perf_events: Undo some recursion damage
Make perf_swevent_get_recursion_context return a context number
and disable preemption.
This could be used to remove the IRQ disable from the trace bit
and index the per-cpu buffer with.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <20091123103819.993226816@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 50f11b5..0b0d5f7 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -3869,45 +3869,50 @@
}
}
-/*
- * Must be called with preemption disabled
- */
-int perf_swevent_get_recursion_context(int **recursion)
+int perf_swevent_get_recursion_context(void)
{
- struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
+ struct perf_cpu_context *cpuctx = &get_cpu_var(perf_cpu_context);
+ int rctx;
if (in_nmi())
- *recursion = &cpuctx->recursion[3];
+ rctx = 3;
else if (in_irq())
- *recursion = &cpuctx->recursion[2];
+ rctx = 2;
else if (in_softirq())
- *recursion = &cpuctx->recursion[1];
+ rctx = 1;
else
- *recursion = &cpuctx->recursion[0];
+ rctx = 0;
- if (**recursion)
+ if (cpuctx->recursion[rctx]) {
+ put_cpu_var(perf_cpu_context);
return -1;
+ }
- (**recursion)++;
+ cpuctx->recursion[rctx]++;
+ barrier();
- return 0;
+ return rctx;
}
EXPORT_SYMBOL_GPL(perf_swevent_get_recursion_context);
-void perf_swevent_put_recursion_context(int *recursion)
+void perf_swevent_put_recursion_context(int rctx)
{
- (*recursion)--;
+ struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
+ barrier();
+ cpuctx->recursion[rctx]++;
+ put_cpu_var(perf_cpu_context);
}
EXPORT_SYMBOL_GPL(perf_swevent_put_recursion_context);
-static void __do_perf_sw_event(enum perf_type_id type, u32 event_id,
- u64 nr, int nmi,
- struct perf_sample_data *data,
- struct pt_regs *regs)
+static void do_perf_sw_event(enum perf_type_id type, u32 event_id,
+ u64 nr, int nmi,
+ struct perf_sample_data *data,
+ struct pt_regs *regs)
{
+ struct perf_cpu_context *cpuctx;
struct perf_event_context *ctx;
- struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
+ cpuctx = &__get_cpu_var(perf_cpu_context);
rcu_read_lock();
perf_swevent_ctx_event(&cpuctx->ctx, type, event_id,
nr, nmi, data, regs);
@@ -3921,34 +3926,22 @@
rcu_read_unlock();
}
-static void do_perf_sw_event(enum perf_type_id type, u32 event_id,
- u64 nr, int nmi,
- struct perf_sample_data *data,
- struct pt_regs *regs)
-{
- int *recursion;
-
- preempt_disable();
-
- if (perf_swevent_get_recursion_context(&recursion))
- goto out;
-
- __do_perf_sw_event(type, event_id, nr, nmi, data, regs);
-
- perf_swevent_put_recursion_context(recursion);
-out:
- preempt_enable();
-}
-
void __perf_sw_event(u32 event_id, u64 nr, int nmi,
struct pt_regs *regs, u64 addr)
{
struct perf_sample_data data;
+ int rctx;
+
+ rctx = perf_swevent_get_recursion_context();
+ if (rctx < 0)
+ return;
data.addr = addr;
data.raw = NULL;
do_perf_sw_event(PERF_TYPE_SOFTWARE, event_id, nr, nmi, &data, regs);
+
+ perf_swevent_put_recursion_context(rctx);
}
static void perf_swevent_read(struct perf_event *event)
@@ -4172,7 +4165,7 @@
regs = task_pt_regs(current);
/* Trace events already protected against recursion */
- __do_perf_sw_event(PERF_TYPE_TRACEPOINT, event_id, count, 1,
+ do_perf_sw_event(PERF_TYPE_TRACEPOINT, event_id, count, 1,
&data, regs);
}
EXPORT_SYMBOL_GPL(perf_tp_event);
