Re: [RFC][PATCH 04/12 v3] tracing: Convert seq_buf_path() to be like seq_path()

[Petr Mladek]

On Tue 2014-11-04 10:52:41, Steven Rostedt wrote:
> From: "Steven Rostedt (Red Hat)" <rostedt@xxxxxxxxxxx>
> 
> Rewrite seq_buf_path() like it is done in seq_path() and allow
> it to accept any escape character instead of just "\n".
> 
> Making seq_buf_path() like seq_path() will help prevent problems
> when converting seq_file to use the seq_buf logic.
> 
> Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
> ---
>  include/linux/seq_buf.h  |  2 +-
>  kernel/trace/seq_buf.c   | 30 ++++++++++++++++--------------
>  kernel/trace/trace_seq.c |  2 +-
>  3 files changed, 18 insertions(+), 16 deletions(-)
> 
> diff --git a/include/linux/seq_buf.h b/include/linux/seq_buf.h
> index 97872154d51c..6d1c57d6073f 100644
> --- a/include/linux/seq_buf.h
> +++ b/include/linux/seq_buf.h
> @@ -64,7 +64,7 @@ extern int seq_buf_putc(struct seq_buf *s, unsigned char c);
>  extern int seq_buf_putmem(struct seq_buf *s, const void *mem, unsigned int len);
>  extern int seq_buf_putmem_hex(struct seq_buf *s, const void *mem,
>  			      unsigned int len);
> -extern int seq_buf_path(struct seq_buf *s, const struct path *path);
> +extern int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc);
>  
>  extern int seq_buf_bitmask(struct seq_buf *s, const unsigned long *maskp,
>  			   int nmaskbits);
> diff --git a/kernel/trace/seq_buf.c b/kernel/trace/seq_buf.c
> index 2bf582753902..243123b12d16 100644
> --- a/kernel/trace/seq_buf.c
> +++ b/kernel/trace/seq_buf.c
> @@ -272,28 +272,30 @@ int seq_buf_putmem_hex(struct seq_buf *s, const void *mem,
>   * seq_buf_path - copy a path into the sequence buffer
>   * @s: seq_buf descriptor
>   * @path: path to write into the sequence buffer.
> + * @esc: set of characters to escape in the output
>   *
>   * Write a path name into the sequence buffer.
>   *
>   * Returns zero on success, -1 on overflow

Ah, I have missed this. We should also update this comment to reflect
the change. I would also add a note that it is because of
compatibility with seq_path(). So, something like:

 * Return the number of written bytes on success, -1 on overflow
 *
 * The behavior is consistent with seq_path()

>   */
> -int seq_buf_path(struct seq_buf *s, const struct path *path)
> +int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc)
>  {
[...]
> +	if (size) {
> +		char *p = d_path(path, buf, size);
> +		if (!IS_ERR(p)) {
> +			char *end = mangle_path(buf, p, esc);
> +			if (end)
> +				res = end - buf;
>  		}
>  	}
> -	seq_buf_set_overflow(s);
> -	return -1;
> +	if (res > 0)
> +		s->len += res;
> +
> +	return res;

Best Regards,
Petr
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