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Firo Yang f1f2eea30d enic: prevent waking up stopped tx queues over watchdog reset
[ Upstream commit 0f90522591fd09dd201065c53ebefdfe3c6b55cb ]

Recent months, our customer reported several kernel crashes all
preceding with following message:
NETDEV WATCHDOG: eth2 (enic): transmit queue 0 timed out
Error message of one of those crashes:
BUG: unable to handle kernel paging request at ffffffffa007e090

After analyzing severl vmcores, I found that most of crashes are
caused by memory corruption. And all the corrupted memory areas
are overwritten by data of network packets. Moreover, I also found
that the tx queues were enabled over watchdog reset.

After going through the source code, I found that in enic_stop(),
the tx queues stopped by netif_tx_disable() could be woken up over
a small time window between netif_tx_disable() and the
napi_disable() by the following code path:
napi_poll->
  enic_poll_msix_wq->
     vnic_cq_service->
        enic_wq_service->
           netif_wake_subqueue(enic->netdev, q_number)->
              test_and_clear_bit(__QUEUE_STATE_DRV_XOFF, &txq->state)
In turn, upper netowrk stack could queue skb to ENIC NIC though
enic_hard_start_xmit(). And this might introduce some race condition.

Our customer comfirmed that this kind of kernel crash doesn't occur over
90 days since they applied this patch.

Signed-off-by: Firo Yang <firo.yang@suse.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-02-24 08:36:21 +01:00
arch KVM: x86/mmu: Fix struct guest_walker arrays for 5-level paging 2020-02-19 19:53:09 +01:00
block
certs
crypto crypto: testmgr - don't try to decrypt uninitialized buffers 2020-02-14 16:34:18 -05:00
Documentation dt-bindings: iio: adc: ad7606: Fix wrong maxItems value 2020-02-14 16:34:19 -05:00
drivers enic: prevent waking up stopped tx queues over watchdog reset 2020-02-24 08:36:21 +01:00
fs ext4: choose hardlimit when softlimit is larger than hardlimit in ext4_statfs_project() 2020-02-19 19:53:09 +01:00
include gpio: add gpiod_toggle_active_low() 2020-02-19 19:53:09 +01:00
init
ipc
kernel sched/uclamp: Reject negative values in cpu_uclamp_write() 2020-02-19 19:53:07 +01:00
lib
LICENSES
mm mm/mmu_gather: invalidate TLB correctly on batch allocation failure and flush 2020-02-11 04:35:42 -08:00
net core: Don't skip generic XDP program execution for cloned SKBs 2020-02-24 08:36:21 +01:00
samples samples/bpf: Xdp_redirect_cpu fix missing tracepoint attach 2020-02-11 04:35:29 -08:00
scripts
security selinux: fall back to ref-walk if audit is required 2020-02-14 16:34:20 -05:00
sound ALSA: usb-audio: Add clock validity quirk for Denon MC7000/MCX8000 2020-02-19 19:52:57 +01:00
tools perf stat: Don't report a null stalled cycles per insn metric 2020-02-19 19:53:08 +01:00
usr
virt KVM: arm64: Treat emulated TVAL TimerValue as a signed 32-bit integer 2020-02-14 16:34:18 -05:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS
Makefile Linux 5.4.21 2020-02-19 19:53:10 +01:00
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.