From aaf932e8161e45291cc85085b6d850f1bbdf53c8 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 21 May 2015 10:57:24 +0200 Subject: [PATCH] perf/x86/intel: Simplify the dynamic constraint code somewhat We have two 'struct event_constraint' local variables in intel_get_excl_constraints(): 'cx' and 'c'. Instead of using 'cx' after the dynamic allocation, put all 'cx' inside the dynamic allocation block and use 'c' outside of it. Also use direct assignment to copy the structure; let the compiler figure it out. Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Gleixner Cc: Vince Weaver Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/perf_event_intel.c | 21 ++++++++++----------- 1 file changed, 10 insertions(+), 11 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c index 5182cee16367..9588b8d1264d 100644 --- a/arch/x86/kernel/cpu/perf_event_intel.c +++ b/arch/x86/kernel/cpu/perf_event_intel.c @@ -1970,7 +1970,6 @@ static struct event_constraint * intel_get_excl_constraints(struct cpu_hw_events *cpuc, struct perf_event *event, int idx, struct event_constraint *c) { - struct event_constraint *cx; struct intel_excl_cntrs *excl_cntrs = cpuc->excl_cntrs; struct intel_excl_states *xlo; int tid = cpuc->excl_thread_id; @@ -1989,8 +1988,6 @@ intel_get_excl_constraints(struct cpu_hw_events *cpuc, struct perf_event *event, if (!excl_cntrs) return c; - cx = c; - /* * because we modify the constraint, we need * to make a copy. Static constraints come @@ -2000,6 +1997,7 @@ intel_get_excl_constraints(struct cpu_hw_events *cpuc, struct perf_event *event, * been cloned (marked dynamic) */ if (!(c->flags & PERF_X86_EVENT_DYNAMIC)) { + struct event_constraint *cx; /* sanity check */ if (idx < 0) @@ -2014,13 +2012,14 @@ intel_get_excl_constraints(struct cpu_hw_events *cpuc, struct perf_event *event, * initialize dynamic constraint * with static constraint */ - memcpy(cx, c, sizeof(*cx)); + *cx = *c; /* * mark constraint as dynamic, so we * can free it later on */ cx->flags |= PERF_X86_EVENT_DYNAMIC; + c = cx; } /* @@ -2054,37 +2053,37 @@ intel_get_excl_constraints(struct cpu_hw_events *cpuc, struct perf_event *event, * SHARED : sibling counter measuring non-exclusive event * UNUSED : sibling counter unused */ - for_each_set_bit(i, cx->idxmsk, X86_PMC_IDX_MAX) { + for_each_set_bit(i, c->idxmsk, X86_PMC_IDX_MAX) { /* * exclusive event in sibling counter * our corresponding counter cannot be used * regardless of our event */ if (xlo->state[i] == INTEL_EXCL_EXCLUSIVE) - __clear_bit(i, cx->idxmsk); + __clear_bit(i, c->idxmsk); /* * if measuring an exclusive event, sibling * measuring non-exclusive, then counter cannot * be used */ if (is_excl && xlo->state[i] == INTEL_EXCL_SHARED) - __clear_bit(i, cx->idxmsk); + __clear_bit(i, c->idxmsk); } /* * recompute actual bit weight for scheduling algorithm */ - cx->weight = hweight64(cx->idxmsk64); + c->weight = hweight64(c->idxmsk64); /* * if we return an empty mask, then switch * back to static empty constraint to avoid * the cost of freeing later on */ - if (cx->weight == 0) - cx = &emptyconstraint; + if (c->weight == 0) + c = &emptyconstraint; - return cx; + return c; } static struct event_constraint * -- 2.30.2