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authorRoland McGrath <roland@hack.frob.com>2014-07-07 09:28:38 -0700
committerRoland McGrath <roland@hack.frob.com>2014-07-07 09:28:38 -0700
commit08192659bbeae149e7cb1f4c43547257f7099bb0 (patch)
tree9f602a4e9f0aefdb06bc15a76be46e958e91a58f /nptl/sem_wait.c
parent96baf6ffc57b811bbc424a1fc72ef77dd56d7a18 (diff)
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Get rid of nptl/sysdeps/ entirely!
Diffstat (limited to 'nptl/sem_wait.c')
-rw-r--r--nptl/sem_wait.c123
1 files changed, 123 insertions, 0 deletions
diff --git a/nptl/sem_wait.c b/nptl/sem_wait.c
new file mode 100644
index 0000000000..b12babb596
--- /dev/null
+++ b/nptl/sem_wait.c
@@ -0,0 +1,123 @@
+/* sem_wait -- wait on a semaphore. Generic futex-using version.
+ Copyright (C) 2003-2014 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+ Contributed by Paul Mackerras <paulus@au.ibm.com>, 2003.
+
+ 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
+ <http://www.gnu.org/licenses/>. */
+
+#include <errno.h>
+#include <sysdep.h>
+#include <lowlevellock.h>
+#include <internaltypes.h>
+#include <semaphore.h>
+
+#include <pthreadP.h>
+#include <shlib-compat.h>
+#include <atomic.h>
+
+
+void
+attribute_hidden
+__sem_wait_cleanup (void *arg)
+{
+ struct new_sem *isem = (struct new_sem *) arg;
+
+ atomic_decrement (&isem->nwaiters);
+}
+
+/* This is in a seperate function in order to make sure gcc
+ puts the call site into an exception region, and thus the
+ cleanups get properly run. */
+static int
+__attribute__ ((noinline))
+do_futex_wait (struct new_sem *isem)
+{
+ int err, oldtype = __pthread_enable_asynccancel ();
+
+ err = lll_futex_wait (&isem->value, 0, isem->private ^ FUTEX_PRIVATE_FLAG);
+
+ __pthread_disable_asynccancel (oldtype);
+ return err;
+}
+
+int
+__new_sem_wait (sem_t *sem)
+{
+ struct new_sem *isem = (struct new_sem *) sem;
+ int err;
+
+ if (atomic_decrement_if_positive (&isem->value) > 0)
+ return 0;
+
+ atomic_increment (&isem->nwaiters);
+
+ pthread_cleanup_push (__sem_wait_cleanup, isem);
+
+ while (1)
+ {
+ err = do_futex_wait(isem);
+ if (err != 0 && err != -EWOULDBLOCK)
+ {
+ __set_errno (-err);
+ err = -1;
+ break;
+ }
+
+ if (atomic_decrement_if_positive (&isem->value) > 0)
+ {
+ err = 0;
+ break;
+ }
+ }
+
+ pthread_cleanup_pop (0);
+
+ atomic_decrement (&isem->nwaiters);
+
+ return err;
+}
+versioned_symbol (libpthread, __new_sem_wait, sem_wait, GLIBC_2_1);
+
+
+#if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_1)
+int
+attribute_compat_text_section
+__old_sem_wait (sem_t *sem)
+{
+ int *futex = (int *) sem;
+ int err;
+
+ do
+ {
+ if (atomic_decrement_if_positive (futex) > 0)
+ return 0;
+
+ /* Enable asynchronous cancellation. Required by the standard. */
+ int oldtype = __pthread_enable_asynccancel ();
+
+ /* Always assume the semaphore is shared. */
+ err = lll_futex_wait (futex, 0, LLL_SHARED);
+
+ /* Disable asynchronous cancellation. */
+ __pthread_disable_asynccancel (oldtype);
+ }
+ while (err == 0 || err == -EWOULDBLOCK);
+
+ __set_errno (-err);
+ return -1;
+}
+
+compat_symbol (libpthread, __old_sem_wait, sem_wait, GLIBC_2_0);
+#endif