Re: [PATCH 1/5] perf dso: Guard against errno==0 when dso__get_filename() returns NULL

[sashiko-bot@kernel.org]

> From: Arnaldo Carvalho de Melo <acme@redhat.com>
> 
> __open_dso() computes fd = -errno when dso__get_filename() returns NULL.
> Some failure paths in dso__get_filename() (e.g. binary type mismatch)
> return NULL without making a syscall, leaving errno at 0 from a prior
> successful call.  fd = -0 = 0, which is stdin — subsequent code treats
> it as a valid file descriptor.
> 
> Fall back to ENOENT when errno is 0, ensuring fd is always negative on
> failure.
> 
> The forced ENOENT stays in errno for the callers that check it after a
> negative fd.  It must not misdirect the try_to_open_dso() fallback
> loop, though: dso__get_filename()'s chroot fallback used to accept a
> stale ENOENT even when stat() succeeded on a non-regular file (e.g. a
> directory).  Re-stat() there and only take the chroot path when
> stat() actually failed with ENOENT [sashiko-bot review of PATCH 1/5].
> 
> Fixes: eba5102d2f0b ("perf tools: Add global list of opened dso objects")
> Reported-by: sashiko-bot <sashiko-bot@kernel.org>
> Cc: Jiri Olsa <jolsa@kernel.org>
> Reviewed-by: Ian Rogers <irogers@google.com>
> Assisted-by: Claude:claude-opus-4.6
> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20260813151148.23169-1-acme@kernel.org?part=1