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commit 73c7f5a87971de2797f261e1a447f68dce09284b
Author: Florian Weimer <fweimer@redhat.com>
Date: Mon Sep 20 14:56:08 2021 +0200
nptl: pthread_kill needs to return ESRCH for old programs (bug 19193)
The fix for bug 19193 breaks some old applications which appear
to use pthread_kill to probe if a thread is still running, something
that is not supported by POSIX.
(cherry picked from commit 95dba35bf05e4a5d69dfae5e9c9d4df3646a7f93)
diff --git a/nptl/pthread_kill.c b/nptl/pthread_kill.c
index fb7862eff787a94f..a44dc8f2d9baa925 100644
--- a/nptl/pthread_kill.c
+++ b/nptl/pthread_kill.c
@@ -21,8 +21,11 @@
#include <pthreadP.h>
#include <shlib-compat.h>
-int
-__pthread_kill_internal (pthread_t threadid, int signo)
+/* Sends SIGNO to THREADID. If the thread is about to exit or has
+ already exited on the kernel side, return NO_TID. Otherwise return
+ 0 or an error code. */
+static int
+__pthread_kill_implementation (pthread_t threadid, int signo, int no_tid)
{
struct pthread *pd = (struct pthread *) threadid;
if (pd == THREAD_SELF)
@@ -52,11 +55,8 @@ __pthread_kill_internal (pthread_t threadid, int signo)
signal is either not observable (the target thread has already
blocked signals at this point), or it will fail, or it might be
delivered to a new, unrelated thread that has reused the TID.
- So do not actually send the signal. Do not report an error
- because the threadid argument is still valid (the thread ID
- lifetime has not ended), and ESRCH (for example) would be
- misleading. */
- ret = 0;
+ So do not actually send the signal. */
+ ret = no_tid;
else
{
/* Using tgkill is a safety measure. pd->exit_lock ensures that
@@ -71,6 +71,15 @@ __pthread_kill_internal (pthread_t threadid, int signo)
return ret;
}
+int
+__pthread_kill_internal (pthread_t threadid, int signo)
+{
+ /* Do not report an error in the no-tid case because the threadid
+ argument is still valid (the thread ID lifetime has not ended),
+ and ESRCH (for example) would be misleading. */
+ return __pthread_kill_implementation (threadid, signo, 0);
+}
+
int
__pthread_kill (pthread_t threadid, int signo)
{
@@ -81,6 +90,7 @@ __pthread_kill (pthread_t threadid, int signo)
return __pthread_kill_internal (threadid, signo);
}
+
/* Some architectures (for instance arm) might pull raise through libgcc, so
avoid the symbol version if it ends up being used on ld.so. */
#if !IS_IN(rtld)
@@ -88,6 +98,17 @@ libc_hidden_def (__pthread_kill)
versioned_symbol (libc, __pthread_kill, pthread_kill, GLIBC_2_34);
# if OTHER_SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_34)
-compat_symbol (libc, __pthread_kill, pthread_kill, GLIBC_2_0);
+/* Variant which returns ESRCH in the no-TID case, for backwards
+ compatibility. */
+int
+attribute_compat_text_section
+__pthread_kill_esrch (pthread_t threadid, int signo)
+{
+ if (__is_internal_signal (signo))
+ return EINVAL;
+
+ return __pthread_kill_implementation (threadid, signo, ESRCH);
+}
+compat_symbol (libc, __pthread_kill_esrch, pthread_kill, GLIBC_2_0);
# endif
#endif
diff --git a/sysdeps/pthread/tst-pthread_kill-exited.c b/sysdeps/pthread/tst-pthread_kill-exited.c
index 7575fb6d58cae99c..a2fddad526666c8c 100644
--- a/sysdeps/pthread/tst-pthread_kill-exited.c
+++ b/sysdeps/pthread/tst-pthread_kill-exited.c
@@ -16,11 +16,15 @@
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
-/* This test verifies that pthread_kill returns 0 (and not ESRCH) for
- a thread that has exited on the kernel side. */
+/* This test verifies that the default pthread_kill returns 0 (and not
+ ESRCH) for a thread that has exited on the kernel side. */
+#include <errno.h>
+#include <pthread.h>
+#include <shlib-compat.h>
#include <signal.h>
#include <stddef.h>
+#include <support/check.h>
#include <support/support.h>
#include <support/xthread.h>
@@ -30,6 +34,12 @@ noop_thread (void *closure)
return NULL;
}
+#if TEST_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_34) && PTHREAD_IN_LIBC
+extern __typeof (pthread_kill) compat_pthread_kill;
+compat_symbol_reference (libpthread, compat_pthread_kill, pthread_kill,
+ GLIBC_2_0);
+#endif
+
static int
do_test (void)
{
@@ -37,7 +47,14 @@ do_test (void)
support_wait_for_thread_exit ();
+ /* NB: Always uses the default symbol due to separate compilation. */
xpthread_kill (thr, SIGUSR1);
+
+#if TEST_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_34) && PTHREAD_IN_LIBC
+ /* Old binaries need the non-conforming ESRCH error code. */
+ TEST_COMPARE (compat_pthread_kill (thr, SIGUSR1), ESRCH);
+#endif
+
xpthread_join (thr);
return 0;