Merge remote-tracking branch 'torvalds/master' into perf/core

To pick up fixes that went thru perf/urgent.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 24 insertions, 1 deletions

diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index 98498a76ae16..d13f06cf0308 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -1573,7 +1573,14 @@ static int macb_poll(struct napi_struct *napi, int budget)
 	if (work_done < budget) {
 		napi_complete_done(napi, work_done);
 
-		/* Packets received while interrupts were disabled */
+		/* RSR bits only seem to propagate to raise interrupts when
+		 * interrupts are enabled at the time, so if bits are already
+		 * set due to packets received while interrupts were disabled,
+		 * they will not cause another interrupt to be generated when
+		 * interrupts are re-enabled.
+		 * Check for this case here. This has been seen to happen
+		 * around 30% of the time under heavy network load.
+		 */
 		status = macb_readl(bp, RSR);
 		if (status) {
 			if (bp->caps & MACB_CAPS_ISR_CLEAR_ON_WRITE)
@@ -1581,6 +1588,22 @@ static int macb_poll(struct napi_struct *napi, int budget)
 			napi_reschedule(napi);
 		} else {
 			queue_writel(queue, IER, bp->rx_intr_mask);
+
+			/* In rare cases, packets could have been received in
+			 * the window between the check above and re-enabling
+			 * interrupts. Therefore, a double-check is required
+			 * to avoid losing a wakeup. This can potentially race
+			 * with the interrupt handler doing the same actions
+			 * if an interrupt is raised just after enabling them,
+			 * but this should be harmless.
+			 */
+			status = macb_readl(bp, RSR);
+			if (unlikely(status)) {
+				queue_writel(queue, IDR, bp->rx_intr_mask);
+				if (bp->caps & MACB_CAPS_ISR_CLEAR_ON_WRITE)
+					queue_writel(queue, ISR, MACB_BIT(RCOMP));
+				napi_schedule(napi);
+			}
 		}
 	}