compiler-rt/test/tsan/signal_thread_sigctx_race.cpp

   1 // RUN: %clangxx_tsan %s -o %t && %run %t 2>&1 | FileCheck %s
   2 // UNSUPPORTED: darwin
   3
   4 #include <errno.h>
   5 #include <limits.h>
   6 #include <pthread.h>
   7 #include <signal.h>
   8 #include <stdio.h>
   9 #include <stdlib.h>
  10 #include <sys/select.h>
  11 #include <sys/time.h>
  12 #include <sys/types.h>
  13 #include <unistd.h>
  14
  15 // This attempts to exercise a race condition where both a thread and its signal
  16 // handler allocate the SigCtx. If the race is allowed, it leads to a leak and
  17 // the first signal being dropped.
  18 // Spawn threads in a loop and send it SIGUSR1 concurrently with the thread
  19 // doing a bogus kill() call. The signal handler writes to a self-pipe which the
  20 // thread detects and then exits. A dropped signal results in a timeout.
  21 int pipes[2];
  22 static void handler(int sig) { write(pipes[1], "x", 1); }
  23
  24 static int do_select() {
  25   struct timeval tvs {
  26     0, 1000
  27   };
  28   fd_set fds;
  29   FD_ZERO(&fds);
  30   FD_SET(pipes[0], &fds);
  31   return select(pipes[0] + 1, &fds, 0, 0, &tvs);
  32 }
  33
  34 static void *thr(void *p) {
  35   // This kill() is expected to fail; it exists only to trigger a call to SigCtx
  36   // outside of the signal handler.
  37   kill(INT_MIN, 0);
  38   int success = 0;
  39   for (int i = 0; i < 1024; i++) {
  40     if (do_select() > 0) {
  41       success = 1;
  42       break;
  43     }
  44   }
  45   if (success) {
  46     char c;
  47     read(pipes[0], &c, 1);
  48   } else {
  49     fprintf(stderr, "Failed to receive signal\n");
  50     exit(1);
  51   }
  52   return p;
  53 }
  54
  55 int main() {
  56   if (pipe(pipes)) {
  57     perror("pipe");
  58     exit(1);
  59   }
  60
  61   struct sigaction act = {};
  62   act.sa_handler = &handler;
  63   if (sigaction(SIGUSR1, &act, 0)) {
  64     perror("sigaction");
  65     exit(1);
  66   }
  67
  68   for (int i = 0; i < (1 << 10); i++) {
  69     pthread_t th{};
  70     if (pthread_create(&th, 0, thr, 0)) {
  71       perror("pthread_create");
  72       exit(1);
  73     }
  74     pthread_kill(th, SIGUSR1);
  75     pthread_join(th, 0);
  76   }
  77
  78   fprintf(stderr, "DONE\n");
  79   return 0;
  80 }
  81
  82 // CHECK-NOT: WARNING: ThreadSanitizer:
  83 // CHECK: DONE
  84 // CHECK-NOT: WARNING: ThreadSanitizer: