summaryrefslogtreecommitdiff
path: root/libpthread/nptl/pthread_cancel.c
diff options
context:
space:
mode:
Diffstat (limited to 'libpthread/nptl/pthread_cancel.c')
-rw-r--r--libpthread/nptl/pthread_cancel.c104
1 files changed, 104 insertions, 0 deletions
diff --git a/libpthread/nptl/pthread_cancel.c b/libpthread/nptl/pthread_cancel.c
new file mode 100644
index 000000000..0ea990693
--- /dev/null
+++ b/libpthread/nptl/pthread_cancel.c
@@ -0,0 +1,104 @@
+/* Copyright (C) 2002, 2003, 2004 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, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ 02111-1307 USA. */
+
+#include <errno.h>
+#include <signal.h>
+#include "pthreadP.h"
+#include "atomic.h"
+#include <sysdep.h>
+#include <bits/kernel-features.h>
+
+
+int
+pthread_cancel (th)
+ pthread_t th;
+{
+ volatile struct pthread *pd = (volatile struct pthread *) th;
+
+ /* Make sure the descriptor is valid. */
+ if (INVALID_TD_P (pd))
+ /* Not a valid thread handle. */
+ return ESRCH;
+
+#ifdef SHARED
+ pthread_cancel_init ();
+#endif
+ int result = 0;
+ int oldval;
+ int newval;
+ do
+ {
+ oldval = pd->cancelhandling;
+ newval = oldval | CANCELING_BITMASK | CANCELED_BITMASK;
+
+ /* Avoid doing unnecessary work. The atomic operation can
+ potentially be expensive if the bug has to be locked and
+ remote cache lines have to be invalidated. */
+ if (oldval == newval)
+ break;
+
+ /* If the cancellation is handled asynchronously just send a
+ signal. We avoid this if possible since it's more
+ expensive. */
+ if (CANCEL_ENABLED_AND_CANCELED_AND_ASYNCHRONOUS (newval))
+ {
+ /* Mark the cancellation as "in progress". */
+ atomic_bit_set (&pd->cancelhandling, CANCELING_BIT);
+
+ /* The cancellation handler will take care of marking the
+ 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,
+ THREAD_GETMEM (THREAD_SELF, pid), pd->tid,
+ SIGCANCEL);
+#else
+# ifdef __NR_tgkill
+ val = INTERNAL_SYSCALL (tgkill, err, 3,
+ THREAD_GETMEM (THREAD_SELF, pid), pd->tid,
+ SIGCANCEL);
+ if (INTERNAL_SYSCALL_ERROR_P (val, err)
+ && INTERNAL_SYSCALL_ERRNO (val, err) == ENOSYS)
+# endif
+ val = INTERNAL_SYSCALL (tkill, err, 2, pd->tid, SIGCANCEL);
+#endif
+
+ if (INTERNAL_SYSCALL_ERROR_P (val, err))
+ result = INTERNAL_SYSCALL_ERRNO (val, err);
+
+ break;
+ }
+ }
+ /* Mark the thread as canceled. This has to be done
+ atomically since other bits could be modified as well. */
+ while (atomic_compare_and_exchange_bool_acq (&pd->cancelhandling, newval,
+ oldval));
+
+ return result;
+}
+
+PTHREAD_STATIC_FN_REQUIRE (pthread_create)