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tracing: Still trace filtered irq functions when irq trace is disabled

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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: Heiko Carstens <heiko.carstens@de.ibm.com>
Tested-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt 2011-06-14 19:02:29 -04:00 committed by Steven Rostedt
parent e08fbb78f0
commit e4a3f541f0
2 changed files with 35 additions and 17 deletions
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50
kernel/trace/trace.h
View File

@ -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);
@ -516,8 +539,18 @@ 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 */

2
kernel/trace/trace_functions_graph.c
View File

@ -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();