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 |
---|---|---|
ac97 | ||
aoa | ||
arm | ||
atmel | ||
core | ||
drivers | ||
firewire | ||
hda | ||
i2c | ||
isa | ||
mips | ||
oss | ||
parisc | ||
pci | ||
pcmcia | ||
ppc | ||
sh | ||
soc | ||
sparc | ||
spi | ||
synth | ||
usb | ||
x86 | ||
xen | ||
Kconfig | -rw-r--r-- | 2.7 KB |
Makefile | -rw-r--r-- | 554 bytes |
ac97_bus.c | -rw-r--r-- | 3.1 KB |
last.c | -rw-r--r-- | 1.2 KB |
sound_core.c | -rw-r--r-- | 14.5 KB |
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