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Martin KaFai Lau 64696c40d0 bpf: Add __bpf_prog_{enter,exit}_struct_ops for struct_ops trampoline
The struct_ops prog is to allow using bpf to implement the functions in
a struct (eg. kernel module).  The current usage is to implement the
tcp_congestion.  The kernel does not call the tcp-cc's ops (ie.
the bpf prog) in a recursive way.

The struct_ops is sharing the tracing-trampoline's enter/exit
function which tracks prog->active to avoid recursion.  It is
needed for tracing prog.  However, it turns out the struct_ops
bpf prog will hit this prog->active and unnecessarily skipped
running the struct_ops prog.  eg.  The '.ssthresh' may run in_task()
and then interrupted by softirq that runs the same '.ssthresh'.
Skip running the '.ssthresh' will end up returning random value
to the caller.

The patch adds __bpf_prog_{enter,exit}_struct_ops for the
struct_ops trampoline.  They do not track the prog->active
to detect recursion.

One exception is when the tcp_congestion's '.init' ops is doing
bpf_setsockopt(TCP_CONGESTION) and then recurs to the same
'.init' ops.  This will be addressed in the following patches.

Fixes: ca06f55b90 ("bpf: Add per-program recursion prevention mechanism")
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20220929070407.965581-2-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-09-29 09:25:47 -07:00
arch bpf: Add __bpf_prog_{enter,exit}_struct_ops for struct_ops trampoline 2022-09-29 09:25:47 -07:00
block
certs
crypto
Documentation bpf: Tweak definition of KF_TRUSTED_ARGS 2022-09-21 19:25:26 -07:00
drivers net: moxa: fix endianness-related issues from 'sparse' 2022-09-06 10:24:42 +02:00
fs Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-09-01 12:58:02 -07:00
include bpf: Add __bpf_prog_{enter,exit}_struct_ops for struct_ops trampoline 2022-09-29 09:25:47 -07:00
init
io_uring
ipc
kernel bpf: Add __bpf_prog_{enter,exit}_struct_ops for struct_ops trampoline 2022-09-29 09:25:47 -07:00
lib
LICENSES
mm
net skmsg: Schedule psock work if the cached skb exists on the psock 2022-09-26 17:48:05 +02:00
samples samples/bpf: Replace blk_account_io_done() with __blk_account_io_done() 2022-09-20 17:25:59 -07:00
scripts Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2022-09-06 23:21:18 +02:00
security KEYS: Move KEY_LOOKUP_ to include/linux/key.h and define KEY_LOOKUP_ALL 2022-09-21 17:32:48 -07:00
sound
tools selftests/bpf: Convert udp_limit test to ASSERT_* macros 2022-09-28 17:34:19 -07:00
usr
virt
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS net: pcs: add new PCS driver for altera TSE PCS 2022-09-05 10:16:53 +01:00
Makefile
README

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

There are several guides for kernel developers and users. These guides can
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Documentation/admin-guide/README.rst first.

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