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
..
bpf_jit_comp.c	bpf: Add __bpf_prog_{enter,exit}_struct_ops for struct_ops trampoline	2022-09-29 09:25:47 -07:00
bpf_jit_comp32.c	bpf: Change value of MAX_TAIL_CALL_CNT from 32 to 33	2021-11-16 14:03:15 +01:00
Makefile	treewide: Add SPDX license identifier - Makefile/Kconfig	2019-05-21 10:50:46 +02:00