[all-commits] [llvm/llvm-project] 9b237b: [ASan] Disable InstallAtForkHandler on Linux/sparc...

[Rainer Orth via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 9b237b4013e86741cf7d4fcd95a7bc70772d2286
      https://github.com/llvm/llvm-project/commit/9b237b4013e86741cf7d4fcd95a7bc70772d2286
  Author: Rainer Orth <ro at gcc.gnu.org>
  Date:   2024-09-16 (Mon, 16 Sep 2024)

  Changed paths:
    M compiler-rt/lib/asan/asan_posix.cpp

  Log Message:
  -----------
  [ASan] Disable InstallAtForkHandler on Linux/sparc64 (#108542)

When SPARC Asan testing is enabled by PR #107405, many Linux/sparc64
tests just hang like
```
#0  0xf7ae8e90 in syscall () from /usr/lib32/libc.so.6
#1  0x701065e8 in __sanitizer::FutexWait(__sanitizer::atomic_uint32_t*, unsigned int) ()
    at compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp:766
#2  0x70107c90 in Wait ()
    at compiler-rt/lib/sanitizer_common/sanitizer_mutex.cpp:35
#3  0x700f7cac in Lock ()
    at compiler-rt/lib/asan/../sanitizer_common/sanitizer_mutex.h:196
#4  Lock ()
    at compiler-rt/lib/asan/../sanitizer_common/sanitizer_thread_registry.h:98
#5  LockThreads ()
    at compiler-rt/lib/asan/asan_thread.cpp:489
#6  0x700e9c8c in __asan::BeforeFork() ()
    at compiler-rt/lib/asan/asan_posix.cpp:157
#7  0xf7ac83f4 in ?? () from /usr/lib32/libc.so.6
Backtrace stopped: previous frame identical to this frame (corrupt stack?)
```
It turns out that this happens in tests using `internal_fork` (e.g.
invoking `llvm-symbolizer`): unlike most other Linux targets, which use
`clone`, Linux/sparc64 has to use `__fork` instead. While `clone`
doesn't trigger `pthread_atfork` handlers, `__fork` obviously does,
causing the hang.

To avoid this, this patch disables `InstallAtForkHandler` and lets the
ASan tests run to completion.

Tested on `sparc64-unknown-linux-gnu`.



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