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| author | Florian Weimer <fweimer@redhat.com> | 2019-02-08 12:55:21 +0100 |
|---|---|---|
| committer | Florian Weimer <fweimer@redhat.com> | 2019-02-08 12:55:21 +0100 |
| commit | 60f80624257ef84eacfd9b400bda1b5a5e8e7816 (patch) | |
| tree | 35b8283c274af5b4b3c3b15e7939dd05edc4df23 /ChangeLog | |
| parent | a9f60b1571cc7821cd6bc4dbeba12194d484e7f5 (diff) | |
| download | glibc-60f80624257ef84eacfd9b400bda1b5a5e8e7816.tar.gz glibc-60f80624257ef84eacfd9b400bda1b5a5e8e7816.tar.xz glibc-60f80624257ef84eacfd9b400bda1b5a5e8e7816.zip | |
nptl: Avoid fork handler lock for async-signal-safe fork [BZ #24161]
Commit 27761a1042daf01987e7d79636d0c41511c6df3c ("Refactor atfork
handlers") introduced a lock, atfork_lock, around fork handler list
accesses. It turns out that this lock occasionally results in
self-deadlocks in malloc/tst-mallocfork2:
(gdb) bt
#0 __lll_lock_wait_private ()
at ../sysdeps/unix/sysv/linux/x86_64/lowlevellock.S:63
#1 0x00007f160c6f927a in __run_fork_handlers (who=(unknown: 209394016),
who@entry=atfork_run_prepare) at register-atfork.c:116
#2 0x00007f160c6b7897 in __libc_fork () at ../sysdeps/nptl/fork.c:58
#3 0x00000000004027d6 in sigusr1_handler (signo=<optimized out>)
at tst-mallocfork2.c:80
#4 sigusr1_handler (signo=<optimized out>) at tst-mallocfork2.c:64
#5 <signal handler called>
#6 0x00007f160c6f92e4 in __run_fork_handlers (who=who@entry=atfork_run_parent)
at register-atfork.c:136
#7 0x00007f160c6b79a2 in __libc_fork () at ../sysdeps/nptl/fork.c:152
#8 0x0000000000402567 in do_test () at tst-mallocfork2.c:156
#9 0x0000000000402dd2 in support_test_main (argc=1, argv=0x7ffc81ef1ab0,
config=config@entry=0x7ffc81ef1970) at support_test_main.c:350
#10 0x0000000000402362 in main (argc=<optimized out>, argv=<optimized out>)
at ../support/test-driver.c:168
If no locking happens in the single-threaded case (where fork is
expected to be async-signal-safe), this deadlock is avoided.
(pthread_atfork is not required to be async-signal-safe, so a fork
call from a signal handler interrupting pthread_atfork is not
a problem.)
(cherry picked from commit 669ff911e2571f74a2668493e326ac9a505776bd)
Diffstat (limited to 'ChangeLog')
| -rw-r--r-- | ChangeLog | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/ChangeLog b/ChangeLog index 82802f3367..f3477bbff9 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,13 @@ +2019-02-08 Florian Weimer <fweimer@redhat.com> + + [BZ #24161] + * sysdeps/nptl/fork.h (__run_fork_handlers): Add multiple_threads + argument. + * nptl/register-atfork.c (__run_fork_handlers): Only perform + locking if the new do_locking argument is true. + * sysdeps/nptl/fork.c (__libc_fork): Pass multiple_threads to + __run_fork_handlers. + 2019-02-07 Stefan Liebler <stli@linux.ibm.com> [BZ #24180] |