Re: [PATCH core] perf data: Adding error message if perf_data__create_dir fails

["Bayduraev, Alexey V" <alexey.v.bayduraev@linux.intel.com>]

On 21.02.2022 21:24, Jiri Olsa wrote:
> On Mon, Feb 21, 2022 at 04:24:28PM +0300, Bayduraev, Alexey V wrote:
>> On 21.02.2022 1:43, Jiri Olsa wrote:
>>> On Fri, Feb 18, 2022 at 06:23:40PM +0300, Alexey Bayduraev wrote:
>>>> There is no notification about data directory creation failure. Add it.
>>>>
>>>> Signed-off-by: Alexey Bayduraev <alexey.v.bayduraev@linux.intel.com>
>>>> ---
>>>>  tools/perf/builtin-record.c | 4 +++-
>>>>  1 file changed, 3 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
>>>> index 0bc6529814b2..0306d5911de2 100644
>>>> --- a/tools/perf/builtin-record.c
>>>> +++ b/tools/perf/builtin-record.c
>>>> @@ -1186,8 +1186,10 @@ static int record__mmap_evlist(struct record *rec,
>>>>  
>>>>  	if (record__threads_enabled(rec)) {
>>>>  		ret = perf_data__create_dir(&rec->data, evlist->core.nr_mmaps);
>>>> -		if (ret)
>>>> +		if (ret) {
>>>> +			pr_err("Failed to create data directory: %s\n", strerror(errno));
>>>
>>> errno will be misleading in here, because perf_data__create_dir
>>> calls other syscalls on error path
>>
>> Mostly I want to output something like:
>>
>>   Failed to create data dir: Too many open files
>>
>> This will trigger the user to increase the open files limit.
>> Would it be better to place such message to perf_data__create_dir after 
>> open() syscall?
> 
> how about something like below (with your change)

Looks better, I will apply this to my patch.

Thanks,
Alexey

> 
> jirka
> 
> 
> ---
> diff --git a/tools/perf/util/data.c b/tools/perf/util/data.c
> index 15a4547d608e..d3382098d6f9 100644
> --- a/tools/perf/util/data.c
> +++ b/tools/perf/util/data.c
> @@ -52,8 +52,10 @@ int perf_data__create_dir(struct perf_data *data, int nr)
>  			goto out_err;
>  
>  		ret = open(file->path, O_RDWR|O_CREAT|O_TRUNC, S_IRUSR|S_IWUSR);
> -		if (ret < 0)
> +		if (ret < 0) {
> +			ret = -errno;
>  			goto out_err;
> +		}
>  
>  		file->fd = ret;
>  	}