From: Bjorn Helgaas <bhelgaas@google.com>
To: Sandeep Mann <sandeep@purestorage.com>
Cc: linux-pci@vger.kernel.org, Rajat Jain <rajatxjain@gmail.com>
Subject: Re: [PATCH] PCI: pciehp: Use ordered workqueue for HPC events
Date: Tue, 12 Aug 2014 16:00:58 -0600 [thread overview]
Message-ID: <20140812213626.GA6333@google.com> (raw)
In-Reply-To: <1406933232-1560-1-git-send-email-sandeep@purestorage.com>
[+cc Rajat]
On Fri, Aug 01, 2014 at 03:47:12PM -0700, Sandeep Mann wrote:
> Using an ordered workqueue serializes processing of hotplug event. Processing
> an hotplug event for some devices can take a relatively "long" time, which
> means if a device is added and removed in quick succession (or due to flacky
> hardware), it can lead to multiple outstanding hotplug events. Processing
> these events concurrently can lead to unknown internal state and/or kernel
> panics.
Did you find this by code inspection, or did you actually observe a
problem? If the latter, what were the symptoms?
shpchp does the same thing, so I assume it requires the same fix.
> Signed-off-by: Sandeep Mann <sandeep@purestorage.com>
> ---
> drivers/pci/hotplug/pciehp_hpc.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
> index 42914e0..c4eedab 100644
> --- a/drivers/pci/hotplug/pciehp_hpc.c
> +++ b/drivers/pci/hotplug/pciehp_hpc.c
> @@ -681,7 +681,7 @@ static int pcie_init_slot(struct controller *ctrl)
> if (!slot)
> return -ENOMEM;
>
> - slot->wq = alloc_workqueue("pciehp-%u", 0, 0, PSN(ctrl));
> + slot->wq = alloc_ordered_workqueue("pciehp-%u", 0, PSN(ctrl));
> if (!slot->wq)
> goto abort;
>
> --
> 1.8.3.2
>
next prev parent reply other threads:[~2014-08-12 22:01 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-01 22:47 [PATCH] PCI: pciehp: Use ordered workqueue for HPC events Sandeep Mann
2014-08-04 20:22 ` Rajat Jain
2014-08-12 22:00 ` Bjorn Helgaas [this message]
2014-08-12 22:30 ` Sandeep S Mann
2014-08-12 23:31 ` Rajat Jain
2014-08-13 0:09 ` Sandeep S Mann
2014-08-13 0:33 ` Rajat Jain
2014-08-13 17:00 ` Sandeep S Mann
2014-09-04 21:10 ` Bjorn Helgaas
2014-11-04 8:10 ` Rajat Jain
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