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Filename Latest commit message Latest commit date
Jacob Keller aaebaf50b5 ixgbe: fix race condition with PTP_TX_IN_PROGRESS bits
Hardware related to the ixgbe driver is limited to handling a single Tx
timestamp request at a time. Thus, the driver ignores requests for Tx
timestamp while waiting for the current request to finish. It uses
a state bit lock which enforces that only one timestamp request is
honored at a time.

Unfortunately this suffers from a simple race condition. The bit lock is
not cleared until after skb_tstamp_tx() is called notifying applications
of a new Tx timestamp. Even a well behaved application sending only one
packet at a time and waiting for a response can wake up and send a new
packet before the bit lock is cleared. This results in needlessly
dropping some Tx timestamp requests.

We can fix this by unlocking the state bit as soon as we read the
Timestamp register, as this is the first point at which it is safe to
unlock.

To avoid issues with the skb pointer, we'll use a copy of the pointer
and set the global variable in the driver structure to NULL first. This
ensures that the next timestamp request does not modify our local copy
of the skb pointer.

This ensures that well behaved applications do not accidentally race
with the unlock bit. Obviously an application which sends multiple Tx
timestamp requests at once will still only timestamp one packet at
a time. Unfortunately there is nothing we can do about this.

Reported-by: David Mirabito <davidm@metamako.com>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
2017-06-13 16:11:47 -07:00
arch ibmvnic: Client-initiated failover 2017-06-13 12:53:35 -04:00
block block: Avoid that blk_exit_rl() triggers a use-after-free 2017-06-01 13:07:55 -06:00
certs scripts/spelling.txt: add "intialise(d)" pattern and fix typo instances 2017-05-08 17:15:13 -07:00
crypto crypto: skcipher - Add missing API setkey checks 2017-05-18 13:04:05 +08:00
Documentation rxrpc: Provide a cmsg to specify the amount of Tx data for a call 2017-06-07 17:15:46 +01:00
drivers ixgbe: fix race condition with PTP_TX_IN_PROGRESS bits 2017-06-13 16:11:47 -07:00
firmware
fs rxrpc: Provide a cmsg to specify the amount of Tx data for a call 2017-06-07 17:15:46 +01:00
include net: dsa: Associate slave network device with CPU port 2017-06-13 16:35:03 -04:00
init Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-05-10 10:30:46 -07:00
ipc mm: introduce kv[mz]alloc helpers 2017-05-08 17:15:12 -07:00
kernel bpf: reset id on spilled regs in clear_all_pkt_pointers 2017-06-10 19:05:45 -04:00
lib networking: use skb_put_zero() 2017-06-13 13:54:03 -04:00
mm mm: consider memblock reservations for deferred memory initialization sizing 2017-06-02 15:07:38 -07:00
net net: dsa: Introduce dsa_get_cpu_port() 2017-06-13 16:35:03 -04:00
samples samples/bpf: add tests for more perf event types 2017-06-04 21:58:15 -04:00
scripts scripts/gdb: make lx-dmesg command work (reliably) 2017-06-02 15:07:38 -07:00
security Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-05-09 09:12:53 -07:00
sound sound fixes for 4.12-rc4 2017-06-02 09:40:47 -07:00
tools selftests/bpf: make correct use of exit codes in bpf selftests 2017-06-13 13:58:56 -04:00
usr initramfs: fix disabling of initramfs (and its compression) 2017-06-02 15:07:37 -07:00
virt KVM: arm/arm64: Hold slots_lock when unregistering kvm io bus devices 2017-05-18 11:18:16 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap power supply and reset changes for the v4.12 series (part 2) 2017-05-12 12:02:21 -07:00
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS wireless-drivers-next patches for 4.13 2017-06-12 10:14:29 -04:00
Makefile Linux 4.12-rc4 2017-06-04 16:47:43 -07:00
README

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

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

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.