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

Petr Mladek
2014-11-06T15:01:51Z

On Tue 2014-11-04 10:52:41, Steven Rostedt wrote:
> From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
>
> 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@goodmis.org>
> ---
> 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