Re: [PATCH v3 01/29] selftests/resctrl: Convert perror() to ksft_perror() or ksft_print_msg()

Ilpo Järvinen
2023-12-14T10:12:56Z

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On Wed, 13 Dec 2023, Reinette Chatre wrote:

> Hi Ilpo,
>
> On 12/11/2023 4:17 AM, Ilpo Järvinen wrote:
> > The resctrl selftest code contains a number of perror() calls. Some of
> > them come with hash character and some don't. The kselftest framework
> > provides ksft_perror() that is compatible with test output formatting
> > so it should be used instead of adding custom hash signs.
> >
> > Some perror() calls are too far away from anything that sets error.
> > For those call sites, ksft_print_msg() must be used instead.
> >
> > Convert perror() to ksft_perror() or ksft_print_msg().
> >
> > Other related changes:
> > - Remove hash signs
> > - Remove trailing stops & newlines from ksft_perror()
> > - Add terminating newlines for converted ksft_print_msg()
> > - Use consistent capitalization
> >
>
> Another great cleanup. Also thanks for fixing some non-sensical messages.
>
> ...
>
> > @@ -149,7 +149,7 @@ int cat_perf_miss_val(int cpu_no, int n, char *cache_type)
> > param.num_of_runs = 0;
> >
> > if (pipe(pipefd)) {
> > - perror("# Unable to create pipe");
> > + ksft_perror("Unable to create pipe");
> > return errno;
> > }
> >
> > @@ -185,7 +185,7 @@ int cat_perf_miss_val(int cpu_no, int n, char *cache_type)
> > * Just print the error message.
> > * Let while(1) run and wait for itself to be killed.
> > */
> > - perror("# failed signaling parent process");
> > + ksft_perror("Failed signaling parent process");
> >
>
> Partial writes are not actually errors and it cannot be expected that errno be set
> in these cases. In these cases I think ksft_print_msg() would be more appropriate.

I can change those to use print instead although I don't think these will
fail for other reasons than a real error as the pipe should be empty and
only single byte is written to it.

> > if (fprintf(fp, "Pid: %d \t Mem_BW_iMC: %f \t Mem_BW_resc: %lu \t Difference: %lu\n",
> > bm_pid, bw_imc, bw_resc, diff) <= 0) {
> > + ksft_perror("Could not log results");
> > fclose(fp);
> > - perror("Could not log results.");
> >
> > return errno;
>
> >From what I can tell fprintf() does not set errno on error. Perhaps this
> should rather be ksft_print_msg()?

Oh, what a stupid gotcha in libc. I just assumed it does set errno without
even checking... because why it wouldn't follow the custom. ...It seems
nothing can be relied on :-/.

--
i.