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BUG/MEDIUM: thread: use pthread_self() not ha_pthread[tid] in set_affinity

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A bug was uncovered by the work on NUMA. It only triggers in the CI
with libmusl due to a race condition. What happens is that the call
to set_thread_cpu_affinity() is done very early in the polling loop,
and that it relies on ha_pthread[tid] instead of pthread_self(). The
problem is that ha_pthread[tid] is only set by the return from
pthread_create(), which might happen later depending on the number of
CPUs available to run the starting thread.

Let's just use pthread_self() here. ha_pthread[] is only used to send
signals between threads, there's no point in using it here.

This can be backported to 2.6.
This commit is contained in:
Willy Tarreau 2025-03-12 15:54:36 +01:00
parent e942305214
commit 12383fd9f5
1 changed files with 2 additions and 2 deletions
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4
src/thread.c
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@ -287,14 +287,14 @@ void set_thread_cpu_affinity()
thread_affinity_policy_data_t cpu_set = { j - 1 };
thread_port_t mthread;
mthread = pthread_mach_thread_np(ha_pthread[tid]);
mthread = pthread_mach_thread_np(pthread_self());
thread_policy_set(mthread, THREAD_AFFINITY_POLICY, (thread_policy_t)&cpu_set, 1);
set &= ~(1UL << (j - 1));
}
# else
struct hap_cpuset *set = &cpu_map[tgid - 1].thread[ti->ltid];
pthread_setaffinity_np(ha_pthread[tid], sizeof(set->cpuset), &set->cpuset);
pthread_setaffinity_np(pthread_self(), sizeof(set->cpuset), &set->cpuset);
# endif
}
#endif /* USE_CPU_AFFINITY */