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bpf: Remove preempt_disable in bpf_try_get_buffers 

Now BPF program will run with migration disabled, so it is safe
to access this_cpu_inc_return(bpf_bprintf_nest_level).

Fixes: d9c9e4db18 ("bpf: Factorize bpf_trace_printk and bpf_seq_printf")
Signed-off-by: Tao Chen <chen.dylane@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250819125638.2544715-1-chen.dylane@linux.dev
This commit is contained in:
Tao Chen 2025-08-19 20:56:38 +08:00 committed by Andrii Nakryiko
parent d47cc4dea1
commit 4223bf833c
1 changed files with 0 additions and 3 deletions
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3
kernel/bpf/helpers.c
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@ -774,11 +774,9 @@ int bpf_try_get_buffers(struct bpf_bprintf_buffers **bufs)
{ {
int nest_level; int nest_level;
preempt_disable();
nest_level = this_cpu_inc_return(bpf_bprintf_nest_level); nest_level = this_cpu_inc_return(bpf_bprintf_nest_level);
if (WARN_ON_ONCE(nest_level > MAX_BPRINTF_NEST_LEVEL)) { if (WARN_ON_ONCE(nest_level > MAX_BPRINTF_NEST_LEVEL)) {
this_cpu_dec(bpf_bprintf_nest_level); this_cpu_dec(bpf_bprintf_nest_level);
preempt_enable();
return -EBUSY; return -EBUSY;
} }
*bufs = this_cpu_ptr(&bpf_bprintf_bufs[nest_level - 1]); *bufs = this_cpu_ptr(&bpf_bprintf_bufs[nest_level - 1]);
@ -791,7 +789,6 @@ void bpf_put_buffers(void)
if (WARN_ON_ONCE(this_cpu_read(bpf_bprintf_nest_level) == 0)) if (WARN_ON_ONCE(this_cpu_read(bpf_bprintf_nest_level) == 0))
return; return;
this_cpu_dec(bpf_bprintf_nest_level); this_cpu_dec(bpf_bprintf_nest_level);
preempt_enable();
} }
void bpf_bprintf_cleanup(struct bpf_bprintf_data *data) void bpf_bprintf_cleanup(struct bpf_bprintf_data *data)