diff options
Diffstat (limited to 'include/linux/trace_recursion.h')
| -rw-r--r-- | include/linux/trace_recursion.h | 27 |
1 files changed, 18 insertions, 9 deletions
diff --git a/include/linux/trace_recursion.h b/include/linux/trace_recursion.h index fe95f0922526..c303f7a114e9 100644 --- a/include/linux/trace_recursion.h +++ b/include/linux/trace_recursion.h @@ -116,13 +116,9 @@ enum { static __always_inline int trace_get_context_bit(void) { - unsigned long pc = preempt_count(); + unsigned char bit = interrupt_context_level(); - if (!(pc & (NMI_MASK | HARDIRQ_MASK | SOFTIRQ_OFFSET))) - return TRACE_CTX_NORMAL; - else - return pc & NMI_MASK ? TRACE_CTX_NMI : - pc & HARDIRQ_MASK ? TRACE_CTX_IRQ : TRACE_CTX_SOFTIRQ; + return TRACE_CTX_NORMAL - bit; } #ifdef CONFIG_FTRACE_RECORD_RECURSION @@ -139,6 +135,9 @@ extern void ftrace_record_recursion(unsigned long ip, unsigned long parent_ip); # define do_ftrace_record_recursion(ip, pip) do { } while (0) #endif +/* + * Preemption is promised to be disabled when return bit >= 0. + */ static __always_inline int trace_test_and_set_recursion(unsigned long ip, unsigned long pip, int start) { @@ -148,8 +147,12 @@ static __always_inline int trace_test_and_set_recursion(unsigned long ip, unsign bit = trace_get_context_bit() + start; 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. + * If an interrupt occurs during a trace, and another trace + * happens in that interrupt but before the preempt_count is + * updated to reflect the new interrupt context, then this + * will think a recursion occurred, and the event will be dropped. + * Let a single instance happen via the TRANSITION_BIT to + * not drop those events. */ bit = TRACE_CTX_TRANSITION + start; if (val & (1 << bit)) { @@ -162,11 +165,17 @@ static __always_inline int trace_test_and_set_recursion(unsigned long ip, unsign current->trace_recursion = val; barrier(); + preempt_disable_notrace(); + return bit; } +/* + * Preemption will be enabled (if it was previously enabled). + */ static __always_inline void trace_clear_recursion(int bit) { + preempt_enable_notrace(); barrier(); trace_recursion_clear(bit); } @@ -178,7 +187,7 @@ static __always_inline void trace_clear_recursion(int bit) * tracing recursed in the same context (normal vs interrupt), * * Returns: -1 if a recursion happened. - * >= 0 if no recursion + * >= 0 if no recursion. */ static __always_inline int ftrace_test_recursion_trylock(unsigned long ip, unsigned long parent_ip) |