[PATCH 0/4] tracing: couple of minor fixies

[PATCH 0/4] tracing: couple of minor fixies

[Jiri Olsa]

Hi,

sending few minor fixes.

1/4 - tracing: updating *ppos instead of filp->f_pos
2/4 - tracing: fix trace_seq_printf return value
3/4 - tracing: comment typo and documentation example fix
4/4 - tracing: removing cpu arg from rb_time_stamp function

wbr,
jirka

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
---
 Documentation/trace/ftrace.txt |    2 ++
 include/linux/trace_seq.h      |    2 +-
 kernel/trace/ftrace.c          |    2 +-
 kernel/trace/ring_buffer.c     |   12 ++++++------
 kernel/trace/trace.c           |    8 ++++----
 kernel/trace/trace_output.c    |    2 +-
 6 files changed, 15 insertions(+), 13 deletions(-)

[PATCH 1/4] tracing: updating *ppos instead of filp->f_pos

[Jiri Olsa]

Instead of direct updating filp->f_pos we should update *ppos argument.
The filp->f_pos gets updated within the file_pos_write function called
from sys_write.

wbr,
jirka

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
---
 kernel/trace/ftrace.c |    2 +-
 kernel/trace/trace.c  |    8 ++++----
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index b10c0d9..1ed514f 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -751,7 +751,7 @@ ftrace_profile_write(struct file *filp, const char __user *ubuf,
  out:
 	mutex_unlock(&ftrace_profile_lock);
 
-	filp->f_pos += cnt;
+	*ppos += cnt;
 
 	return cnt;
 }
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 026e715..9d3067a 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2440,7 +2440,7 @@ tracing_trace_options_write(struct file *filp, const char __user *ubuf,
 			return ret;
 	}
 
-	filp->f_pos += cnt;
+	*ppos += cnt;
 
 	return cnt;
 }
@@ -2582,7 +2582,7 @@ tracing_ctrl_write(struct file *filp, const char __user *ubuf,
 	}
 	mutex_unlock(&trace_types_lock);
 
-	filp->f_pos += cnt;
+	*ppos += cnt;
 
 	return cnt;
 }
@@ -2764,7 +2764,7 @@ tracing_set_trace_write(struct file *filp, const char __user *ubuf,
 	if (err)
 		return err;
 
-	filp->f_pos += ret;
+	*ppos += ret;
 
 	return ret;
 }
@@ -3299,7 +3299,7 @@ tracing_entries_write(struct file *filp, const char __user *ubuf,
 		}
 	}
 
-	filp->f_pos += cnt;
+	*ppos += cnt;
 
 	/* If check pages failed, return ENOMEM */
 	if (tracing_disabled)
-- 
1.6.2.5

[PATCH 2/4] tracing: fix trace_seq_printf return value

[Jiri Olsa]

I believe we want to return the number of written characters,
instead of the available buffer length.

wbr,
jirka

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
---
 kernel/trace/trace_output.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index ed17565..e871125 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -95,7 +95,7 @@ trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
 
 	s->len += ret;
 
-	return len;
+	return ret;
 }
 EXPORT_SYMBOL_GPL(trace_seq_printf);
 
-- 
1.6.2.5

[PATCH 3/4] tracing: comment typo and documentation example fix

[Jiri Olsa]

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
---
 Documentation/trace/ftrace.txt |    2 ++
 kernel/trace/ring_buffer.c     |    2 +-
 2 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt
index 957b22f..8179692 100644
--- a/Documentation/trace/ftrace.txt
+++ b/Documentation/trace/ftrace.txt
@@ -1231,6 +1231,7 @@ something like this simple program:
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <unistd.h>
+#include <string.h>
 
 #define _STR(x) #x
 #define STR(x) _STR(x)
@@ -1265,6 +1266,7 @@ const char *find_debugfs(void)
                return NULL;
        }
 
+       strcat(debugfs, "/tracing/");
        debugfs_found = 1;
 
        return debugfs;
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index e43c928..d33e5ca 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -2684,7 +2684,7 @@ unsigned long ring_buffer_entries(struct ring_buffer *buffer)
 EXPORT_SYMBOL_GPL(ring_buffer_entries);
 
 /**
- * ring_buffer_overrun_cpu - get the number of overruns in buffer
+ * ring_buffer_overruns - get the number of overruns in buffer
  * @buffer: The ring buffer
  *
  * Returns the total number of overruns in the ring buffer
-- 
1.6.2.5

[PATCH 4/4] tracing: removing cpu arg from rb_time_stamp function

[Jiri Olsa]

The cpu argument is not used inside rb_time_stamp function. Plus typo fix.

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
---
 include/linux/trace_seq.h  |    2 +-
 kernel/trace/ring_buffer.c |   10 +++++-----
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/include/linux/trace_seq.h b/include/linux/trace_seq.h
index c134dd1..09077f6 100644
--- a/include/linux/trace_seq.h
+++ b/include/linux/trace_seq.h
@@ -7,7 +7,7 @@
 
 /*
  * Trace sequences are used to allow a function to call several other functions
- * to create a string of data to use (up to a max of PAGE_SIZE.
+ * to create a string of data to use (up to a max of PAGE_SIZE).
  */
 
 struct trace_seq {
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index d33e5ca..63446f1 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -486,7 +486,7 @@ struct ring_buffer_iter {
 /* Up this if you want to test the TIME_EXTENTS and normalization */
 #define DEBUG_SHIFT 0
 
-static inline u64 rb_time_stamp(struct ring_buffer *buffer, int cpu)
+static inline u64 rb_time_stamp(struct ring_buffer *buffer)
 {
 	/* shift to debug/test normalization and TIME_EXTENTS */
 	return buffer->clock() << DEBUG_SHIFT;
@@ -497,7 +497,7 @@ u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu)
 	u64 time;
 
 	preempt_disable_notrace();
-	time = rb_time_stamp(buffer, cpu);
+	time = rb_time_stamp(buffer);
 	preempt_enable_no_resched_notrace();
 
 	return time;
@@ -602,7 +602,7 @@ static struct list_head *rb_list_head(struct list_head *list)
 }
 
 /*
- * rb_is_head_page - test if the give page is the head page
+ * rb_is_head_page - test if the given page is the head page
  *
  * Because the reader may move the head_page pointer, we can
  * not trust what the head page is (it may be pointing to
@@ -1871,7 +1871,7 @@ rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer,
 		 * Nested commits always have zero deltas, so
 		 * just reread the time stamp
 		 */
-		*ts = rb_time_stamp(buffer, cpu_buffer->cpu);
+		*ts = rb_time_stamp(buffer);
 		next_page->page->time_stamp = *ts;
 	}
 
@@ -2114,7 +2114,7 @@ rb_reserve_next_event(struct ring_buffer *buffer,
 	if (RB_WARN_ON(cpu_buffer, ++nr_loops > 1000))
 		goto out_fail;
 
-	ts = rb_time_stamp(cpu_buffer->buffer, cpu_buffer->cpu);
+	ts = rb_time_stamp(cpu_buffer->buffer);
 
 	/*
 	 * Only the first commit can update the timestamp.
-- 
1.6.2.5

Re: [PATCH 2/4] tracing: fix trace_seq_printf return value

[Steven Rostedt]

On Wed, 2009-10-21 at 16:36 +0200, Jiri Olsa wrote:
> I believe we want to return the number of written characters,
> instead of the available buffer length.
> 
> wbr,
> jirka
> 
> Signed-off-by: Jiri Olsa <jolsa@redhat.com>
> ---
>  kernel/trace/trace_output.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
> index ed17565..e871125 100644
> --- a/kernel/trace/trace_output.c
> +++ b/kernel/trace/trace_output.c
> @@ -95,7 +95,7 @@ trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
>  
>  	s->len += ret;
>  
> -	return len;
> +	return ret;

Actually the return value here is ambiguous. Returning len is actually
safer. It probably should only return 0 (buffer not big enough to write
to) or 1 (buffer is big enough).

Because this should actually return non zero:

  trace_seq_printf(s, "");

-- Steve

>  }
>  EXPORT_SYMBOL_GPL(trace_seq_printf);
>  

Re: [PATCH 4/4] tracing: removing cpu arg from rb_time_stamp function

[Steven Rostedt]

On Wed, 2009-10-21 at 16:36 +0200, Jiri Olsa wrote:
> The cpu argument is not used inside rb_time_stamp function. Plus typo fix.
> 
> Signed-off-by: Jiri Olsa <jolsa@redhat.com>
> ---
>  include/linux/trace_seq.h  |    2 +-
>  kernel/trace/ring_buffer.c |   10 +++++-----
>  2 files changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/include/linux/trace_seq.h b/include/linux/trace_seq.h
> index c134dd1..09077f6 100644
> --- a/include/linux/trace_seq.h
> +++ b/include/linux/trace_seq.h
> @@ -7,7 +7,7 @@
>  
>  /*
>   * Trace sequences are used to allow a function to call several other functions
> - * to create a string of data to use (up to a max of PAGE_SIZE.
> + * to create a string of data to use (up to a max of PAGE_SIZE).
>   */
>  
>  struct trace_seq {
> diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
> index d33e5ca..63446f1 100644
> --- a/kernel/trace/ring_buffer.c
> +++ b/kernel/trace/ring_buffer.c
> @@ -486,7 +486,7 @@ struct ring_buffer_iter {
>  /* Up this if you want to test the TIME_EXTENTS and normalization */
>  #define DEBUG_SHIFT 0
>  
> -static inline u64 rb_time_stamp(struct ring_buffer *buffer, int cpu)
> +static inline u64 rb_time_stamp(struct ring_buffer *buffer)
>  {
>  	/* shift to debug/test normalization and TIME_EXTENTS */
>  	return buffer->clock() << DEBUG_SHIFT;
> @@ -497,7 +497,7 @@ u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu)
>  	u64 time;
>  
>  	preempt_disable_notrace();
> -	time = rb_time_stamp(buffer, cpu);
> +	time = rb_time_stamp(buffer);

Yeah, originally this was to deal with cpu_clock() which takes cpu as
its parameter. But we now just call "raw_smp_processor_id" instead
directly when using cpu_clock.

Thanks,

-- Steve

>  	preempt_enable_no_resched_notrace();
>  
>  	return time;
> @@ -602,7 +602,7 @@ static struct list_head *rb_list_head(struct list_head *list)
>  }
>  

Re: [PATCH 0/4] tracing: couple of minor fixies

[Steven Rostedt]

On Wed, 2009-10-21 at 16:36 +0200, Jiri Olsa wrote:
> Hi,
> 
> sending few minor fixes.
> 
> 1/4 - tracing: updating *ppos instead of filp->f_pos
> 2/4 - tracing: fix trace_seq_printf return value
> 3/4 - tracing: comment typo and documentation example fix
> 4/4 - tracing: removing cpu arg from rb_time_stamp function

Thanks,

I'll take 1,3 and 4. As 2 we should change it to return 0 or 1 and add a
comment to the use of it.

-- Steve

Re: [PATCH 2/4] tracing: fix trace_seq_printf return value

[Jiri Olsa]

On Wed, Oct 21, 2009 at 12:20:35PM -0400, Steven Rostedt wrote:
> On Wed, 2009-10-21 at 16:36 +0200, Jiri Olsa wrote:
> > I believe we want to return the number of written characters,
> > instead of the available buffer length.
> > 
> > wbr,
> > jirka
> > 
> > Signed-off-by: Jiri Olsa <jolsa@redhat.com>
> > ---
> >  kernel/trace/trace_output.c |    2 +-
> >  1 files changed, 1 insertions(+), 1 deletions(-)
> > 
> > diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
> > index ed17565..e871125 100644
> > --- a/kernel/trace/trace_output.c
> > +++ b/kernel/trace/trace_output.c
> > @@ -95,7 +95,7 @@ trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
> >  
> >  	s->len += ret;
> >  
> > -	return len;
> > +	return ret;
> 
> Actually the return value here is ambiguous. Returning len is actually
> safer. It probably should only return 0 (buffer not big enough to write
> to) or 1 (buffer is big enough).
> 
> Because this should actually return non zero:
> 
>   trace_seq_printf(s, "");
> 
> -- Steve
> 
> >  }
> >  EXPORT_SYMBOL_GPL(trace_seq_printf);
> >  
>

I made the suggested fix, plus spot not used function.

---
Making trace_seq_printf return 0 if the trace oversizes the buffer's free
space, 1 otherwise.  Removing not used trace_seq_vprintf function.

wbr,
jirka

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
---
 include/linux/trace_seq.h   |    2 --
 kernel/trace/trace_output.c |   37 ++++---------------------------------
 2 files changed, 4 insertions(+), 35 deletions(-)

diff --git a/include/linux/trace_seq.h b/include/linux/trace_seq.h
index c134dd1..6fc4651 100644
--- a/include/linux/trace_seq.h
+++ b/include/linux/trace_seq.h
@@ -29,8 +29,6 @@ trace_seq_init(struct trace_seq *s)
 #ifdef CONFIG_TRACING
 extern int trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
 	__attribute__ ((format (printf, 2, 3)));
-extern int trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args)
-	__attribute__ ((format (printf, 2, 0)));
 extern int
 trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary);
 extern void trace_print_seq(struct seq_file *m, struct trace_seq *s);
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index ed17565..11bd0e5 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -69,6 +69,9 @@ enum print_line_t trace_print_printk_msg_only(struct trace_iterator *iter)
  * @s: trace sequence descriptor
  * @fmt: printf format string
  *
+ * It returns 0 if the trace oversizes the buffer's free
+ * space, 1 otherwise.
+ *
  * The tracer may use either sequence operations or its own
  * copy to user routines. To simplify formating of a trace
  * trace_seq_printf is used to store strings into a special
@@ -95,42 +98,10 @@ trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
 
 	s->len += ret;
 
-	return len;
+	return 1;
 }
 EXPORT_SYMBOL_GPL(trace_seq_printf);
 
-/**
- * trace_seq_vprintf - sequence printing of trace information
- * @s: trace sequence descriptor
- * @fmt: printf format string
- *
- * The tracer may use either sequence operations or its own
- * copy to user routines. To simplify formating of a trace
- * trace_seq_printf is used to store strings into a special
- * buffer (@s). Then the output may be either used by
- * the sequencer or pulled into another buffer.
- */
-int
-trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args)
-{
-	int len = (PAGE_SIZE - 1) - s->len;
-	int ret;
-
-	if (!len)
-		return 0;
-
-	ret = vsnprintf(s->buffer + s->len, len, fmt, args);
-
-	/* If we can't write it all, don't bother writing anything */
-	if (ret >= len)
-		return 0;
-
-	s->len += ret;
-
-	return len;
-}
-EXPORT_SYMBOL_GPL(trace_seq_vprintf);
-
 int trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary)
 {
 	int len = (PAGE_SIZE - 1) - s->len;
 

Re: [PATCH 2/4] tracing: fix trace_seq_printf return value

[Steven Rostedt]

On Thu, 2009-10-22 at 00:02 +0200, Jiri Olsa wrote:
> On Wed, Oct 21, 2009 at 12:20:35PM -0400, Steven Rostedt wrote:
> > On Wed, 2009-10-21 at 16:36 +0200, Jiri Olsa wrote:
> > > I believe we want to return the number of written characters,
> > > instead of the available buffer length.
> > > 
> > > wbr,
> > > jirka
> > > 
> > > Signed-off-by: Jiri Olsa <jolsa@redhat.com>
> > > ---
> > >  kernel/trace/trace_output.c |    2 +-
> > >  1 files changed, 1 insertions(+), 1 deletions(-)
> > > 
> > > diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
> > > index ed17565..e871125 100644
> > > --- a/kernel/trace/trace_output.c
> > > +++ b/kernel/trace/trace_output.c
> > > @@ -95,7 +95,7 @@ trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
> > >  
> > >  	s->len += ret;
> > >  
> > > -	return len;
> > > +	return ret;
> > 
> > Actually the return value here is ambiguous. Returning len is actually
> > safer. It probably should only return 0 (buffer not big enough to write
> > to) or 1 (buffer is big enough).
> > 
> > Because this should actually return non zero:
> > 
> >   trace_seq_printf(s, "");
> > 
> > -- Steve
> > 
> > >  }
> > >  EXPORT_SYMBOL_GPL(trace_seq_printf);
> > >  
> >
> 
> I made the suggested fix, plus spot not used function.
> 
> ---
> Making trace_seq_printf return 0 if the trace oversizes the buffer's free
> space, 1 otherwise.  Removing not used trace_seq_vprintf function.

err, I hate to remove that function. This is a utility file that is
exported for other parts of the kernel to use. At least make that a
separate patch.

-- Steve

Re: [PATCH 2/4] tracing: fix trace_seq_printf return value

[Jiri Olsa]

On Wed, Oct 21, 2009 at 06:14:07PM -0400, Steven Rostedt wrote:
> On Thu, 2009-10-22 at 00:02 +0200, Jiri Olsa wrote:
> > On Wed, Oct 21, 2009 at 12:20:35PM -0400, Steven Rostedt wrote:
> > > On Wed, 2009-10-21 at 16:36 +0200, Jiri Olsa wrote:
> > > > I believe we want to return the number of written characters,
> > > > instead of the available buffer length.
> > > > 
> > > > wbr,
> > > > jirka
> > > > 
> > > > Signed-off-by: Jiri Olsa <jolsa@redhat.com>
> > > > ---
> > > >  kernel/trace/trace_output.c |    2 +-
> > > >  1 files changed, 1 insertions(+), 1 deletions(-)
> > > > 
> > > > diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
> > > > index ed17565..e871125 100644
> > > > --- a/kernel/trace/trace_output.c
> > > > +++ b/kernel/trace/trace_output.c
> > > > @@ -95,7 +95,7 @@ trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
> > > >  
> > > >  	s->len += ret;
> > > >  
> > > > -	return len;
> > > > +	return ret;
> > > 
> > > Actually the return value here is ambiguous. Returning len is actually
> > > safer. It probably should only return 0 (buffer not big enough to write
> > > to) or 1 (buffer is big enough).
> > > 
> > > Because this should actually return non zero:
> > > 
> > >   trace_seq_printf(s, "");
> > > 
> > > -- Steve
> > > 
> > > >  }
> > > >  EXPORT_SYMBOL_GPL(trace_seq_printf);
> > > >  
> > >
> > 
> > I made the suggested fix, plus spot not used function.
> > 
> > ---
> > Making trace_seq_printf return 0 if the trace oversizes the buffer's free
> > space, 1 otherwise.  Removing not used trace_seq_vprintf function.
> 
> err, I hate to remove that function. This is a utility file that is
> exported for other parts of the kernel to use. At least make that a
> separate patch.
np, sending out just the first part

jirka

---

Making trace_seq_printf return 0 if the trace oversizes the buffer's free
space, 1 otherwise.

wbr,
jirka

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
---
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index ed17565..b6c12c6 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -69,6 +69,9 @@ enum print_line_t trace_print_printk_msg_only(struct trace_iterator *iter)
  * @s: trace sequence descriptor
  * @fmt: printf format string
  *
+ * It returns 0 if the trace oversizes the buffer's free
+ * space, 1 otherwise.
+ *
  * The tracer may use either sequence operations or its own
  * copy to user routines. To simplify formating of a trace
  * trace_seq_printf is used to store strings into a special
@@ -95,7 +98,7 @@ trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
 
 	s->len += ret;
 
-	return len;
+	return 1;
 }
 EXPORT_SYMBOL_GPL(trace_seq_printf);
 

Re: [PATCH 2/4] tracing: fix trace_seq_printf return value

[Steven Rostedt]

On Thu, 2009-10-22 at 14:09 +0200, Jiri Olsa wrote:

> > err, I hate to remove that function. This is a utility file that is
> > exported for other parts of the kernel to use. At least make that a
> > separate patch.
> np, sending out just the first part

Thanks, I'll pull you patches in today and queue them up for 2.6.33.

-- Steve