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authorAlexander Shishkin <alexander.shishkin@linux.intel.com>2017-03-30 18:39:56 +0300
committerIngo Molnar <mingo@kernel.org>2017-08-29 15:09:24 +0200
commit8d4e6c4caa12dafbcba138e5450b7af17b0b2194 (patch)
treea9b6c4f3076bd27f9a87fb67a2907c9a0a3c5cbd /kernel
parente0563e049531973e665db853e825a4efed9f881d (diff)
downloadlinux-8d4e6c4caa12dafbcba138e5450b7af17b0b2194.tar.bz2
perf/core, pt, bts: Get rid of itrace_started
I just noticed that hw.itrace_started and hw.config are aliased to the same location. Now, the PT driver happens to use both, which works out fine by sheer luck: - STORE(hw.itrace_start) is ordered before STORE(hw.config), in the program order, although there are no compiler barriers to ensure that, - to the perf_log_itrace_start() hw.itrace_start looks set at the same time as when it is intended to be set because both stores happen in the same path, - hw.config is never reset to zero in the PT driver. Now, the use of hw.config by the PT driver makes more sense (it being a HW PMU) than messing around with itrace_started, which is an awkward API to begin with. This patch replaces hw.itrace_started with an attach_state bit and an API call for the PMU drivers to use to communicate the condition. Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Cc: vince@deater.net Link: http://lkml.kernel.org/r/20170330153956.25994-1-alexander.shishkin@linux.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/events/core.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c
index e5467e107624..77fd6b11ef22 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7301,6 +7301,11 @@ static void perf_log_throttle(struct perf_event *event, int enable)
perf_output_end(&handle);
}
+void perf_event_itrace_started(struct perf_event *event)
+{
+ event->attach_state |= PERF_ATTACH_ITRACE;
+}
+
static void perf_log_itrace_start(struct perf_event *event)
{
struct perf_output_handle handle;
@@ -7316,7 +7321,7 @@ static void perf_log_itrace_start(struct perf_event *event)
event = event->parent;
if (!(event->pmu->capabilities & PERF_PMU_CAP_ITRACE) ||
- event->hw.itrace_started)
+ event->attach_state & PERF_ATTACH_ITRACE)
return;
rec.header.type = PERF_RECORD_ITRACE_START;