Re: [PATCH] pci: Avoid reentrant calls to work_on_cpu

From: Or Gerlitz
Date: Tue May 14 2013 - 20:33:30 EST


On Tue, May 14, 2013 at 6:26 PM, Alexander Duyck
<alexander.h.duyck@xxxxxxxxx> wrote:
>
> 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@xxxxxxxxxx>
> Signed-off-by: Alexander Duyck <alexander.h.duyck@xxxxxxxxx>
> ---
>
> 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();


Alex, FWIW a similar patch was posted by Michael during the last rc
cycles of 3.9 see
http://marc.info/?l=linux-netdev&m=136569426119644&w=2
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