Update.

2003-12-20  Ulrich Drepper  <drepper@redhat.com>

	* elf/rtld.c (dl_main): Optimize order or subexpressions in if().

8 files changed, 78 insertions, 18 deletions

diff --git a/nptl/ChangeLog b/nptl/ChangeLog
index 5e81694058..69fb0ec703 100644
--- a/nptl/ChangeLog
+++ b/nptl/ChangeLog
@@ -2,6 +2,15 @@
 
 	* sysdeps/unix/sysv/linux/Makefile (CFLAGS-getpid.c): Define.
 	* sysdeps/unix/sysv/linux/getpid.c: New file.
+	* pthread_cancel.c: Add comment explaining use of PID field.
+	* sysdeps/unix/sysv/linux/pthread_kill.c: Likewise.
+	* pthread_getattr_np.c: Use abs() when comparing PID and TID fields.
+	* sysdeps/unix/sysv/linux/fork.c: Negate PID field of parent
+	temporarily to signal the field must not be relied on and updated
+	by getpid().
+	* sysdeps/unix/sysv/linux/pt-raise.c: Handle case where PID is
+	temporarily negative.
+	* sysdeps/unix/sysv/linux/raise.c: Likewise.
 
 2003-12-19  Ulrich Drepper  <drepper@redhat.com>
 
diff --git a/nptl/pthread_cancel.c b/nptl/pthread_cancel.c
index 1523da82aa..8d1b8640f8 100644
--- a/nptl/pthread_cancel.c
+++ b/nptl/pthread_cancel.c
@@ -65,6 +65,12 @@ pthread_cancel (th)
 	     thread as canceled.  */
 	  INTERNAL_SYSCALL_DECL (err);
 
+	  /* One comment: The PID field in the TCB can temporarily be
+	     changed (in fork).  But this must not affect this code
+	     here.  Since this function would have to be called while
+	     the thread is executing fork, it would have to happen in
+	     a signal handler.  But this is no allowed, pthread_cancel
+	     is not guaranteed to be async-safe.  */
 	  int val;
 #if __ASSUME_TGKILL
 	  val = INTERNAL_SYSCALL (tgkill, err, 3,
diff --git a/nptl/pthread_getattr_np.c b/nptl/pthread_getattr_np.c
index 9cc948f4c6..f66e97fa68 100644
--- a/nptl/pthread_getattr_np.c
+++ b/nptl/pthread_getattr_np.c
@@ -70,7 +70,7 @@ pthread_getattr_np (thread_id, attr)
     {
       /* No stack information available.  This must be for the initial
 	 thread.  Get the info in some magical way.  */
-      assert (thread->pid == thread->tid);
+      assert (abs (thread->pid) == thread->tid);
 
       /* Defined in ld.so.  */
       extern void *__libc_stack_end;
diff --git a/nptl/sysdeps/unix/sysv/linux/fork.c b/nptl/sysdeps/unix/sysv/linux/fork.c
index 84bf3793b6..840974401b 100644
--- a/nptl/sysdeps/unix/sysv/linux/fork.c
+++ b/nptl/sysdeps/unix/sysv/linux/fork.c
@@ -117,6 +117,12 @@ __libc_fork (void)
   pid_t ppid = THREAD_GETMEM (THREAD_SELF, tid);
 #endif
 
+  /* We need to prevent the getpid() code to update the PID field so
+     that, if a signal arrives in the child very early and the signal
+     handler uses getpid(), the value returned is correct.  */
+  pid_t parentpid = THREAD_GETMEM (THREAD_SELF, pid);
+  THREAD_SETMEM (THREAD_SELF, pid, -parentpid);
+
 #ifdef ARCH_FORK
   pid = ARCH_FORK ();
 #else
@@ -135,7 +141,7 @@ __libc_fork (void)
 	*__fork_generation_pointer += 4;
 
       /* Adjust the PID field for the new process.  */
-      self->pid = self->tid;
+      THREAD_SETMEM (self, pid, THREAD_GETMEM (self, tid));
 
 #if HP_TIMING_AVAIL
       /* The CPU clock of the thread and process have to be set to zero.  */
@@ -180,6 +186,9 @@ __libc_fork (void)
     {
       assert (THREAD_GETMEM (THREAD_SELF, tid) == ppid);
 
+      /* Restore the PID value.  */
+      THREAD_SETMEM (THREAD_SELF, pid, parentpid);
+
       /* We execute this even if the 'fork' call failed.  */
       _IO_list_unlock ();
 
diff --git a/nptl/sysdeps/unix/sysv/linux/getpid.c b/nptl/sysdeps/unix/sysv/linux/getpid.c
index 75decc1385..7efe3f2768 100644
--- a/nptl/sysdeps/unix/sysv/linux/getpid.c
+++ b/nptl/sysdeps/unix/sysv/linux/getpid.c
@@ -22,21 +22,31 @@
 #include <sysdep.h>
 
 
+#ifndef NOT_IN_libc
+static pid_t really_getpid (pid_t oldval);
+#endif
+
+
 pid_t
 __getpid (void)
 {
-  pid_t result;
 #ifndef NOT_IN_libc
-  result = THREAD_GETMEM (THREAD_SELF, pid);
-  if (__builtin_expect (result == 0, 0))
+  pid_t result = THREAD_GETMEM (THREAD_SELF, pid);
+  if (__builtin_expect (result <= 0, 0))
+    result = really_getpid (result);
+  return result;
+}
+
+static pid_t
+really_getpid (pid_t oldval)
+{
 #endif
-    {
-      INTERNAL_SYSCALL_DECL (err);
-      result = INTERNAL_SYSCALL (getpid, err, 0);
+  INTERNAL_SYSCALL_DECL (err);
+  pid_t result = INTERNAL_SYSCALL (getpid, err, 0);
 #ifndef NOT_IN_libc
-      THREAD_SETMEM (THREAD_SELF, pid, result);
+  if (oldval == 0)
+    THREAD_SETMEM (THREAD_SELF, pid, result);
 #endif
-    }
   return result;
 }
 libc_hidden_def (__getpid)
diff --git a/nptl/sysdeps/unix/sysv/linux/pt-raise.c b/nptl/sysdeps/unix/sysv/linux/pt-raise.c
index 2efd7616bf..9161e29e28 100644
--- a/nptl/sysdeps/unix/sysv/linux/pt-raise.c
+++ b/nptl/sysdeps/unix/sysv/linux/pt-raise.c
@@ -28,13 +28,22 @@ int
 raise (sig)
      int sig;
 {
+#if __ASSUME_TGKILL || defined __NR_tgkill
+  /* raise is an async-safe function.  It could be called while the
+     fork function temporarily invalidated the PID field.  Adjust for
+     that.  */
+  pid_t pid = THREAD_GETMEM (THREAD_SELF, pid);
+  if (__builtin_expect (pid < 0, 0))
+    pid = -pid;
+#endif
+
 #if __ASSUME_TGKILL
-  return INLINE_SYSCALL (tgkill, 3, THREAD_GETMEM (THREAD_SELF, pid),
-			 THREAD_GETMEM (THREAD_SELF, tid), sig);
+  return INLINE_SYSCALL (tgkill, 3, pid, THREAD_GETMEM (THREAD_SELF, tid),
+			 sig);
 #else
 # ifdef __NR_tgkill
-  int res = INLINE_SYSCALL (tgkill, 3, THREAD_GETMEM (THREAD_SELF, pid),
-			    THREAD_GETMEM (THREAD_SELF, tid), sig);
+  int res = INLINE_SYSCALL (tgkill, 3, pid, THREAD_GETMEM (THREAD_SELF, tid),
+			    sig);
   if (res != -1 || errno != ENOSYS)
     return res;
 # endif
diff --git a/nptl/sysdeps/unix/sysv/linux/pthread_kill.c b/nptl/sysdeps/unix/sysv/linux/pthread_kill.c
index 6967acd92b..87577be4dc 100644
--- a/nptl/sysdeps/unix/sysv/linux/pthread_kill.c
+++ b/nptl/sysdeps/unix/sysv/linux/pthread_kill.c
@@ -44,6 +44,11 @@ __pthread_kill (threadid, signo)
   /* We have a special syscall to do the work.  */
   INTERNAL_SYSCALL_DECL (err);
 
+  /* One comment: The PID field in the TCB can temporarily be changed
+     (in fork).  But this must not affect this code here.  Since this
+     function would have to be called while the thread is executing
+     fork, it would have to happen in a signal handler.  But this is
+     no allowed, pthread_kill is not guaranteed to be async-safe.  */
   int val;
 #if __ASSUME_TGKILL
   val = INTERNAL_SYSCALL (tgkill, err, 3, THREAD_GETMEM (THREAD_SELF, pid),
diff --git a/nptl/sysdeps/unix/sysv/linux/raise.c b/nptl/sysdeps/unix/sysv/linux/raise.c
index 25d3ed8afd..268ba87b29 100644
--- a/nptl/sysdeps/unix/sysv/linux/raise.c
+++ b/nptl/sysdeps/unix/sysv/linux/raise.c
@@ -29,6 +29,9 @@ raise (sig)
      int sig;
 {
   struct pthread *pd = THREAD_SELF;
+#if __ASSUME_TGKILL || defined __NR_tgkill
+  pid_t pid = THREAD_GETMEM (pd, pid);
+#endif
   pid_t selftid = THREAD_GETMEM (pd, tid);
   if (selftid == 0)
     {
@@ -41,15 +44,24 @@ raise (sig)
 #endif
       THREAD_SETMEM (pd, tid, selftid);
 
-      /* In this case the TID and PID are the same.  */
-      THREAD_SETMEM (pd, pid, selftid);
+      /* We do not set the PID field in the TID here since we might be
+	 called from a signal handler while the thread executes fork.  */
+      pid = selftid;
     }
+#if __ASSUME_TGKILL || defined __NR_tgkill
+  else
+    /* raise is an async-safe function.  It could be called while the
+       fork function temporarily invalidated the PID field.  Adjust for
+       that.  */
+    if (__builtin_expect (pid < 0, 0))
+      pid = -pid;
+#endif
 
 #if __ASSUME_TGKILL
-  return INLINE_SYSCALL (tgkill, 3, THREAD_GETMEM (pd, pid), selftid, sig);
+  return INLINE_SYSCALL (tgkill, 3, pid, selftid, sig);
 #else
 # ifdef __NR_tgkill
-  int res = INLINE_SYSCALL (tgkill, 3, THREAD_GETMEM (pd, pid), selftid, sig);
+  int res = INLINE_SYSCALL (tgkill, 3, pid, selftid, sig);
   if (res != -1 || errno != ENOSYS)
     return res;
 # endif