sched/core: Fix a race between try_to_wake_up() and a woken up task

[GitHub/mt8127/android_kernel_alcatel_ttab.git] / kernel / trace / trace_branch.c

diff --git a/kernel/trace/trace_branch.c b/kernel/trace/trace_branch.c
index d594da0dc03ce53db530e238df1d410c4b89e29a..cb89197adf5c4e344a9d03f3b6df47fae6e03a66 100644 (file)
--- a/kernel/trace/trace_branch.c
+++ b/kernel/trace/trace_branch.c
@@ -37,9 +37,12 @@ probe_likely_condition(struct ftrace_branch_data *f, int val, int expect)
        struct trace_branch *entry;
        struct ring_buffer *buffer;
        unsigned long flags;
-       int cpu, pc;
+       int pc;
        const char *p;
 
+       if (current->trace_recursion & TRACE_BRANCH_BIT)
+               return;
+
        /*
         * I would love to save just the ftrace_likely_data pointer, but
         * this code can also be used by modules. Ugly things can happen
@@ -50,10 +53,10 @@ probe_likely_condition(struct ftrace_branch_data *f, int val, int expect)
        if (unlikely(!tr))
                return;
 
-       local_irq_save(flags);
-       cpu = raw_smp_processor_id();
-       data = per_cpu_ptr(tr->trace_buffer.data, cpu);
-       if (atomic_inc_return(&data->disabled) != 1)
+       raw_local_irq_save(flags);
+       current->trace_recursion |= TRACE_BRANCH_BIT;
+       data = this_cpu_ptr(tr->trace_buffer.data);
+       if (atomic_read(&data->disabled))
                goto out;
 
        pc = preempt_count();
@@ -82,8 +85,8 @@ probe_likely_condition(struct ftrace_branch_data *f, int val, int expect)
                __buffer_unlock_commit(buffer, event);
 
  out:
-       atomic_dec(&data->disabled);
-       local_irq_restore(flags);
+       current->trace_recursion &= ~TRACE_BRANCH_BIT;
+       raw_local_irq_restore(flags);
 }
 
 static inline