diff options
| author | Hari Vyas <hari.vyas@broadcom.com> | 2018-07-03 14:35:41 +0530 |
|---|---|---|
| committer | Bjorn Helgaas <bhelgaas@google.com> | 2018-07-31 11:27:54 -0500 |
| commit | 44bda4b7d26e9fffed6d7152d98a2e9edaeb2a76 (patch) | |
| tree | 46ed284871234e825bc3211dd5bf0d960b7c3cda /drivers/pci/probe.c | |
| parent | a54e43f993f8ec2f063b616a0e4d2b09e08d78a5 (diff) | |
PCI: Fix is_added/is_busmaster race condition
When a PCI device is detected, pdev->is_added is set to 1 and proc and
sysfs entries are created.
When the device is removed, pdev->is_added is checked for one and then
device is detached with clearing of proc and sys entries and at end,
pdev->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 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 the PCI core setting the
is_added bit in pci_bus_add_device() and the NVMe driver reset work-queue
setting the is_busmaster bit in pci_set_master(). As these fields are not
handled atomically, that clears the is_added bit.
Move the is_added bit to a separate private flag variable and use atomic
functions to set and retrieve the device addition state. This avoids the
race because is_added no longer shares a memory location with is_busmaster.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=200283
Signed-off-by: Hari Vyas <hari.vyas@broadcom.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Lukas Wunner <lukas@wunner.de>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'drivers/pci/probe.c')
| -rw-r--r-- | drivers/pci/probe.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index ac876e32de4b..611adcd9c169 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -2433,13 +2433,13 @@ int pci_scan_slot(struct pci_bus *bus, int devfn) dev = pci_scan_single_device(bus, devfn); if (!dev) return 0; - if (!dev->is_added) + if (!pci_dev_is_added(dev)) nr++; for (fn = next_fn(bus, dev, 0); fn > 0; fn = next_fn(bus, dev, fn)) { dev = pci_scan_single_device(bus, devfn + fn); if (dev) { - if (!dev->is_added) + if (!pci_dev_is_added(dev)) nr++; dev->multifunction = 1; } |