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bpf, trace: fetch current cpu only once 

We currently have two invocations, which is unnecessary. Fetch it only
once and use the smp_processor_id() variant, so we also get preemption
checks along with it when DEBUG_PREEMPT is set.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Daniel Borkmann 2016-06-28 12:18:24 +02:00 committed by David S. Miller
parent 1ca1cc98bf
commit d793133031
1 changed files with 3 additions and 2 deletions
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5
kernel/trace/bpf_trace.c
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@ -233,6 +233,7 @@ static u64 bpf_perf_event_output(u64 r1, u64 r2, u64 flags, u64 r4, u64 size)
struct pt_regs *regs = (struct pt_regs *) (long) r1;
struct bpf_map *map = (struct bpf_map *) (long) r2;
struct bpf_array *array = container_of(map, struct bpf_array, map);
unsigned int cpu = smp_processor_id();
u64 index = flags & BPF_F_INDEX_MASK;
void *data = (void *) (long) r4;
struct perf_sample_data sample_data;
@ -246,7 +247,7 @@ static u64 bpf_perf_event_output(u64 r1, u64 r2, u64 flags, u64 r4, u64 size)
if (unlikely(flags & ~(BPF_F_INDEX_MASK)))
return -EINVAL;
if (index == BPF_F_CURRENT_CPU)
index = raw_smp_processor_id();
index = cpu;
if (unlikely(index >= array->map.max_entries))
return -E2BIG;
@ -259,7 +260,7 @@ static u64 bpf_perf_event_output(u64 r1, u64 r2, u64 flags, u64 r4, u64 size)
event->attr.config != PERF_COUNT_SW_BPF_OUTPUT))
return -EINVAL;
if (unlikely(event->oncpu != smp_processor_id()))
if (unlikely(event->oncpu != cpu))
return -EOPNOTSUPP;
perf_sample_data_init(&sample_data, 0, 0);