[compiler-rt] r192448 - tsan: fix epoll_ctl interceptor

[Dmitry Vyukov]

Author: dvyukov
Date: Fri Oct 11 08:33:22 2013
New Revision: 192448

URL: http://llvm.org/viewvc/llvm-project?rev=192448&view=rev
Log:
tsan: fix epoll_ctl interceptor

Currently data-race-test unittests fail with the following false positive:


WARNING: ThreadSanitizer: data race (pid=20365)
  Write of size 8 at 0x7da000008050 by thread T54:
    #0 close tsan_interceptors.cc:1483 (racecheck_unittest-linux-amd64-O0+0x0000000eb34a)
    #1 NegativeTests_epoll::Worker2() unittest/posix_tests.cc:1148 (racecheck_unittest-linux-amd64-O0+0x0000000cc6b1)
    #2 MyThread::ThreadBody(MyThread*) unittest/./thread_wrappers_pthread.h:367 (racecheck_unittest-linux-amd64-O0+0x000000097500)

  Previous read of size 8 at 0x7da000008050 by thread T49:
    #0 epoll_ctl tsan_interceptors.cc:1646 (racecheck_unittest-linux-amd64-O0+0x0000000e9fee)
    #1 NegativeTests_epoll::Worker1() unittest/posix_tests.cc:1140 (racecheck_unittest-linux-amd64-O0+0x0000000cc5b5)
    #2 MyThread::ThreadBody(MyThread*) unittest/./thread_wrappers_pthread.h:367 (racecheck_unittest-linux-amd64-O0+0x000000097500)



Modified:
    compiler-rt/trunk/lib/tsan/rtl/tsan_interceptors.cc

Modified: compiler-rt/trunk/lib/tsan/rtl/tsan_interceptors.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/tsan/rtl/tsan_interceptors.cc?rev=192448&r1=192447&r2=192448&view=diff
==============================================================================
--- compiler-rt/trunk/lib/tsan/rtl/tsan_interceptors.cc (original)
+++ compiler-rt/trunk/lib/tsan/rtl/tsan_interceptors.cc Fri Oct 11 08:33:22 2013
@@ -1645,21 +1645,23 @@ TSAN_INTERCEPTOR(void*, opendir, char *p
 
 TSAN_INTERCEPTOR(int, epoll_ctl, int epfd, int op, int fd, void *ev) {
   SCOPED_TSAN_INTERCEPTOR(epoll_ctl, epfd, op, fd, ev);
-  if (op == EPOLL_CTL_ADD && epfd >= 0) {
+  if (epfd >= 0)
+    FdAccess(thr, pc, epfd);
+  if (epfd >= 0 && fd >= 0)
+    FdAccess(thr, pc, fd);
+  if (op == EPOLL_CTL_ADD && epfd >= 0)
     FdRelease(thr, pc, epfd);
-  }
   int res = REAL(epoll_ctl)(epfd, op, fd, ev);
-  if (fd >= 0)
-    FdAccess(thr, pc, fd);
   return res;
 }
 
 TSAN_INTERCEPTOR(int, epoll_wait, int epfd, void *ev, int cnt, int timeout) {
   SCOPED_TSAN_INTERCEPTOR(epoll_wait, epfd, ev, cnt, timeout);
+  if (epfd >= 0)
+    FdAccess(thr, pc, epfd);
   int res = BLOCK_REAL(epoll_wait)(epfd, ev, cnt, timeout);
-  if (res > 0 && epfd >= 0) {
+  if (res > 0 && epfd >= 0)
     FdAcquire(thr, pc, epfd);
-  }
   return res;
 }