linux-kernel - [PATCH 4.10 38/63] amd-xgbe: Enable IRQs only if napi_complete

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Message-Id: <20170320174745.485991404@linuxfoundation.org>
Date:   Mon, 20 Mar 2017 18:52:03 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jeremy Linton <jeremy.linton@....com>,
        Tom Lendacky <thomas.lendacky@....com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.10 38/63] amd-xgbe: Enable IRQs only if napi_complete_done() is true

4.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: "Lendacky, Thomas" <Thomas.Lendacky@....com>


[ Upstream commit d7aba644ffdebf756e51e26a2229055211838e89 ]

Depending on the hardware, the amd-xgbe driver may use disable_irq_nosync()
and enable_irq() when an interrupt is received to process Rx packets. If
the napi_complete_done() return value isn't checked an unbalanced enable
for the IRQ could result, generating a warning stack trace.

Update the driver to only enable interrupts if napi_complete_done() returns
true.

Reported-by: Jeremy Linton <jeremy.linton@....com>
Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/net/ethernet/amd/xgbe/xgbe-drv.c |   10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

--- a/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
+++ b/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
@@ -2274,10 +2274,7 @@ static int xgbe_one_poll(struct napi_str
 	processed = xgbe_rx_poll(channel, budget);
 
 	/* If we processed everything, we are done */
-	if (processed < budget) {
-		/* Turn off polling */
-		napi_complete_done(napi, processed);
-
+	if ((processed < budget) && napi_complete_done(napi, processed)) {
 		/* Enable Tx and Rx interrupts */
 		if (pdata->channel_irq_mode)
 			xgbe_enable_rx_tx_int(pdata, channel);
@@ -2319,10 +2316,7 @@ static int xgbe_all_poll(struct napi_str
 	} while ((processed < budget) && (processed != last_processed));
 
 	/* If we processed everything, we are done */
-	if (processed < budget) {
-		/* Turn off polling */
-		napi_complete_done(napi, processed);
-
+	if ((processed < budget) && napi_complete_done(napi, processed)) {
 		/* Enable Tx and Rx interrupts */
 		xgbe_enable_rx_tx_ints(pdata);
 	}