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authorStephane Eranian <eranian@google.com>2011-06-06 16:57:08 +0200
committerIngo Molnar <mingo@elte.hu>2011-07-01 11:06:36 +0200
commitcd8a38d33e2528998998bae70a45ad27e442f114 (patch)
tree940bdcb466d498d32066d41529d04476185a42fd /arch
parentperf_events: Update Intel extra regs shared constraints management (diff)
downloadlinux-cd8a38d33e2528998998bae70a45ad27e442f114.tar.xz
linux-cd8a38d33e2528998998bae70a45ad27e442f114.zip
perf_events: Fix validation of events using an extra reg
The validate_group() function needs to validate events with extra shared regs. Within an event group, only events with the same value for the extra reg can co-exist. This was not checked by validate_group() because it was missing the shared_regs logic. This patch changes the allocation of the fake cpuc used for validation to also point to a fake shared_regs structure such that group events be properly testing. It modifies __intel_shared_reg_get_constraints() to use spin_lock_irqsave() to avoid lockdep issues. Signed-off-by: Stephane Eranian <eranian@google.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20110606145708.GA7279@quad Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/cpu/perf_event.c59
-rw-r--r--arch/x86/kernel/cpu/perf_event_intel.c16
2 files changed, 57 insertions, 18 deletions
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 019fda7489e7..9a0f55c99b6e 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -1689,6 +1689,40 @@ static int x86_pmu_commit_txn(struct pmu *pmu)
perf_pmu_enable(pmu);
return 0;
}
+/*
+ * a fake_cpuc is used to validate event groups. Due to
+ * the extra reg logic, we need to also allocate a fake
+ * per_core and per_cpu structure. Otherwise, group events
+ * using extra reg may conflict without the kernel being
+ * able to catch this when the last event gets added to
+ * the group.
+ */
+static void free_fake_cpuc(struct cpu_hw_events *cpuc)
+{
+ kfree(cpuc->shared_regs);
+ kfree(cpuc);
+}
+
+static struct cpu_hw_events *allocate_fake_cpuc(void)
+{
+ struct cpu_hw_events *cpuc;
+ int cpu = raw_smp_processor_id();
+
+ cpuc = kzalloc(sizeof(*cpuc), GFP_KERNEL);
+ if (!cpuc)
+ return ERR_PTR(-ENOMEM);
+
+ /* only needed, if we have extra_regs */
+ if (x86_pmu.extra_regs) {
+ cpuc->shared_regs = allocate_shared_regs(cpu);
+ if (!cpuc->shared_regs)
+ goto error;
+ }
+ return cpuc;
+error:
+ free_fake_cpuc(cpuc);
+ return ERR_PTR(-ENOMEM);
+}
/*
* validate that we can schedule this event
@@ -1699,9 +1733,9 @@ static int validate_event(struct perf_event *event)
struct event_constraint *c;
int ret = 0;
- fake_cpuc = kmalloc(sizeof(*fake_cpuc), GFP_KERNEL | __GFP_ZERO);
- if (!fake_cpuc)
- return -ENOMEM;
+ fake_cpuc = allocate_fake_cpuc();
+ if (IS_ERR(fake_cpuc))
+ return PTR_ERR(fake_cpuc);
c = x86_pmu.get_event_constraints(fake_cpuc, event);
@@ -1711,7 +1745,7 @@ static int validate_event(struct perf_event *event)
if (x86_pmu.put_event_constraints)
x86_pmu.put_event_constraints(fake_cpuc, event);
- kfree(fake_cpuc);
+ free_fake_cpuc(fake_cpuc);
return ret;
}
@@ -1731,35 +1765,32 @@ static int validate_group(struct perf_event *event)
{
struct perf_event *leader = event->group_leader;
struct cpu_hw_events *fake_cpuc;
- int ret, n;
+ int ret = -ENOSPC, n;
- ret = -ENOMEM;
- fake_cpuc = kmalloc(sizeof(*fake_cpuc), GFP_KERNEL | __GFP_ZERO);
- if (!fake_cpuc)
- goto out;
+ fake_cpuc = allocate_fake_cpuc();
+ if (IS_ERR(fake_cpuc))
+ return PTR_ERR(fake_cpuc);
/*
* the event is not yet connected with its
* siblings therefore we must first collect
* existing siblings, then add the new event
* before we can simulate the scheduling
*/
- ret = -ENOSPC;
n = collect_events(fake_cpuc, leader, true);
if (n < 0)
- goto out_free;
+ goto out;
fake_cpuc->n_events = n;
n = collect_events(fake_cpuc, event, false);
if (n < 0)
- goto out_free;
+ goto out;
fake_cpuc->n_events = n;
ret = x86_pmu.schedule_events(fake_cpuc, n, NULL);
-out_free:
- kfree(fake_cpuc);
out:
+ free_fake_cpuc(fake_cpuc);
return ret;
}
diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c
index 6ad95baff856..ac02b83e8614 100644
--- a/arch/x86/kernel/cpu/perf_event_intel.c
+++ b/arch/x86/kernel/cpu/perf_event_intel.c
@@ -1027,14 +1027,18 @@ __intel_shared_reg_get_constraints(struct cpu_hw_events *cpuc,
{
struct event_constraint *c = &emptyconstraint;
struct er_account *era;
+ unsigned long flags;
/* already allocated shared msr */
- if (reg->alloc || !cpuc->shared_regs)
+ if (reg->alloc)
return &unconstrained;
era = &cpuc->shared_regs->regs[reg->idx];
-
- raw_spin_lock(&era->lock);
+ /*
+ * we use spin_lock_irqsave() to avoid lockdep issues when
+ * passing a fake cpuc
+ */
+ raw_spin_lock_irqsave(&era->lock, flags);
if (!atomic_read(&era->ref) || era->config == reg->config) {
@@ -1058,7 +1062,7 @@ __intel_shared_reg_get_constraints(struct cpu_hw_events *cpuc,
*/
c = &unconstrained;
}
- raw_spin_unlock(&era->lock);
+ raw_spin_unlock_irqrestore(&era->lock, flags);
return c;
}
@@ -1524,4 +1528,8 @@ static int intel_pmu_init(void)
return 0;
}
+static struct intel_shared_regs *allocate_shared_regs(int cpu)
+{
+ return NULL;
+}
#endif /* CONFIG_CPU_SUP_INTEL */