diff mbox series

[v2,5/8] nptl: Implement raise in terms of pthread_kill

Message ID 20201207212757.3948164-5-adhemerval.zanella@linaro.org
State New
Headers show
Series [v2,1/8] nptl: Move Linux pthread_kill to nptl | expand

Commit Message

Adhemerval Zanella Dec. 7, 2020, 9:27 p.m. UTC
Changes from previous version:

  * Handle vfork usage for raise and obtain the TID using a syscall
    instead of reading from TCB.

--

Now that pthread_kill is provided by libc.so and async-signal-safe,
it is possible to implement the generic POSIX implementation as
pthread_kill(pthread_self(), sig).

For Linux implementation, pthread_kill read the targetting TID from
the TCB.  For raise, this it not possible because it would make raise
fail when issue after vfork (where creates the resulting process
has a different TID from the parent, but its TCB is not updated as
for pthread_create).  For this case, gettid is called directly.

Checked on x86_64-linux-gnu.
---
 include/pthread.h               |  5 ++++
 nptl/pthreadP.h                 |  4 +--
 nptl/pthread_kill.c             | 40 +++++++++++++------------
 nptl/pthread_self.c             |  4 ++-
 sysdeps/htl/pthreadP.h          |  2 --
 sysdeps/posix/raise.c           | 11 +++++--
 sysdeps/unix/sysv/linux/raise.c | 52 ---------------------------------
 7 files changed, 41 insertions(+), 77 deletions(-)
 delete mode 100644 sysdeps/unix/sysv/linux/raise.c
diff mbox series

Patch

diff --git a/include/pthread.h b/include/pthread.h
index 858c869a16..2623fb5e95 100644
--- a/include/pthread.h
+++ b/include/pthread.h
@@ -13,4 +13,9 @@  extern int __pthread_barrier_wait (pthread_barrier_t *__barrier)
 
 /* This function is called to initialize the pthread library.  */
 extern void __pthread_initialize (void) __attribute__ ((weak));
+
+extern int __pthread_kill (pthread_t threadid, int signo);
+
+extern pthread_t __pthread_self (void);
+
 #endif
diff --git a/nptl/pthreadP.h b/nptl/pthreadP.h
index a7510f9f63..968adcdb6a 100644
--- a/nptl/pthreadP.h
+++ b/nptl/pthreadP.h
@@ -521,11 +521,11 @@  extern int __pthread_once (pthread_once_t *once_control,
 			   void (*init_routine) (void));
 extern int __pthread_atfork (void (*prepare) (void), void (*parent) (void),
 			     void (*child) (void));
-extern pthread_t __pthread_self (void);
+libc_hidden_proto (__pthread_self)
 extern int __pthread_equal (pthread_t thread1, pthread_t thread2);
 extern int __pthread_detach (pthread_t th);
 extern int __pthread_cancel (pthread_t th);
-extern int __pthread_kill (pthread_t threadid, int signo);
+libc_hidden_proto (__pthread_kill)
 extern void __pthread_exit (void *value) __attribute__ ((__noreturn__));
 extern int __pthread_join (pthread_t threadid, void **thread_return);
 extern int __pthread_setcanceltype (int type, int *oldtype);
diff --git a/nptl/pthread_kill.c b/nptl/pthread_kill.c
index 006322ea9f..cf12fa743f 100644
--- a/nptl/pthread_kill.c
+++ b/nptl/pthread_kill.c
@@ -30,28 +30,32 @@  __pthread_kill (pthread_t threadid, int signo)
   sigset_t set;
   __libc_signal_block_all (&set);
 
-  int val;
-
-  /* Force load of pd->tid into local variable or register.  Otherwise
-     if a thread exits between ESRCH test and tgkill, we might return
-     EINVAL, because pd->tid would be cleared by the kernel.  */
+  pid_t tid;
   struct pthread *pd = (struct pthread *) threadid;
-  pid_t tid = atomic_forced_read (pd->tid);
-  if (__glibc_unlikely (tid <= 0))
-    /* Not a valid thread handle.  */
-    val = ESRCH;
-  else
-    {
-      /* We have a special syscall to do the work.  */
-      pid_t pid = __getpid ();
 
-      val = INTERNAL_SYSCALL_CALL (tgkill, pid, tid, signo);
-      val = (INTERNAL_SYSCALL_ERROR_P (val)
-	    ? INTERNAL_SYSCALL_ERRNO (val) : 0);
-    }
+  if (pd == THREAD_SELF)
+    tid = INLINE_SYSCALL_CALL (gettid);
+  else
+    /* Force load of pd->tid into local variable or register.  Otherwise
+       if a thread exits between ESRCH test and tgkill, we might return
+       EINVAL, because pd->tid would be cleared by the kernel.  */
+    tid = atomic_forced_read (pd->tid);
+
+   int val;
+   if (__glibc_likely (tid > 0))
+     {
+       pid_t pid = __getpid ();
+
+       val = INTERNAL_SYSCALL_CALL (tgkill, pid, tid, signo);
+       val = (INTERNAL_SYSCALL_ERROR_P (val)
+	     ? INTERNAL_SYSCALL_ERRNO (val) : 0);
+     }
+   else
+     val = ESRCH;
 
   __libc_signal_restore_set (&set);
 
   return val;
 }
-strong_alias (__pthread_kill, pthread_kill)
+libc_hidden_def (__pthread_kill)
+weak_alias (__pthread_kill, pthread_kill)
diff --git a/nptl/pthread_self.c b/nptl/pthread_self.c
index 00a8474909..4fab462bbf 100644
--- a/nptl/pthread_self.c
+++ b/nptl/pthread_self.c
@@ -20,7 +20,9 @@ 
 #include <tls.h>
 
 pthread_t
-pthread_self (void)
+__pthread_self (void)
 {
   return (pthread_t) THREAD_SELF;
 }
+libc_hidden_def (__pthread_self)
+weak_alias (__pthread_self, pthread_self)
diff --git a/sysdeps/htl/pthreadP.h b/sysdeps/htl/pthreadP.h
index bf00f7d2f0..befe18b421 100644
--- a/sysdeps/htl/pthreadP.h
+++ b/sysdeps/htl/pthreadP.h
@@ -31,8 +31,6 @@  extern void __pthread_init_static_tls (struct link_map *) attribute_hidden;
 
 /* These represent the interface used by glibc itself.  */
 
-extern pthread_t __pthread_self (void);
-extern int __pthread_kill (pthread_t threadid, int signo);
 extern struct __pthread **__pthread_threads;
 
 extern int __pthread_mutex_init (pthread_mutex_t *__mutex, const pthread_mutexattr_t *__attr);
diff --git a/sysdeps/posix/raise.c b/sysdeps/posix/raise.c
index 32cb108f0b..586116fc1c 100644
--- a/sysdeps/posix/raise.c
+++ b/sysdeps/posix/raise.c
@@ -16,13 +16,20 @@ 
    <https://www.gnu.org/licenses/>.  */
 
 #include <signal.h>
-#include <unistd.h>
+#include <errno.h>
+#include <pthread.h>
 
 /* Raise the signal SIG.  */
 int
 raise (int sig)
 {
-  return __kill (__getpid (), sig);
+  int ret = __pthread_kill (__pthread_self (), sig);
+  if (ret != 0)
+    {
+      __set_errno (ret);
+      ret = -1;
+    }
+  return ret;
 }
 libc_hidden_def (raise)
 weak_alias (raise, gsignal)
diff --git a/sysdeps/unix/sysv/linux/raise.c b/sysdeps/unix/sysv/linux/raise.c
deleted file mode 100644
index 3b90ae1d55..0000000000
--- a/sysdeps/unix/sysv/linux/raise.c
+++ /dev/null
@@ -1,52 +0,0 @@ 
-/* Copyright (C) 2002-2020 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-   Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, see
-   <https://www.gnu.org/licenses/>.  */
-
-#include <signal.h>
-#include <sysdep.h>
-#include <errno.h>
-#include <sys/types.h>
-#include <unistd.h>
-#include <internal-signals.h>
-
-int
-raise (int sig)
-{
-  /* rt_sigprocmask may fail if:
-
-     1. sigsetsize != sizeof (sigset_t) (EINVAL)
-     2. a failure in copy from/to user space (EFAULT)
-     3. an invalid 'how' operation (EINVAL)
-
-     The first case is already handle in glibc syscall call by using the arch
-     defined _NSIG.  Second case is handled by using a stack allocated mask.
-     The last one should be handled by the block/unblock functions.  */
-
-  sigset_t set;
-  __libc_signal_block_app (&set);
-
-  pid_t pid = INTERNAL_SYSCALL_CALL (getpid);
-  pid_t tid = INTERNAL_SYSCALL_CALL (gettid);
-
-  int ret = INLINE_SYSCALL_CALL (tgkill, pid, tid, sig);
-
-  __libc_signal_restore_set (&set);
-
-  return ret;
-}
-libc_hidden_def (raise)
-weak_alias (raise, gsignal)