Re: [PATCH 01/17] tools lib traceevent: Add state member to struct trace_seq

[Arnaldo Carvalho de Melo <acme@ghostprotocols.net>]

Em Wed, Jan 15, 2014 at 02:03:20PM +0900, Namhyung Kim escreveu:
> On Tue, 14 Jan 2014 21:56:55 -0500, Steven Rostedt wrote:
> > On Wed, 15 Jan 2014 11:49:28 +0900
> > Namhyung Kim <namhyung@kernel.org> wrote:
> >> Oh, it looks better.  But I'd like to TRACE_SEQ_CHECK() as is for some
> >> cases.  How about this?
> >
> > Looks good to me.
> >
> > Acked-by: Steven Rostedt <rostedt@goodmis.org>
> >
> > I'll try to look at the rest of the patches tomorrow.

Hi Steven, can I keep your ackd-by?
 
> Thanks, and I found that trace_seq_destroy() should use
> TRACE_SEQ_TRACE_RET instead.  Here's an updated patch.
> 
> Thanks,
> Namhyung
> 
> 
> From 539a5dd1cb3ba4cb03c283115a9a84f8e345514e Mon Sep 17 00:00:00 2001
> From: Namhyung Kim <namhyung@kernel.org>
> Date: Thu, 19 Dec 2013 18:17:44 +0900
> Subject: [PATCH] tools lib traceevent: Add state member to struct trace_seq
> 
> The trace_seq->state is for tracking errors during the use of
> trace_seq APIs and getting rid of die() in it.
> 
> Acked-by: Steven Rostedt <rostedt@goodmis.org>
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> ---
>  tools/lib/traceevent/Makefile      |  2 +-
>  tools/lib/traceevent/event-parse.h |  7 +++++
>  tools/lib/traceevent/trace-seq.c   | 55 +++++++++++++++++++++++++++++---------
>  3 files changed, 50 insertions(+), 14 deletions(-)
> 
> diff --git a/tools/lib/traceevent/Makefile b/tools/lib/traceevent/Makefile
> index f778d48ac609..56d52a33a3df 100644
> --- a/tools/lib/traceevent/Makefile
> +++ b/tools/lib/traceevent/Makefile
> @@ -136,7 +136,7 @@ export Q VERBOSE
>  
>  EVENT_PARSE_VERSION = $(EP_VERSION).$(EP_PATCHLEVEL).$(EP_EXTRAVERSION)
>  
> -INCLUDES = -I. $(CONFIG_INCLUDES)
> +INCLUDES = -I. -I $(srctree)/../../include $(CONFIG_INCLUDES)
>  
>  # Set compile option CFLAGS if not set elsewhere
>  CFLAGS ?= -g -Wall
> diff --git a/tools/lib/traceevent/event-parse.h b/tools/lib/traceevent/event-parse.h
> index cf5db9013f2c..3c890cb28db7 100644
> --- a/tools/lib/traceevent/event-parse.h
> +++ b/tools/lib/traceevent/event-parse.h
> @@ -58,6 +58,12 @@ struct pevent_record {
>  #endif
>  };
>  
> +enum trace_seq_fail {
> +	TRACE_SEQ__GOOD,
> +	TRACE_SEQ__BUFFER_POISONED,
> +	TRACE_SEQ__MEM_ALLOC_FAILED,
> +};
> +
>  /*
>   * 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).
> @@ -68,6 +74,7 @@ struct trace_seq {
>  	unsigned int		buffer_size;
>  	unsigned int		len;
>  	unsigned int		readpos;
> +	enum trace_seq_fail	state;
>  };
>  
>  void trace_seq_init(struct trace_seq *s);
> diff --git a/tools/lib/traceevent/trace-seq.c b/tools/lib/traceevent/trace-seq.c
> index d7f2e68bc5b9..f7112138e6af 100644
> --- a/tools/lib/traceevent/trace-seq.c
> +++ b/tools/lib/traceevent/trace-seq.c
> @@ -22,6 +22,7 @@
>  #include <string.h>
>  #include <stdarg.h>
>  
> +#include <asm/bug.h>
>  #include "event-parse.h"
>  #include "event-utils.h"
>  
> @@ -32,10 +33,21 @@
>  #define TRACE_SEQ_POISON	((void *)0xdeadbeef)
>  #define TRACE_SEQ_CHECK(s)						\
>  do {									\
> -	if ((s)->buffer == TRACE_SEQ_POISON)			\
> -		die("Usage of trace_seq after it was destroyed");	\
> +	if (WARN_ONCE((s)->buffer == TRACE_SEQ_POISON,			\
> +		      "Usage of trace_seq after it was destroyed"))	\
> +		(s)->state = TRACE_SEQ__BUFFER_POISONED;		\
>  } while (0)
>  
> +#define TRACE_SEQ_CHECK_RET_N(s, n)		\
> +do {						\
> +	TRACE_SEQ_CHECK(s);			\
> +	if ((s)->state != TRACE_SEQ__GOOD)	\
> +		return n; 			\
> +} while (0)
> +
> +#define TRACE_SEQ_CHECK_RET(s)   TRACE_SEQ_CHECK_RET_N(s, )
> +#define TRACE_SEQ_CHECK_RET0(s)  TRACE_SEQ_CHECK_RET_N(s, 0)
> +
>  /**
>   * trace_seq_init - initialize the trace_seq structure
>   * @s: a pointer to the trace_seq structure to initialize
> @@ -46,6 +58,7 @@ void trace_seq_init(struct trace_seq *s)
>  	s->readpos = 0;
>  	s->buffer_size = TRACE_SEQ_BUF_SIZE;
>  	s->buffer = malloc_or_die(s->buffer_size);
> +	s->state = TRACE_SEQ__GOOD;
>  }
>  
>  /**
> @@ -71,7 +84,7 @@ void trace_seq_destroy(struct trace_seq *s)
>  {
>  	if (!s)
>  		return;
> -	TRACE_SEQ_CHECK(s);
> +	TRACE_SEQ_CHECK_RET(s);
>  	free(s->buffer);
>  	s->buffer = TRACE_SEQ_POISON;
>  }
> @@ -80,8 +93,9 @@ static void expand_buffer(struct trace_seq *s)
>  {
>  	s->buffer_size += TRACE_SEQ_BUF_SIZE;
>  	s->buffer = realloc(s->buffer, s->buffer_size);
> -	if (!s->buffer)
> -		die("Can't allocate trace_seq buffer memory");
> +	if (WARN_ONCE(!s->buffer,
> +		      "Can't allocate trace_seq buffer memory"))
> +		s->state = TRACE_SEQ__MEM_ALLOC_FAILED;
>  }
>  
>  /**
> @@ -105,9 +119,9 @@ trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
>  	int len;
>  	int ret;
>  
> -	TRACE_SEQ_CHECK(s);
> -
>   try_again:
> +	TRACE_SEQ_CHECK_RET0(s);
> +
>  	len = (s->buffer_size - 1) - s->len;
>  
>  	va_start(ap, fmt);
> @@ -141,9 +155,9 @@ trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args)
>  	int len;
>  	int ret;
>  
> -	TRACE_SEQ_CHECK(s);
> -
>   try_again:
> +	TRACE_SEQ_CHECK_RET0(s);
> +
>  	len = (s->buffer_size - 1) - s->len;
>  
>  	ret = vsnprintf(s->buffer + s->len, len, fmt, args);
> @@ -172,13 +186,15 @@ int trace_seq_puts(struct trace_seq *s, const char *str)
>  {
>  	int len;
>  
> -	TRACE_SEQ_CHECK(s);
> +	TRACE_SEQ_CHECK_RET0(s);
>  
>  	len = strlen(str);
>  
>  	while (len > ((s->buffer_size - 1) - s->len))
>  		expand_buffer(s);
>  
> +	TRACE_SEQ_CHECK_RET0(s);
> +
>  	memcpy(s->buffer + s->len, str, len);
>  	s->len += len;
>  
> @@ -187,11 +203,13 @@ int trace_seq_puts(struct trace_seq *s, const char *str)
>  
>  int trace_seq_putc(struct trace_seq *s, unsigned char c)
>  {
> -	TRACE_SEQ_CHECK(s);
> +	TRACE_SEQ_CHECK_RET0(s);
>  
>  	while (s->len >= (s->buffer_size - 1))
>  		expand_buffer(s);
>  
> +	TRACE_SEQ_CHECK_RET0(s);
> +
>  	s->buffer[s->len++] = c;
>  
>  	return 1;
> @@ -199,7 +217,7 @@ int trace_seq_putc(struct trace_seq *s, unsigned char c)
>  
>  void trace_seq_terminate(struct trace_seq *s)
>  {
> -	TRACE_SEQ_CHECK(s);
> +	TRACE_SEQ_CHECK_RET(s);
>  
>  	/* There's always one character left on the buffer */
>  	s->buffer[s->len] = 0;
> @@ -208,5 +226,16 @@ void trace_seq_terminate(struct trace_seq *s)
>  int trace_seq_do_printf(struct trace_seq *s)
>  {
>  	TRACE_SEQ_CHECK(s);
> -	return printf("%.*s", s->len, s->buffer);
> +
> +	switch (s->state) {
> +	case TRACE_SEQ__GOOD:
> +		return printf("%.*s", s->len, s->buffer);
> +	case TRACE_SEQ__BUFFER_POISONED:
> +		puts("Usage of trace_seq after it was destroyed");
> +		break;
> +	case TRACE_SEQ__MEM_ALLOC_FAILED:
> +		puts("Can't allocate trace_seq buffer memory");
> +		break;
> +	}
> +	return -1;
>  }
> -- 
> 1.7.11.7