Re: Little bug in cyclictest

[Rachid Koucha <rachid.koucha@gmail.com>]

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Find attach the patch file :

$ cd rt-tests
$ patch -p1 < ../cyclictest_affinity_check.patch

On 14/08/2019 15:25, John Kacur wrote:
>
> On Wed, 14 Aug 2019, Rachid Koucha wrote:
>
>> Hi,
>>
>> First of all, many thanks for such useful tools.
>>
>> In the source code of cyclictest, I can see a mistake concerning the
>> error checking of pthread_setaffinity_np():
>>
>> Upon error, pthread functions return an error ant not -1. So, the
>> following code:
>>
>>     if (par->cpu != -1) {
>>         CPU_ZERO(&mask);
>>         CPU_SET(par->cpu, &mask);
>>         thread = pthread_self();
>>         if (pthread_setaffinity_np(thread, sizeof(mask), &mask) == -1)
>>             warn("Could not set CPU affinity to CPU #%d\n",
>>                  par->cpu);
>>     }
>>
>> should be fixed as follow:
>>
>> int status;
>>
>>     if (par->cpu != -1) {
>>         CPU_ZERO(&mask);
>>         CPU_SET(par->cpu, &mask);
>>         thread = pthread_self();
>>         if ((status = pthread_setaffinity_np(thread, sizeof(mask), &mask)) != 0)
>>             warn("Could not set CPU affinity to CPU #%d: %s (%d)\n",                  par->cpu, strerror(status), status);
>>     }
>>
>>
>> Regards,
>>
> Thanks, that looks correct. Please generate a patch and I'll apply it.
>
> John Kacur


-- 


[-- Attachment #2: cyclictest_affinity_check.patch --]
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--- old_rt-tests/src/cyclictest/cyclictest.c	2019-08-14 20:28:48.547725419 +0200
+++ new_rt-tests/src/cyclictest/cyclictest.c	2019-08-14 20:20:58.415297592 +0200
@@ -985,6 +985,7 @@
 	cpu_set_t mask;
 	pthread_t thread;
 	unsigned long smi_now, smi_old;
+        int status;
 
 	/* if we're running in numa mode, set our memory node */
 	if (par->node != -1)
@@ -994,9 +995,9 @@
 		CPU_ZERO(&mask);
 		CPU_SET(par->cpu, &mask);
 		thread = pthread_self();
-		if (pthread_setaffinity_np(thread, sizeof(mask), &mask) == -1)
-			warn("Could not set CPU affinity to CPU #%d\n",
-			     par->cpu);
+		if ((status = pthread_setaffinity_np(thread, sizeof(mask), &mask)) != 0)
+			warn("Could not set CPU affinity to CPU #%d: %s (%d)\n",
+			     par->cpu, strerror(status), status);
 	}
 
 	interval.tv_sec = par->interval / USEC_PER_SEC;