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tsan: fix deadlock with pthread_atfork callbacks
This fixes the bug reported at: https://groups.google.com/forum/#!topic/thread-sanitizer/e_zB9gYqFHM A pthread_atfork callback triggers a data race and we deadlock on the report_mtx. Ignore memory access in the pthread_atfork callbacks to prevent the deadlock.
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// RUN: %clang_tsan -O1 %s -o %t && %run %t 2>&1 | FileCheck %s | ||
// Regression test for | ||
// https://groups.google.com/d/msg/thread-sanitizer/e_zB9gYqFHM/DmAiTsrLAwAJ | ||
// pthread_atfork() callback triggers a data race and we deadlocked | ||
// on the report_mtx as we lock it around fork. | ||
#include "test.h" | ||
#include <sys/types.h> | ||
#include <sys/wait.h> | ||
#include <errno.h> | ||
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int glob = 0; | ||
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void *worker(void *unused) { | ||
glob++; | ||
barrier_wait(&barrier); | ||
return NULL; | ||
} | ||
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void atfork() { | ||
glob++; | ||
} | ||
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int main() { | ||
barrier_init(&barrier, 2); | ||
pthread_atfork(atfork, NULL, NULL); | ||
pthread_t t; | ||
pthread_create(&t, NULL, worker, NULL); | ||
barrier_wait(&barrier); | ||
pid_t pid = fork(); | ||
if (pid < 0) { | ||
fprintf(stderr, "fork failed: %d\n", errno); | ||
return 1; | ||
} | ||
if (pid == 0) { | ||
fprintf(stderr, "CHILD\n"); | ||
return 0; | ||
} | ||
if (pid != waitpid(pid, NULL, 0)) { | ||
fprintf(stderr, "waitpid failed: %d\n", errno); | ||
return 1; | ||
} | ||
pthread_join(t, NULL); | ||
fprintf(stderr, "PARENT\n"); | ||
return 0; | ||
} | ||
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// CHECK-NOT: ThreadSanitizer: data race | ||
// CHECK: CHILD | ||
// CHECK: PARENT |