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Commit e4a3f541 authored by Steven Rostedt's avatar Steven Rostedt Committed by Steven Rostedt
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tracing: Still trace filtered irq functions when irq trace is disabled 



If a function is set to be traced by the set_graph_function, but the
option funcgraph-irqs is zero, and the traced function happens to be
called from a interrupt, it will not be traced.

The point of funcgraph-irqs is to not trace interrupts when we are
preempted by an irq, not to not trace functions we want to trace that
happen to be *in* a irq.

Luckily the current->trace_recursion element is perfect to add a flag
to help us be able to trace functions within an interrupt even when
we are not tracing interrupts that preempt the trace.

Reported-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Tested-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent e08fbb78

kernel/trace/trace.h

+34 −16
Original line number Diff line number Diff line
@@ -278,6 +278,29 @@ struct tracer { 
};





/* Only current can touch trace_recursion */

#define trace_recursion_inc() do { (current)->trace_recursion++; } while (0)

#define trace_recursion_dec() do { (current)->trace_recursion--; } while (0)



/* Ring buffer has the 10 LSB bits to count */

#define trace_recursion_buffer() ((current)->trace_recursion & 0x3ff)



/* for function tracing recursion */

#define TRACE_INTERNAL_BIT		(1<<11)

#define TRACE_GLOBAL_BIT		(1<<12)

/*

 * Abuse of the trace_recursion.

 * As we need a way to maintain state if we are tracing the function

 * graph in irq because we want to trace a particular function that

 * was called in irq context but we have irq tracing off. Since this

 * can only be modified by current, we can reuse trace_recursion.

 */

#define TRACE_IRQ_BIT			(1<<13)



#define trace_recursion_set(bit)	do { (current)->trace_recursion |= (bit); } while (0)

#define trace_recursion_clear(bit)	do { (current)->trace_recursion &= ~(bit); } while (0)

#define trace_recursion_test(bit)	((current)->trace_recursion & (bit))



#define TRACE_PIPE_ALL_CPU	-1



int tracer_init(struct tracer *t, struct trace_array *tr);
@@ -516,9 +539,19 @@ static inline int ftrace_graph_addr(unsigned long addr) 
		return 1;



	for (i = 0; i < ftrace_graph_count; i++) {

		if (addr == ftrace_graph_funcs[i])

		if (addr == ftrace_graph_funcs[i]) {

			/*

			 * If no irqs are to be traced, but a set_graph_function

			 * is set, and called by an interrupt handler, we still

			 * want to trace it.

			 */

			if (in_irq())

				trace_recursion_set(TRACE_IRQ_BIT);

			else

				trace_recursion_clear(TRACE_IRQ_BIT);

			return 1;

		}

	}



	return 0;

}
@@ -794,19 +827,4 @@ extern const char *__stop___trace_bprintk_fmt[]; 
	FTRACE_ENTRY(call, struct_name, id, PARAMS(tstruct), PARAMS(print))

#include "trace_entries.h"



/* Only current can touch trace_recursion */

#define trace_recursion_inc() do { (current)->trace_recursion++; } while (0)

#define trace_recursion_dec() do { (current)->trace_recursion--; } while (0)



/* Ring buffer has the 10 LSB bits to count */

#define trace_recursion_buffer() ((current)->trace_recursion & 0x3ff)



/* for function tracing recursion */

#define TRACE_INTERNAL_BIT		(1<<11)

#define TRACE_GLOBAL_BIT		(1<<12)



#define trace_recursion_set(bit)	do { (current)->trace_recursion |= (bit); } while (0)

#define trace_recursion_clear(bit)	do { (current)->trace_recursion &= ~(bit); } while (0)

#define trace_recursion_test(bit)	((current)->trace_recursion & (bit))



#endif /* _LINUX_KERNEL_TRACE_H */

kernel/trace/trace_functions_graph.c

+1 −1
Original line number Diff line number Diff line
@@ -227,7 +227,7 @@ int __trace_graph_entry(struct trace_array *tr, 


static inline int ftrace_graph_ignore_irqs(void)

{

	if (!ftrace_graph_skip_irqs)

	if (!ftrace_graph_skip_irqs || trace_recursion_test(TRACE_IRQ_BIT))

		return 0;



	return in_irq();