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Filename Latest commit message Latest commit date
Stuart Hayes 4667358dab PCI: pciehp: Fix MSI interrupt race
[ Upstream commit 8edf5332c39340b9583cf9cba659eb7ec71f75b5 ]

Without this commit, a PCIe hotplug port can stop generating interrupts on
hotplug events, so device adds and removals will not be seen:

The pciehp interrupt handler pciehp_isr() reads the Slot Status register
and then writes back to it to clear the bits that caused the interrupt.  If
a different interrupt event bit gets set between the read and the write,
pciehp_isr() returns without having cleared all of the interrupt event
bits.  If this happens when the MSI isn't masked (which by default it isn't
in handle_edge_irq(), and which it will never be when MSI per-vector
masking is not supported), we won't get any more hotplug interrupts from
that device.

That is expected behavior, according to the PCIe Base Spec r5.0, section
6.7.3.4, "Software Notification of Hot-Plug Events".

Because the Presence Detect Changed and Data Link Layer State Changed event
bits can both get set at nearly the same time when a device is added or
removed, this is more likely to happen than it might seem.  The issue was
found (and can be reproduced rather easily) by connecting and disconnecting
an NVMe storage device on at least one system model where the NVMe devices
were being connected to an AMD PCIe port (PCI device 0x1022/0x1483).

Fix the issue by modifying pciehp_isr() to loop back and re-read the Slot
Status register immediately after writing to it, until it sees that all of
the event status bits have been cleared.

[lukas: drop loop count limitation, write "events" instead of "status",
don't loop back in INTx and poll modes, tweak code comment & commit msg]
Link: https://lore.kernel.org/r/78b4ced5072bfe6e369d20e8b47c279b8c7af12e.1582121613.git.lukas@wunner.de
Tested-by: Stuart Hayes <stuart.w.hayes@gmail.com>
Signed-off-by: Stuart Hayes <stuart.w.hayes@gmail.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-10-01 13:17:52 +02:00
arch KVM: LAPIC: Mark hrtimer for period or oneshot mode to expire in hard interrupt context 2020-10-01 13:17:45 +02:00
block block: only call sched requeue_request() for scheduled requests 2020-09-23 12:40:37 +02:00
certs
crypto crypto: af_alg - Work around empty control messages without MSG_MORE 2020-09-03 11:27:05 +02:00
Documentation affs: fix basic permission bits to actually work 2020-09-09 19:12:34 +02:00
drivers PCI: pciehp: Fix MSI interrupt race 2020-10-01 13:17:52 +02:00
fs ubifs: Fix out-of-bounds memory access caused by abnormal value of node_len 2020-10-01 13:17:51 +02:00
include PCI: Use ioremap(), not phys_to_virt() for platform ROM 2020-10-01 13:17:51 +02:00
init exec: Add exec_update_mutex to replace cred_guard_mutex 2020-10-01 13:17:47 +02:00
ipc
kernel perf: Use new infrastructure to fix deadlocks in execve 2020-10-01 13:17:48 +02:00
lib kernel/sysctl-test: Add null pointer test for sysctl.c:proc_dointvec() 2020-10-01 13:17:10 +02:00
LICENSES
mm mm: avoid data corruption on CoW fault into PFN-mapped VMA 2020-10-01 13:17:39 +02:00
net netfilter: nf_tables: silence a RCU-list warning in nft_table_lookup() 2020-10-01 13:17:51 +02:00
samples bpf: Fix fds_example SIGSEGV error 2020-08-19 08:16:03 +02:00
scripts checkpatch: fix the usage of capture group ( ... ) 2020-09-09 19:12:37 +02:00
security selinux: sel_avc_get_stat_idx should increase position index 2020-10-01 13:17:32 +02:00
sound ALSA: usb-audio: Fix case when USB MIDI interface has more than one extra endpoint descriptor 2020-10-01 13:17:52 +02:00
tools selftests/ptrace: add test cases for dead-locks 2020-10-01 13:17:48 +02:00
usr
virt KVM: fix overflow of zero page refcount with ksm running 2020-10-01 13:17:31 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
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.gitignore
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COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS Documentation/llvm: add documentation on building w/ Clang/LLVM 2020-08-26 10:40:46 +02:00
Makefile Linux 5.4.68 2020-09-26 18:03:16 +02:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.