On Tue 2021-06-22 17:36:39, Andy Shevchenko wrote:

On Tue, Jun 22, 2021 at 10:06:31PM +0800, Jia He wrote:

quoted

This helper is similar to d_path() except that it doesn't take any
seqlock/spinlock. It is typical for debugging purposes. Besides,
an additional return value *prenpend_len* is used to get the full
path length of the dentry, ingoring the tail '\0'.
the full path length = end - buf - prepend_length - 1

Missed period at the end of sentence.

quoted

Previously it will skip the prepend_name() loop at once in
__prepen_path() when the buffer length is not enough or even negative.
prepend_name_with_len() will get the full length of dentry name
together with the parent recursively regardless of the buffer length.

quoted

If someone invokes snprintf() with small but positive space,
prepend_name_with_len() moves and copies the string partially.

More than that, kasprintf() will pass NULL _buf_ and _end_ as the
parameters. Hence return at the very beginning with false in this case.

These two paragraphs are talking about printf() interface, while patch has
nothing to do with it. Please, rephrase in a way that it doesn't refer to the
particular callers. Better to mention them in the corresponding printf()
patch(es).

The two paragraphs are actually repeated in the 2nd
patch. Unfortunately, they do not make sense there either because they
comment code that is modified in this patch.

We could describe it here a generic way. For example:

  prepend_name_with_len() moves and copies the path when the given
  buffer is not big enough. It cuts off the end of the path.
  It returns immediately when there is no buffer at all.


Best Regards,
Petr