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tracing: Add internal ftrace trace_puts() for ftrace to use 

There's a few places that ftrace uses trace_printk() for internal
use, but this requires context (normal, softirq, irq, NMI) buffers
to keep things lockless. But the trace_puts() does not, as it can
write the string directly into the ring buffer. Make a internal helper
for trace_puts() and have the internal functions use that.

This way the extra context buffers are not used.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (Red Hat) 2013-03-09 00:40:58 -05:00 committed by Steven Rostedt
parent 9d3c752c06
commit ca268da6e4
2 changed files with 15 additions and 4 deletions
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8
kernel/trace/trace.c
View File

@ -443,16 +443,16 @@ void tracing_snapshot(void)
unsigned long flags;
if (!tr->allocated_snapshot) {
trace_printk("*** SNAPSHOT NOT ALLOCATED ***\n");
trace_printk("*** stopping trace here! ***\n");
internal_trace_puts("*** SNAPSHOT NOT ALLOCATED ***\n");
internal_trace_puts("*** stopping trace here! ***\n");
tracing_off();
return;
}
/* Note, snapshot can not be used when the tracer uses it */
if (tracer->use_max_tr) {
trace_printk("*** LATENCY TRACER ACTIVE ***\n");
trace_printk("*** Can not use snapshot (sorry) ***\n");
internal_trace_puts("*** LATENCY TRACER ACTIVE ***\n");
internal_trace_puts("*** Can not use snapshot (sorry) ***\n");
return;
}

11
kernel/trace/trace.h
View File

@ -1040,6 +1040,17 @@ void trace_printk_start_comm(void);
int trace_keep_overwrite(struct tracer *tracer, u32 mask, int set);
int set_tracer_flag(struct trace_array *tr, unsigned int mask, int enabled);
/*
* Normal trace_printk() and friends allocates special buffers
* to do the manipulation, as well as saves the print formats
* into sections to display. But the trace infrastructure wants
* to use these without the added overhead at the price of being
* a bit slower (used mainly for warnings, where we don't care
* about performance). The internal_trace_puts() is for such
* a purpose.
*/
#define internal_trace_puts(str) __trace_puts(_THIS_IP_, str, strlen(str))
#undef FTRACE_ENTRY
#define FTRACE_ENTRY(call, struct_name, id, tstruct, print, filter) \
extern struct ftrace_event_call \