linux-kernel - [PATCH] pci: Avoid reentrant calls to work_on

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Message-ID: <20130514221748.6180.30597.stgit@ahduyck-cp1.jf.intel.com>
Date:	Tue, 14 May 2013 15:26:53 -0700
From:	Alexander Duyck <alexander.h.duyck@...el.com>
To:	bhelgaas@...gle.com, yinghai@...nel.org
Cc:	guz.fnst@...fujitsu.com, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH] pci: Avoid reentrant calls to work_on_cpu

This change is meant to fix a deadlock seen when pci_enable_sriov was
called from within a driver's probe routine.  The issue was that
work_on_cpu calls flush_work which attempts to flush a work queue for a
cpu that we are currently working in.  In order to avoid the reentrant
path we just skip the call to work_on_cpu in the case that the device
node matches our current node.

Reported-by: Yinghai Lu <yinghai@...nel.org>
Signed-off-by: Alexander Duyck <alexander.h.duyck@...el.com>
---

This patch is meant to address the issue pointed out in an earlier patch
sent by Yinghai Lu titled:
  [PATCH 6/7] PCI: Make sure VF's driver get attached after PF's

 drivers/pci/pci-driver.c |   14 +++++++++-----
 1 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index 79277fb..caeb1c0 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -277,12 +277,16 @@ static int pci_call_probe(struct pci_driver *drv, struct pci_dev *dev,
 	int error, node;
 	struct drv_dev_and_id ddi = { drv, dev, id };
 
-	/* Execute driver initialization on node where the device's
-	   bus is attached to.  This way the driver likely allocates
-	   its local memory on the right node without any need to
-	   change it. */
+	/*
+	 * Execute driver initialization on the node where the device's
+	 * bus is attached.  This way the driver likely allocates
+	 * its local memory on the right node without any need to
+	 * change it.  If the node is the current node just call
+	 * local_pci_probe and avoid the possibility of reentrant
+	 * calls to work_on_cpu.
+	 */
 	node = dev_to_node(&dev->dev);
-	if (node >= 0) {
+	if ((node >= 0) && (node != numa_node_id())) {
 		int cpu;
 
 		get_online_cpus();

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