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Davide Caratti f2cbd48528 net/sched: act_police: fix race condition on state variables 
after 'police' configuration parameters were converted to use RCU instead
of spinlock, the state variables used to compute the traffic rate (namely
'tcfp_toks', 'tcfp_ptoks' and 'tcfp_t_c') are erroneously read/updated in
the traffic path without any protection.

Use a dedicated spinlock to avoid race conditions on these variables, and
ensure proper cache-line alignment. In this way, 'police' is still faster
than what we observed when 'tcf_lock' was used in the traffic path _ i.e.
reverting commit 2d550dbad8 ("net/sched: act_police: don't use spinlock
in the data path"). Moreover, we preserve the throughput improvement that
was obtained after 'police' started using per-cpu counters, when 'avrate'
is used instead of 'rate'.

Changes since v1 (thanks to Eric Dumazet):
- call ktime_get_ns() before acquiring the lock in the traffic path
- use a dedicated spinlock instead of tcf_lock
- improve cache-line usage

Fixes: 2d550dbad8 ("net/sched: act_police: don't use spinlock in the data path")
Reported-and-suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
2018-11-20 14:59:58 -08:00
arch Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-11-18 10:54:59 -08:00
block
certs
crypto
Documentation Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-11-19 09:24:04 -08:00
drivers tg3: Add PHY reset for 5717/5719/5720 in change ring and flow control paths 2018-11-20 10:18:05 -08:00
firmware
fs Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-11-19 09:24:04 -08:00
include Revert "sctp: remove sctp_transport_pmtu_check" 2018-11-19 12:42:47 -08:00
init
ipc
kernel Merge branch 'akpm' (patches from Andrew) 2018-11-18 11:31:26 -08:00
lib lib/ubsan.c: don't mark __ubsan_handle_builtin_unreachable as noreturn 2018-11-18 10:15:10 -08:00
LICENSES
mm mm/memblock.c: fix a typo in __next_mem_pfn_range() comments 2018-11-18 10:15:10 -08:00
net net/sched: act_police: fix race condition on state variables 2018-11-20 14:59:58 -08:00
samples
scripts scripts/spdxcheck.py: make python3 compliant 2018-11-18 10:15:10 -08:00
security
sound
tools Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-11-19 09:24:04 -08:00
usr
virt
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.cocciconfig
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COPYING
CREDITS MAINTAINERS: update OMAP MMC entry 2018-11-18 10:15:09 -08:00
Kbuild
Kconfig
MAINTAINERS MAINTAINERS: add myself as co-maintainer for r8169 2018-11-20 14:22:45 -08:00
Makefile Linux 4.20-rc3 2018-11-18 13:33:44 -08:00
README

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.