linux-kernel - Re: [PATCH] selftests/bpf: Make bpf_util work on uniprocessor systems

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Date:   Sat, 09 Sep 2017 01:05:21 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Thomas Meyer <thomas@...3r.de>
CC:     linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
        shuah@...nel.org
Subject: Re: [PATCH] selftests/bpf: Make bpf_util work on uniprocessor systems

On 09/09/2017 01:01 AM, Alexei Starovoitov wrote:
> On Fri, Sep 08, 2017 at 01:19:23PM +0200, Thomas Meyer wrote:
>> The current implementation fails to work on uniprocessor systems.
>> Fix the parser to also handle the uniprocessor case.
>>
>> Signed-off-by: Thomas Meyer <thomas@...3r.de>
>
> Thanks for the fix. lgtm
> Acked-by: Alexei Starovoitov <ast@...nel.org>

Looks good from here as well:

Acked-by: Daniel Borkmann <daniel@...earbox.net>

> This time it's ok to go via selftest tree, but next time please use net-next/net
> to avoid conflicts.

+1

> Thanks
>
>> ---
>>   tools/testing/selftests/bpf/bpf_util.h | 17 +++++++++--------
>>   1 file changed, 9 insertions(+), 8 deletions(-)
>>
>> diff --git a/tools/testing/selftests/bpf/bpf_util.h b/tools/testing/selftests/bpf/bpf_util.h
>> index 20ecbaa0d85d..6c53a8906eff 100644
>> --- a/tools/testing/selftests/bpf/bpf_util.h
>> +++ b/tools/testing/selftests/bpf/bpf_util.h
>> @@ -12,6 +12,7 @@ static inline unsigned int bpf_num_possible_cpus(void)
>>   	unsigned int start, end, possible_cpus = 0;
>>   	char buff[128];
>>   	FILE *fp;
>> +	int n;
>>
>>   	fp = fopen(fcpu, "r");
>>   	if (!fp) {
>> @@ -20,17 +21,17 @@ static inline unsigned int bpf_num_possible_cpus(void)
>>   	}
>>
>>   	while (fgets(buff, sizeof(buff), fp)) {
>> -		if (sscanf(buff, "%u-%u", &start, &end) == 2) {
>> -			possible_cpus = start == 0 ? end + 1 : 0;
>> -			break;
>> +		n = sscanf(buff, "%u-%u", &start, &end);
>> +		if (n == 0) {
>> +			printf("Failed to retrieve # possible CPUs!\n");
>> +			exit(1);
>> +		} else if (n == 1) {
>> +			end = start;
>>   		}
>> +		possible_cpus = start == 0 ? end + 1 : 0;
>> +		break;
>>   	}
>> -
>>   	fclose(fp);
>> -	if (!possible_cpus) {
>> -		printf("Failed to retrieve # possible CPUs!\n");
>> -		exit(1);
>> -	}
>>
>>   	return possible_cpus;
>>   }
>> --
>> 2.11.0
>>