linux-kernel - Re: [PATCH] tracing/filters: use ring_buffer_discard_commit() in filter_check

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Date:	Wed, 08 Apr 2009 03:14:01 -0500
From:	Tom Zanussi <tzanussi@...il.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	linux-kernel <linux-kernel@...r.kernel.org>,
	Steven Rostedt <rostedt@...dmis.org>, fweisbec@...il.com
Subject: Re: [PATCH] tracing/filters: use ring_buffer_discard_commit() in
 filter_check_discard()

On Tue, 2009-04-07 at 15:08 +0200, Ingo Molnar wrote:
> * Tom Zanussi <tzanussi@...il.com> wrote:
> 
> > This patch changes filter_check_discard() to make use of the new 
> > ring_buffer_discard_commit() function and modifies the current 
> > users to call the old commit function in the non-discard case.  It 
> > also introduces a version of filter_check_discard() that uses the 
> > global trace buffer (filter_current_check_discard()) for those 
> > cases.
> 
> Nice!
> 
> I've merged it into tip/tracing/filters but it cannot go into 
> tip/master yet due to build failures. I fixed the obvious typo 
> problem (find the fix below) but punted on this one for now:
> 
>  kernel/built-in.o: In function `filter_check_discard':
>  trace.c:(.text+0x613fc): undefined reference to  `filter_match_preds'
>  kernel/built-in.o: In function `trace_vprintk':
>  (.text+0x6154f): undefined reference to `event_print'
>  kernel/built-in.o: In function `trace_vbprintk':
>  (.text+0x61717): undefined reference to `event_bprint'
>  kernel/built-in.o: In function `__ftrace_trace_stack':
> 
> config attached.
> 
> 	Ingo
> 
> Index: linux/kernel/trace/trace_branch.c
> ===================================================================
> --- linux.orig/kernel/trace/trace_branch.c
> +++ linux/kernel/trace/trace_branch.c
> @@ -74,7 +74,7 @@ probe_likely_condition(struct ftrace_bra
>  	entry->line = f->line;
>  	entry->correct = val == expect;
>  
> -	if !(filter_check_discard(call, entry, event))
> +	if (!(filter_check_discard(call, entry, tr->buffer, event)))
>  		ring_buffer_unlock_commit(tr->buffer, event);
>  
>   out:
> 

Wow, I can't believe I missed that - didn't have CONFIG_BRANCH_TRACE on
I guess.

As for the other errors, it's the CONFIG_EVENT_TRACER not being turned
on again.  I think the tracing config patch below would be a better
solution than the one I previously posted...

It adds a new config option, CONFIG_EVENT_TRACING that gets selected
when CONFIG_TRACING is selected and adds everything needed by the stuff
in trace_export - basically all the event tracing support needed by e.g.
bprint, minus the actual events, which are only included if
CONFIG_EVENT_TRACER is selected.  So CONFIG_EVENT_TRACER can be used to
turn on or off the generated events (what I think of as the 'event
tracer'), while CONFIG_EVENT_TRACING turns on or off the base event
tracing support used by both the event tracer and the other things such
as bprint that can't be configured out. 

Signed-off-by: Tom Zanussi <tzanussi@...il.com>

---
 include/asm-generic/vmlinux.lds.h |    2 +-
 kernel/trace/Kconfig              |    4 ++++
 kernel/trace/Makefile             |    6 +++---
 3 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 7fa660f..7e9b1e9 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -61,7 +61,7 @@
 #define BRANCH_PROFILE()
 #endif
 
-#ifdef CONFIG_EVENT_TRACER
+#ifdef CONFIG_EVENT_TRACING
 #define FTRACE_EVENTS()	VMLINUX_SYMBOL(__start_ftrace_events) = .;	\
 			*(_ftrace_events)				\
 			VMLINUX_SYMBOL(__stop_ftrace_events) = .;
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 23b96eb..644606e 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -48,6 +48,9 @@ config FTRACE_NMI_ENTER
        depends on HAVE_FTRACE_NMI_ENTER
        default y
 
+config EVENT_TRACING
+	bool
+
 config TRACING
 	bool
 	select DEBUG_FS
@@ -56,6 +59,7 @@ config TRACING
 	select TRACEPOINTS
 	select NOP_TRACER
 	select BINARY_PRINTF
+	select EVENT_TRACING
 
 #
 # Minimum requirements an architecture has to meet for us to
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index 2630f51..3ad367e 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -40,11 +40,11 @@ obj-$(CONFIG_POWER_TRACER) += trace_power.o
 obj-$(CONFIG_KMEMTRACE) += kmemtrace.o
 obj-$(CONFIG_WORKQUEUE_TRACER) += trace_workqueue.o
 obj-$(CONFIG_BLK_DEV_IO_TRACE)	+= blktrace.o
-obj-$(CONFIG_EVENT_TRACER) += trace_events.o
+obj-$(CONFIG_EVENT_TRACING) += trace_events.o
 obj-$(CONFIG_EVENT_TRACER) += events.o
-obj-$(CONFIG_EVENT_TRACER) += trace_export.o
+obj-$(CONFIG_EVENT_TRACING) += trace_export.o
 obj-$(CONFIG_FTRACE_SYSCALLS) += trace_syscalls.o
 obj-$(CONFIG_EVENT_PROFILE) += trace_event_profile.o
-obj-$(CONFIG_EVENT_TRACER) += trace_events_filter.o
+obj-$(CONFIG_EVENT_TRACING) += trace_events_filter.o
 
 libftrace-y := ftrace.o
-- 
1.5.6.3



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