcv_resp(struct qib_ibport *ibp,
 
 	spin_lock_irqsave(&qp->s_lock, flags);
 
-	/* Double check we can process this now that we hold the s_lock. */
-	if (!(ib_qib_state_ops[qp->state] & QIB_PROCESS_RECV_OK))
-		goto ack_done;
-
 	/* Ignore invalid responses. */
 	if (qib_cmp24(psn, qp->s_next_psn) >= 0)
 		goto ack_done;
@@ -1661,9 +1659,6 @@ static int qib_rc_rcv_error(struct qib_other_headers *ohdr,
 	ibp->n_rc_dupreq++;
 
 	spin_lock_irqsave(&qp->s_lock, flags);
-	/* Double check we can process this now that we hold the s_lock. */
-	if (!(ib_qib_state_ops[qp->state] & QIB_PROCESS_RECV_OK))
-		goto unlock_done;
 
 	for (i = qp->r_head_ack_queue; ; i = prev) {
 		if (i == qp->s_tail_ack_queue)
@@ -1878,9 +1873,6 @@ void qib_rc_rcv(struct qib_ctxtdata *rcd, struct qib_ib_header *hdr,
 	psn = be32_to_cpu(ohdr->bth[2]);
 	opcode >>= 24;
 
-	/* Prevent simultaneous processing after APM on different CPUs */
-	spin_lock(&qp->r_lock);
-
 	/*
 	 * Process responses (ACKs) before anything else.  Note that the
 	 * packet sequence number will be for something in the send work
@@ -1891,14 +1883,14 @@ void qib_rc_rcv(struct qib_ctxtdata *rcd, struct qib_ib_header *hdr,
 	    opcode <= OP(ATOMIC_ACKNOWLEDGE)) {
 		qib_rc_rcv_resp(ibp, ohdr, data, tlen, qp, opcode, psn,
 				hdrsize, pmtu, rcd);
-		goto runlock;
+		return;
 	}
 
 	/* Compute 24 bits worth of difference. */
 	diff = qib_cmp24(psn, qp->r_psn);
 	if (unlikely(diff)) {
 		if (qib_rc_rcv_error(ohdr, data, qp, opcode, psn, diff, rcd))
-			goto runlock;
+			return;
 		goto send_ack;
 	}
 
@@ -2090,9 +2082,6 @@ send_last:
 		if (next > QIB_MAX_RDMA_ATOMIC)
 			next = 0;
 		spin_lock_irqsave(&qp->s_lock, flags);
-		/* Double check we can process this while holding the s_lock. */
-		if (!(ib_qib_state_ops[qp->state] & QIB_PROCESS_RECV_OK))
-			goto srunlock;
 		if (unlikely(next == qp->s_tail_ack_queue)) {
 			if (!qp->s_ack_queue[next].sent)
 				goto nack_inv_unlck;
@@ -2146,7 +2135,7 @@ send_last:
 		qp->s_flags |= QIB_S_RESP_PENDING;
 		qib_schedule_send(qp);
 
-		goto srunlock;
+		goto sunlock;
 	}
 
 	case OP(COMPARE_SWAP):
@@ -2165,9 +2154,6 @@ send_last:
 		if (next > QIB_MAX_RDMA_ATOMIC)
 			next = 0;
 		spin_lock_irqsave(&qp->s_lock, flags);
-		/* Double check we can process this while holding the s_lock. */
-		if (!(ib_qib_state_ops[qp->state] & QIB_PROCESS_RECV_OK))
-			goto srunlock;
 		if (unlikely(next == qp->s_tail_ack_queue)) {
 			if (!qp->s_ack_queue[next].sent)
 				goto nack_inv_unlck;
@@ -2213,7 +2199,7 @@ send_last:
 		qp->s_flags |= QIB_S_RESP_PENDING;
 		qib_schedule_send(qp);
 
-		goto srunlock;
+		goto sunlock;
 	}
 
 	default:
@@ -2227,7 +2213,7 @@ send_last:
 	/* Send an ACK if requested or required. */
 	if (psn & (1 << 31))
 		goto send_ack;
-	goto runlock;
+	return;
 
 rnr_nak:
 	qp->r_nak_state = IB_RNR_NAK | qp->r_min_rnr_timer;
@@ -2238,7 +2224,7 @@ rnr_nak:
 		atomic_inc(&qp->refcount);
 		list_add_tail(&qp->rspwait, &rcd->qp_wait_list);
 	}
-	goto runlock;
+	return;
 
 nack_op_err:
 	qib_rc_error(qp, IB_WC_LOC_QP_OP_ERR);
@@ -2250,7 +2236,7 @@ nack_op_err:
 		atomic_inc(&qp->refcount);
 		list_add_tail(&qp->rspwait, &rcd->qp_wait_list);
 	}
-	goto runlock;
+	return;
 
 nack_inv_unlck:
 	spin_unlock_irqrestore(&qp->s_lock, flags);
@@ -2264,7 +2250,7 @@ nack_inv:
 		atomic_inc(&qp->refcount);
 		list_add_tail(&qp->rspwait, &rcd->qp_wait_list);
 	}
-	goto runlock;
+	return;
 
 nack_acc_unlck:
 	spin_unlock_irqrestore(&qp->s_lock, flags);
@@ -2274,13 +2260,6 @@ nack_acc:
 	qp->r_ack_psn = qp->r_psn;
 send_ack:
 	qib_send_rc_ack(qp);
-runlock:
-	spin_unlock(&qp->r_lock);
-	return;
-
-srunlock:
-	spin_unlock_irqrestore(&qp->s_lock, flags);
-	spin_unlock(&qp->r_lock);
 	return;
 
 sunlock: