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ce2fade187
[ Upstream commit 922b4b955a03d19fea98938f33ef0e62d01f5159 ]
The existing linked list based implementation of how ts tags are
assigned and managed is unsafe against concurrency and corner cases:
- element addition in tx processing can race against element removal
in ts queue completion,
- element removal in ts queue completion can race against element
removal in device close,
- if a large number of frames gets added to tx queue without ts queue
completions in between, elements with duplicate tag values can get
added.
Use a different implementation, based on per-port used tags bitmaps and
saved skb arrays.
Safety for addition in tx processing vs removal in ts completion is
provided by:
tag = find_first_zero_bit(...);
smp_mb();
<write rdev->ts_skb[tag]>
set_bit(...);
vs
<read rdev->ts_skb[tag]>
smp_mb();
clear_bit(...);
Safety for removal in ts completion vs removal in device close is
provided by using atomic read-and-clear for rdev->ts_skb[tag]:
ts_skb = xchg(&rdev->ts_skb[tag], NULL);
if (ts_skb)
<handle it>
Fixes: 33f5d733b5 ("net: renesas: rswitch: Improve TX timestamp accuracy")
Signed-off-by: Nikita Yushchenko <nikita.yoush@cogentembedded.com>
Link: https://patch.msgid.link/20241212062558.436455-1-nikita.yoush@cogentembedded.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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.