netdev - [PATCH 1/2] igb: fix rtnl race in PM resume path

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Date:	Thu,  5 Apr 2012 11:11:03 -0400
From:	Benjamin Poirier <bpoirier@...e.de>
To:	Jeff Kirsher <jeffrey.t.kirsher@...el.com>
Cc:	Alex Duyck <alexander.h.duyck@...el.com>,
	Bruce Allan <bruce.w.allan@...el.com>,
	Carolyn Wyborny <carolyn.wyborny@...el.com>,
	"David S. Miller" <davem@...emloft.net>,
	Don Skidmore <donald.c.skidmore@...el.com>,
	e1000-devel@...ts.sourceforge.net,
	Emil Tantilov <emil.s.tantilov@...el.com>,
	Eric Dumazet <eric.dumazet@...il.com>,
	Greg Rose <gregory.v.rose@...el.com>,
	Jesse Brandeburg <jesse.brandeburg@...el.com>,
	John Fastabend <john.r.fastabend@...el.com>,
	John Ronciak <john.ronciak@...el.com>,
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@...el.com>
Subject: [PATCH 1/2] igb: fix rtnl race in PM resume path

Since the caller (PM resume code) is not the one holding rtnl, when taking the
'else' branch rtnl may be released at any moment, thereby defeating the whole
purpose of this code block.

Signed-off-by: Benjamin Poirier <bpoirier@...e.de>
---
 drivers/net/ethernet/intel/igb/igb_main.c |   20 ++++++--------------
 1 files changed, 6 insertions(+), 14 deletions(-)

diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
index f022ff7..4854ab6 100644
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -1083,9 +1083,12 @@ msi_only:
 		adapter->flags |= IGB_FLAG_HAS_MSI;
 out:
 	/* Notify the stack of the (possibly) reduced queue counts. */
+	rtnl_lock();
 	netif_set_real_num_tx_queues(adapter->netdev, adapter->num_tx_queues);
-	return netif_set_real_num_rx_queues(adapter->netdev,
-					    adapter->num_rx_queues);
+	err = netif_set_real_num_rx_queues(adapter->netdev,
+		adapter->num_rx_queues);
+	rtnl_unlock();
+	return err;
 }
 
 /**
@@ -6646,18 +6649,7 @@ static int igb_resume(struct device *dev)
 	pci_enable_wake(pdev, PCI_D3hot, 0);
 	pci_enable_wake(pdev, PCI_D3cold, 0);
 
-	if (!rtnl_is_locked()) {
-		/*
-		 * shut up ASSERT_RTNL() warning in
-		 * netif_set_real_num_tx/rx_queues.
-		 */
-		rtnl_lock();
-		err = igb_init_interrupt_scheme(adapter);
-		rtnl_unlock();
-	} else {
-		err = igb_init_interrupt_scheme(adapter);
-	}
-	if (err) {
+	if (igb_init_interrupt_scheme(adapter)) {
 		dev_err(&pdev->dev, "Unable to allocate memory for queues\n");
 		return -ENOMEM;
 	}
-- 
1.7.7

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