perf/x86/intel: Simplify put_exclusive_constraints()

Don't bother with taking locks if we're not actually going to do
anything. Also, drop the _irqsave(), this is very much only called
from IRQ-disabled context.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c
index f3201439031d580376e534d703f0ac9b95e81d22..74f19d9268bbd49f9496ca39df4553643751bea9 100644 (file)
--- a/arch/x86/kernel/cpu/perf_event_intel.c
+++ b/arch/x86/kernel/cpu/perf_event_intel.c
@@ -2130,7 +2130,6 @@ static void intel_put_excl_constraints(struct cpu_hw_events *cpuc,
        struct intel_excl_cntrs *excl_cntrs = cpuc->excl_cntrs;
        int tid = cpuc->excl_thread_id;
        struct intel_excl_states *xl;
-       unsigned long flags = 0; /* keep compiler happy */
 
        /*
         * nothing needed if in group validation mode
@@ -2141,7 +2140,6 @@ static void intel_put_excl_constraints(struct cpu_hw_events *cpuc,
        if (WARN_ON_ONCE(!excl_cntrs))
                return;
 
-       xl = &excl_cntrs->states[tid];
        if (hwc->flags & PERF_X86_EVENT_EXCL_ACCT) {
                hwc->flags &= ~PERF_X86_EVENT_EXCL_ACCT;
                if (!--cpuc->n_excl)
@@ -2149,22 +2147,25 @@ static void intel_put_excl_constraints(struct cpu_hw_events *cpuc,
        }
 
        /*
-        * put_constraint may be called from x86_schedule_events()
-        * which already has the lock held so here make locking
-        * conditional
+        * If event was actually assigned, then mark the counter state as
+        * unused now.
         */
-       if (!xl->sched_started)
-               raw_spin_lock_irqsave(&excl_cntrs->lock, flags);
+       if (hwc->idx >= 0) {
+               xl = &excl_cntrs->states[tid];
+
+               /*
+                * put_constraint may be called from x86_schedule_events()
+                * which already has the lock held so here make locking
+                * conditional.
+                */
+               if (!xl->sched_started)
+                       raw_spin_lock(&excl_cntrs->lock);
 
-       /*
-        * if event was actually assigned, then mark the
-        * counter state as unused now
-        */
-       if (hwc->idx >= 0)
                xl->state[hwc->idx] = INTEL_EXCL_UNUSED;
 
-       if (!xl->sched_started)
-               raw_spin_unlock_irqrestore(&excl_cntrs->lock, flags);
+               if (!xl->sched_started)
+                       raw_spin_unlock(&excl_cntrs->lock);
+       }
 }
 
 static void