From: Bjorn Helgaas <bhelgaas@google.com>
To: hari.vyas@broadcom.com
Cc: Bjorn Helgaas <helgaas@kernel.org>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
linux-pci@vger.kernel.org, Ray Jui <ray.jui@broadcom.com>
Subject: Re: [PATCH v3] PCI: Data corruption happening due to race condition
Date: Fri, 20 Jul 2018 07:20:40 -0500 [thread overview]
Message-ID: <CAErSpo4FfjHUMMLT_=fvX=cVkoUF0ApdEimZbxswen+Z8TqvSA@mail.gmail.com> (raw)
In-Reply-To: <CAM5rFu9ZKpeKGhS+8cn3p0wKP0+GQrtexboxtwgGfDms3oBX0w@mail.gmail.com>
On Fri, Jul 20, 2018 at 4:16 AM Hari Vyas <hari.vyas@broadcom.com> wrote:
>
> On Thu, Jul 19, 2018 at 11:11 PM, Bjorn Helgaas <helgaas@kernel.org> wrote:
> > On Tue, Jul 03, 2018 at 02:35:41PM +0530, Hari Vyas wrote:
> >> When a pci device is detected, a variable is_added is set to
> >> 1 in pci device structure and proc, sys entries are created.
> >>
> >> When a pci device is removed, first is_added is checked for one
> >> and then device is detached with clearing of proc and sys
> >> entries and at end, is_added is set to 0.
> >>
> >> is_added and is_busmaster are bit fields in pci_dev structure
> >> sharing same memory location.
> >>
> >> A strange issue was observed with multiple times removal and
> >> rescan of a pcie nvme device using sysfs commands where is_added
> >> flag was observed as zero instead of one while removing device
> >> and proc,sys entries are not cleared. This causes issue in
> >> later device addition with warning message "proc_dir_entry"
> >> already registered.
> >>
> >> Debugging revealed a race condition between pcie core driver
> >> enabling is_added bit(pci_bus_add_device()) and nvme driver
> >> reset work-queue enabling is_busmaster bit (by pci_set_master()).
> >> As both fields are not handled in atomic manner and that clears
> >> is_added bit.
> >>
> >> Fix moves device addition is_added bit to separate private flag
> >> variable and use different atomic functions to set and retrieve
> >> device addition state. As is_added shares different memory
> >> location so race condition is avoided.
> >
> > If/when you post a v4 of this, can you include the bugzilla URL
> > right here, i.e.,
> >
> > Link: https://bugzilla.kernel.org/show_bug.cgi?id=200283
> >> Signed-off-by: Hari Vyas <hari.vyas@broadcom.com>
> >
> > That way we can connect the commit with the bugzilla, which contains
> > more information that may be useful in the future.
> Bit confused. Do I need to change commit message for including bugzila link ?
> Believe v3 should be Okay from code perspective time-being. Please confirm
You don't need to repost it just to update the commit message (I'll
try to remember to add the link when I apply it). But if you do
repost it for some other reason, it helps me out if you include the
link.
next prev parent reply other threads:[~2018-07-20 12:20 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-03 9:05 [PATCH v3] PCI: Data corruption happening due to race condition Hari Vyas
2018-07-03 9:05 ` Hari Vyas
2018-07-03 9:13 ` Lukas Wunner
2018-07-18 23:29 ` Bjorn Helgaas
2018-07-19 4:18 ` Benjamin Herrenschmidt
2018-07-19 14:04 ` Hari Vyas
2018-07-19 18:55 ` Lukas Wunner
2018-07-20 4:27 ` Benjamin Herrenschmidt
2018-07-27 22:25 ` Bjorn Helgaas
2018-07-28 0:45 ` Benjamin Herrenschmidt
2018-07-31 11:21 ` Michael Ellerman
2018-07-19 17:41 ` Bjorn Helgaas
2018-07-20 9:16 ` Hari Vyas
2018-07-20 12:20 ` Bjorn Helgaas [this message]
2018-07-31 16:37 ` Bjorn Helgaas
2018-08-15 3:35 ` PCIe enable device races (Was: [PATCH v3] PCI: Data corruption happening due to race condition) Benjamin Herrenschmidt
2018-08-15 4:16 ` Benjamin Herrenschmidt
2018-08-15 4:44 ` Benjamin Herrenschmidt
2018-08-15 5:21 ` [RFC PATCH] pci: Proof of concept at fixing pci_enable_device/bridge races Benjamin Herrenschmidt
2018-08-15 19:09 ` PCIe enable device races (Was: [PATCH v3] PCI: Data corruption happening due to race condition) Bjorn Helgaas
2018-08-15 21:50 ` [RFC PATCH] pci: Proof of concept at fixing pci_enable_device/bridge races Benjamin Herrenschmidt
2018-08-15 22:40 ` Guenter Roeck
2018-08-15 23:38 ` Benjamin Herrenschmidt
2018-08-20 1:31 ` Guenter Roeck
2018-08-17 3:07 ` Bjorn Helgaas
2018-08-17 3:42 ` Benjamin Herrenschmidt
2018-08-15 18:50 ` PCIe enable device races (Was: [PATCH v3] PCI: Data corruption happening due to race condition) Bjorn Helgaas
2018-08-15 21:52 ` Benjamin Herrenschmidt
2018-08-15 23:23 ` Benjamin Herrenschmidt
2018-08-16 7:58 ` Konstantin Khlebnikov
2018-08-16 8:02 ` Benjamin Herrenschmidt
2018-08-16 9:22 ` Hari Vyas
2018-08-16 10:10 ` Benjamin Herrenschmidt
2018-08-16 10:11 ` Benjamin Herrenschmidt
2018-08-16 10:26 ` Lukas Wunner
2018-08-16 10:47 ` Hari Vyas
2018-08-16 23:20 ` Benjamin Herrenschmidt
2018-08-16 23:17 ` Benjamin Herrenschmidt
2018-08-17 0:43 ` Benjamin Herrenschmidt
2018-08-16 19:43 ` Jens Axboe
2018-08-16 21:37 ` Benjamin Herrenschmidt
2018-08-16 21:56 ` Jens Axboe
2018-08-16 23:09 ` Benjamin Herrenschmidt
2018-08-17 0:14 ` Jens Axboe
2018-08-16 12:28 ` Lukas Wunner
2018-08-16 23:25 ` Benjamin Herrenschmidt
2018-08-17 1:12 ` Benjamin Herrenschmidt
2018-08-17 16:39 ` Lukas Wunner
2018-08-18 3:37 ` Benjamin Herrenschmidt
2018-08-18 9:22 ` Lukas Wunner
2018-08-18 13:11 ` Benjamin Herrenschmidt
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