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Message-Id: <a6118cc34edd338143f92d5218611638aade286f.1467106475.git.daniel@iogearbox.net> Date: Tue, 28 Jun 2016 12:18:24 +0200 From: Daniel Borkmann <daniel@...earbox.net> To: davem@...emloft.net Cc: alexei.starovoitov@...il.com, tgraf@...g.ch, netdev@...r.kernel.org, Daniel Borkmann <daniel@...earbox.net> Subject: [PATCH net-next 2/6] 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@...earbox.net> Acked-by: Alexei Starovoitov <ast@...nel.org> --- kernel/trace/bpf_trace.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 4e61f74..505f9e9 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -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); -- 1.9.3
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