netdev - [PATCH net RFC 2/2] ixgbe: fix sleep bug caused by napi_disable inside local_bh

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Message-ID: <20130918202016.8697.56423.stgit@jekeller-desk1.amr.corp.intel.com>
Date:	Wed, 18 Sep 2013 13:20:31 -0700
From:	Jacob Keller <jacob.e.keller@...el.com>
To:	netdev@...r.kernel.org
Cc:	Alexander Duyck <alexander.duyck@...el.com>,
	Hyong-Youb Kim <hykim@...i.com>,
	Dmitry Kravkov <dmitry@...adcom.com>,
	Amir Vadai <amirv@...lanox.com>,
	Eliezer Tamir <eliezer.tamir@...ux.intel.com>
Subject: [PATCH net RFC 2/2] ixgbe: fix sleep bug caused by napi_disable
 inside local_bh_disable()d context

This patch fixes a bug caused by calling napi_disable after local_bh_disable.
It is possible for napi_disable to sleep, (though not guarunteed) so it could
cause an atomic sleep bug during the  schedule() call in msleep. This patch
resolves the issue by moving the local_bh_disable() calls inside the for loop
in ixgbe_napi_disable_all().

Signed-off-by: Jacob Keller <jacob.e.keller@...el.com>
Cc: Eliezer Tamir <eliezer.tamir@...ux.intel.com>
Cc: Alexander Duyck <alexander.duyck@...el.com>
Cc: Hyong-Youb Kim <hykim@...i.com>
Cc: Amir Vadai <amirv@...lanox.com>
Cc: Dmitry Kravkov <dmitry@...adcom.com>
---
 drivers/net/ethernet/intel/ixgbe/ixgbe_main.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index 0ade0cd..85dbf58 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -3893,15 +3893,15 @@ static void ixgbe_napi_disable_all(struct ixgbe_adapter *adapter)
 {
 	int q_idx;
 
-	local_bh_disable(); /* for ixgbe_qv_lock_napi() */
 	for (q_idx = 0; q_idx < adapter->num_q_vectors; q_idx++) {
 		napi_disable(&adapter->q_vector[q_idx]->napi);
+		local_bh_disable(); /* for ixgbe_qv_lock_napi() */
 		while (!ixgbe_qv_lock_napi(adapter->q_vector[q_idx])) {
 			pr_info("QV %d locked\n", q_idx);
 			mdelay(1);
 		}
+		local_bh_enable();
 	}
-	local_bh_enable();
 }
 
 #ifdef CONFIG_IXGBE_DCB

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