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7779dbd266
if thread id was reused by the kernel between the time pthread_kill read it from the userspace pthread_t object and the time of the tgkill syscall, a signal could be sent to the wrong thread. the tgkill syscall was supposed to prevent this race (versus the old tkill syscall) but it can't; it can only help in the case where the tid is reused in a different process, but not when the tid is reused in the same process. the only solution i can see is an extra lock to prevent threads from exiting while another thread is trying to pthread_kill them. it should be very very cheap in the non-contended case.
11 lines
207 B
C
11 lines
207 B
C
#include "pthread_impl.h"
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int pthread_kill(pthread_t t, int sig)
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{
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int r;
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__lock(&t->killlock);
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r = t->dead ? ESRCH : -__syscall(SYS_tgkill, t->pid, t->tid, sig);
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a_store(&t->killlock, 0);
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return r;
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}
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