perf/core: Add perf_pmu_resched() as global function

This patch add perf_pmu_resched() a global function that can be called
to force rescheduling of events for a given PMU. The function locks
both cpuctx and task_ctx internally. This will be used by a subsequent
patch.

Signed-off-by: Stephane Eranian <eranian@google.com>
[ Simplified the calling convention. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
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: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: kan.liang@intel.com
Cc: nelson.dsouza@intel.com
Cc: tonyj@suse.com
Link: https://lkml.kernel.org/r/20190408173252.37932-2-eranian@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

include/linux/perf_event.h

@@ -888,6 +888,9 @@ extern void perf_sched_cb_dec(struct pmu *pmu);
 extern void perf_sched_cb_inc(struct pmu *pmu);
 extern int perf_event_task_disable(void);
 extern int perf_event_task_enable(void);
+
+extern void perf_pmu_resched(struct pmu *pmu);
+
 extern int perf_event_refresh(struct perf_event *event, int refresh);
 extern void perf_event_update_userpage(struct perf_event *event);
 extern int perf_event_release_kernel(struct perf_event *event);

kernel/events/core.c

@@ -2478,6 +2478,16 @@ static void ctx_resched(struct perf_cpu_context *cpuctx,
 	perf_pmu_enable(cpuctx->ctx.pmu);
 }
 
+void perf_pmu_resched(struct pmu *pmu)
+{
+	struct perf_cpu_context *cpuctx = this_cpu_ptr(pmu->pmu_cpu_context);
+	struct perf_event_context *task_ctx = cpuctx->task_ctx;
+
+	perf_ctx_lock(cpuctx, task_ctx);
+	ctx_resched(cpuctx, task_ctx, EVENT_ALL|EVENT_CPU);
+	perf_ctx_unlock(cpuctx, task_ctx);
+}
+
 /*
  * Cross CPU call to install and enable a performance event
  *