Commit 4223bf83 authored by Tao Chen's avatar Tao Chen Committed by Andrii Nakryiko
Browse files

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: d9c9e4db ("bpf: Factorize bpf_trace_printk and bpf_seq_printf")
Signed-off-by: default avatarTao Chen <chen.dylane@linux.dev>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250819125638.2544715-1-chen.dylane@linux.dev
parent d47cc4de

kernel/bpf/helpers.c

+0 −3
Original line number Diff line number Diff line
@@ -774,11 +774,9 @@ int bpf_try_get_buffers(struct bpf_bprintf_buffers **bufs) 
{

	int nest_level;



	preempt_disable();

	nest_level = this_cpu_inc_return(bpf_bprintf_nest_level);

	if (WARN_ON_ONCE(nest_level > MAX_BPRINTF_NEST_LEVEL)) {

		this_cpu_dec(bpf_bprintf_nest_level);

		preempt_enable();

		return -EBUSY;

	}

	*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))

		return;

	this_cpu_dec(bpf_bprintf_nest_level);

	preempt_enable();

}



void bpf_bprintf_cleanup(struct bpf_bprintf_data *data)