diff options
Diffstat (limited to 'kernel/trace/trace.h')
| -rw-r--r-- | kernel/trace/trace.h | 26 |
1 files changed, 23 insertions, 3 deletions
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 4055158c1dd2..fc3aa81a43e3 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -592,6 +592,12 @@ enum { * function is called to clear it. */ TRACE_GRAPH_NOTRACE_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) @@ -646,14 +652,27 @@ 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) @@ -663,6 +682,7 @@ static __always_inline void trace_clear_recursion(int bit) if (!bit) return; + bit--; bit = 1 << bit; val &= ~bit; |