diff options
Diffstat (limited to 'kernel/trace/trace.h')
-rw-r--r-- | kernel/trace/trace.h | 32 |
1 files changed, 27 insertions, 5 deletions
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 12a82a7ad5a6..7150892c692a 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -478,6 +478,12 @@ enum { * can only be modified by current, we can reuse trace_recursion. */ TRACE_IRQ_BIT, + + /* + * When transitioning between context, the preempt_count() may + * not be correct. Allow for a single recursion to cover this case. + */ + TRACE_TRANSITION_BIT, }; #define trace_recursion_set(bit) do { (current)->trace_recursion |= (1<<(bit)); } while (0) @@ -522,14 +528,27 @@ static __always_inline int trace_test_and_set_recursion(int start, int max) return 0; bit = trace_get_context_bit() + start; - if (unlikely(val & (1 << bit))) - return -1; + if (unlikely(val & (1 << bit))) { + /* + * It could be that preempt_count has not been updated during + * a switch between contexts. Allow for a single recursion. + */ + bit = TRACE_TRANSITION_BIT; + if (trace_recursion_test(bit)) + return -1; + trace_recursion_set(bit); + barrier(); + return bit + 1; + } + + /* Normal check passed, clear the transition to allow it again */ + trace_recursion_clear(TRACE_TRANSITION_BIT); val |= 1 << bit; current->trace_recursion = val; barrier(); - return bit; + return bit + 1; } static __always_inline void trace_clear_recursion(int bit) @@ -539,6 +558,7 @@ static __always_inline void trace_clear_recursion(int bit) if (!bit) return; + bit--; bit = 1 << bit; val &= ~bit; @@ -636,13 +656,15 @@ void update_max_tr_single(struct trace_array *tr, #endif /* CONFIG_TRACER_MAX_TRACE */ #ifdef CONFIG_STACKTRACE -void ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags, +void ftrace_trace_userstack(struct trace_array *tr, + struct ring_buffer *buffer, unsigned long flags, int pc); void __trace_stack(struct trace_array *tr, unsigned long flags, int skip, int pc); #else -static inline void ftrace_trace_userstack(struct ring_buffer *buffer, +static inline void ftrace_trace_userstack(struct trace_array *tr, + struct ring_buffer *buffer, unsigned long flags, int pc) { } |