Re: [PATCH v1 1/5] perf trace-event: Report tracepoint format errors with NULL and errno

[sashiko-bot@kernel.org]

> trace_event__tp_format() encoded failure with ERR_PTR() while
> trace_event__tp_format_id() returned a plain NULL when tep_find_event()
> found nothing, and tp_format() itself returned NULL when
> tep_parse_format() failed, as its return value was discarded. Callers
> test with IS_ERR(), which NULL does not satisfy, so those two failures
> were taken for success. In syscall__read_info() that leads straight to:
> 
> 	if (IS_ERR(sc->tp_format)) {
> 		...
> 		return err;
> 	}
> 	if (syscall__alloc_arg_fmts(sc, sc->tp_format->format.nr_fields - 1))
> 
> which dereferences NULL when a format file fails to parse.
> 
> Mixing encoded error pointers with pointers that are compared against
> NULL is what allows that to happen, so drop ERR_PTR() here and report
> failures the way the rest of these paths already expect, by returning
> NULL with errno set. evsel__tp_format() no longer has to translate the
> error back into errno before printing it with %m, and the remaining
> callers become NULL tests.
> 
> syscall__scnprintf_args() gains back its fallback of printing raw
> arguments: it asked for IS_ERR(sc->tp_format), but syscall__read_info()
> had already replaced the error pointer with NULL, so the branch could
> never be taken.
> 
> Assisted-by: Antigravity:gemini-3.1-pro
> Signed-off-by: Ian Rogers <irogers@google.com>

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

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Sashiko AI review · https://sashiko.dev/#/patchset/20260918063249.2172589-1-irogers@google.com?part=1