commit 73c7f5a87971de2797f261e1a447f68dce09284b Author: Florian Weimer 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 #include -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 . */ -/* 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 +#include +#include #include #include +#include #include #include @@ -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;