1 files changed, 45 insertions, 23 deletions

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 718fa939b1a7..aba822722300 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -3880,34 +3880,42 @@ static void perf_swevent_ctx_event(struct perf_event_context *ctx,
         }
 }
 
-static int *perf_swevent_recursion_context(struct perf_cpu_context *cpuctx)
+/*
+ * Must be called with preemption disabled
+ */
+int perf_swevent_get_recursion_context(int **recursion)
 {
+        struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
+
         if (in_nmi())
-                return &cpuctx->recursion[3];
+                *recursion = &cpuctx->recursion[3];
+        else if (in_irq())
+                *recursion = &cpuctx->recursion[2];
+        else if (in_softirq())
+                *recursion = &cpuctx->recursion[1];
+        else
+                *recursion = &cpuctx->recursion[0];
 
-        if (in_irq())
-                return &cpuctx->recursion[2];
+        if (**recursion)
+                return -1;
 
-        if (in_softirq())
-                return &cpuctx->recursion[1];
+        (**recursion)++;
 
-        return &cpuctx->recursion[0];
+        return 0;
 }
 
-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)
+void perf_swevent_put_recursion_context(int *recursion)
 {
-        struct perf_cpu_context *cpuctx = &get_cpu_var(perf_cpu_context);
-        int *recursion = perf_swevent_recursion_context(cpuctx);
-        struct perf_event_context *ctx;
-
-        if (*recursion)
-                goto out;
+        (*recursion)--;
+}
 
-        (*recursion)++;
-        barrier();
+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_event_context *ctx;
+        struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
 
         rcu_read_lock();
         perf_swevent_ctx_event(&cpuctx->ctx, type, event_id,
@@ -3920,12 +3928,25 @@ static void do_perf_sw_event(enum perf_type_id type, u32 event_id,
         if (ctx)
                 perf_swevent_ctx_event(ctx, type, event_id, nr, nmi, data, regs);
         rcu_read_unlock();
+}
 
-        barrier();
-        (*recursion)--;
+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:
-        put_cpu_var(perf_cpu_context);
+        preempt_enable();
 }
 
 void __perf_sw_event(u32 event_id, u64 nr, int nmi,
@@ -4159,7 +4180,8 @@ void perf_tp_event(int event_id, u64 addr, u64 count, void *record,
         if (!regs)
                 regs = task_pt_regs(current);
 
-        do_perf_sw_event(PERF_TYPE_TRACEPOINT, event_id, count, 1,
+        /* Trace events already protected against recursion */
+        __do_perf_sw_event(PERF_TYPE_TRACEPOINT, event_id, count, 1,
                                 &data, regs);
 }
 EXPORT_SYMBOL_GPL(perf_tp_event);