From aa7374ac19ca08715693b0a2d9f88f479af3ea7c Mon Sep 17 00:00:00 2001
From: Mike Marciniszyn <mike.marciniszyn@qlogic.com>
Date: Mon, 10 Jan 2011 17:42:21 -0800
Subject: IB/qib: Avoid duplicate writes to the rcv head register

Avoid duplicate writes to the head register as this can lead to lost
interrupts if the context goes full before the second write is done.

Signed-off-by: Mike Marciniszyn <mike.marciniszyn@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

diff --git a/drivers/infiniband/hw/qib/qib_driver.c b/drivers/infiniband/hw/qib/qib_driver.c
index 9cd1936..3ed0d5a 100644
--- a/drivers/infiniband/hw/qib/qib_driver.c
+++ b/drivers/infiniband/hw/qib/qib_driver.c
@@ -71,6 +71,11 @@ MODULE_DESCRIPTION("QLogic IB driver");
  */
 #define QIB_PIO_MAXIBHDR 128
 
+/*
+ * QIB_MAX_PKT_RCV is the max # if packets processed per receive interrupt.
+ */
+#define QIB_MAX_PKT_RECV 64
+
 struct qlogic_ib_stats qib_stats;
 
 const char *qib_get_unit_name(int unit)
@@ -335,7 +340,7 @@ u32 qib_kreceive(struct qib_ctxtdata *rcd, u32 *llic, u32 *npkts)
 		smp_rmb();  /* prevent speculative reads of dma'ed hdrq */
 	}
 
-	for (last = 0, i = 1; !last && i <= 64; i += !last) {
+	for (last = 0, i = 1; !last; i += !last) {
 		hdr = dd->f_get_msgheader(dd, rhf_addr);
 		eflags = qib_hdrget_err_flags(rhf_addr);
 		etype = qib_hdrget_rcv_type(rhf_addr);
@@ -384,6 +389,9 @@ move_along:
 		l += rsize;
 		if (l >= maxcnt)
 			l = 0;
+		if (i == QIB_MAX_PKT_RECV)
+			last = 1;
+
 		rhf_addr = (__le32 *) rcd->rcvhdrq + l + dd->rhf_offset;
 		if (dd->flags & QIB_NODMA_RTAIL) {
 			u32 seq = qib_hdrget_seq(rhf_addr);
-- 
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