https://github.com/torvalds/linux
Revision 44bda4b7d26e9fffed6d7152d98a2e9edaeb2a76 authored by Hari Vyas on 03 July 2018, 09:05:41 UTC, committed by Bjorn Helgaas on 31 July 2018, 16:27:54 UTC
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>
1 parent a54e43f
Tip revision: 44bda4b7d26e9fffed6d7152d98a2e9edaeb2a76 authored by Hari Vyas on 03 July 2018, 09:05:41 UTC
PCI: Fix is_added/is_busmaster race condition
PCI: Fix is_added/is_busmaster race condition
Tip revision: 44bda4b
File | Mode | Size |
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accounting | ||
arch | ||
bpf | ||
build | ||
cgroup | ||
firewire | ||
gpio | ||
hv | ||
iio | ||
include | ||
kvm | ||
laptop | ||
leds | ||
lib | ||
memory-model | ||
nfsd | ||
objtool | ||
pci | ||
pcmcia | ||
perf | ||
power | ||
scripts | ||
spi | ||
testing | ||
thermal | ||
time | ||
usb | ||
virtio | ||
vm | ||
wmi | ||
Makefile | -rw-r--r-- | 5.4 KB |
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