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bpf: Remove migrate_disable in kprobe_multi_link_prog_run

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Graph tracer framework ensures we won't migrate, kprobe_multi_link_prog_run
called all the way from graph tracer, which disables preemption in
function_graph_enter_regs, as Jiri and Yonghong suggested, there is no
need to use migrate_disable. As a result, some overhead may will be reduced.
And add cant_sleep check for __this_cpu_inc_return.

Fixes: 0dcac27254 ("bpf: Add multi kprobe link")
Signed-off-by: Tao Chen <chen.dylane@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250814121430.2347454-1-chen.dylane@linux.dev
This commit is contained in:
Tao Chen
2025-08-14 20:14:29 +08:00
committed by Andrii Nakryiko
parent c80d797206
commit abdaf49be5
1 changed files with 7 additions and 2 deletions
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9
kernel/trace/bpf_trace.c
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@@ -2728,20 +2728,25 @@ kprobe_multi_link_prog_run(struct bpf_kprobe_multi_link *link,
struct pt_regs *regs;
int err;
/*
* graph tracer framework ensures we won't migrate, so there is no need
* to use migrate_disable for bpf_prog_run again. The check here just for
* __this_cpu_inc_return.
*/
cant_sleep();
if (unlikely(__this_cpu_inc_return(bpf_prog_active) != 1)) {
bpf_prog_inc_misses_counter(link->link.prog);
err = 1;
goto out;
}
migrate_disable();
rcu_read_lock();
regs = ftrace_partial_regs(fregs, bpf_kprobe_multi_pt_regs_ptr());
old_run_ctx = bpf_set_run_ctx(&run_ctx.session_ctx.run_ctx);
err = bpf_prog_run(link->link.prog, regs);
bpf_reset_run_ctx(old_run_ctx);
rcu_read_unlock();
migrate_enable();
out:
__this_cpu_dec(bpf_prog_active);