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authorMatthew Wilcox <matthew@wil.cx>2008-03-07 21:55:58 -0500
committerMatthew Wilcox <willy@linux.intel.com>2008-04-17 10:42:34 -0400
commit64ac24e738823161693bf791f87adc802cf529ff (patch)
tree19c0b0cf314d4394ca580c05b86cdf874ce0a167 /arch/s390
parente48b3deee475134585eed03e7afebe4bf9e0dba9 (diff)
Generic semaphore implementation
Semaphores are no longer performance-critical, so a generic C implementation is better for maintainability, debuggability and extensibility. Thanks to Peter Zijlstra for fixing the lockdep warning. Thanks to Harvey Harrison for pointing out that the unlikely() was unnecessary. Signed-off-by: Matthew Wilcox <willy@linux.intel.com> Acked-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/s390')
-rw-r--r--arch/s390/kernel/Makefile2
-rw-r--r--arch/s390/kernel/s390_ksyms.c7
-rw-r--r--arch/s390/kernel/semaphore.c108
3 files changed, 1 insertions, 116 deletions
diff --git a/arch/s390/kernel/Makefile b/arch/s390/kernel/Makefile
index 4d3e38392cb..ce144b67f06 100644
--- a/arch/s390/kernel/Makefile
+++ b/arch/s390/kernel/Makefile
@@ -11,7 +11,7 @@ CFLAGS_smp.o := -Wno-nonnull
obj-y := bitmap.o traps.o time.o process.o base.o early.o \
setup.o sys_s390.o ptrace.o signal.o cpcmd.o ebcdic.o \
- semaphore.o s390_ext.o debug.o irq.o ipl.o dis.o diag.o
+ s390_ext.o debug.o irq.o ipl.o dis.o diag.o
obj-y += $(if $(CONFIG_64BIT),entry64.o,entry.o)
obj-y += $(if $(CONFIG_64BIT),reipl64.o,reipl.o)
diff --git a/arch/s390/kernel/s390_ksyms.c b/arch/s390/kernel/s390_ksyms.c
index 7234c737f82..48238a114ce 100644
--- a/arch/s390/kernel/s390_ksyms.c
+++ b/arch/s390/kernel/s390_ksyms.c
@@ -27,13 +27,6 @@ EXPORT_SYMBOL(_zb_findmap);
EXPORT_SYMBOL(_sb_findmap);
/*
- * semaphore ops
- */
-EXPORT_SYMBOL(__up);
-EXPORT_SYMBOL(__down);
-EXPORT_SYMBOL(__down_interruptible);
-
-/*
* binfmt_elf loader
*/
extern int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs);
diff --git a/arch/s390/kernel/semaphore.c b/arch/s390/kernel/semaphore.c
deleted file mode 100644
index 191303f6c1d..00000000000
--- a/arch/s390/kernel/semaphore.c
+++ /dev/null
@@ -1,108 +0,0 @@
-/*
- * linux/arch/s390/kernel/semaphore.c
- *
- * S390 version
- * Copyright (C) 1998-2000 IBM Corporation
- * Author(s): Martin Schwidefsky
- *
- * Derived from "linux/arch/i386/kernel/semaphore.c
- * Copyright (C) 1999, Linus Torvalds
- *
- */
-#include <linux/sched.h>
-#include <linux/errno.h>
-#include <linux/init.h>
-
-#include <asm/semaphore.h>
-
-/*
- * Atomically update sem->count. Equivalent to:
- * old_val = sem->count.counter;
- * new_val = ((old_val >= 0) ? old_val : 0) + incr;
- * sem->count.counter = new_val;
- * return old_val;
- */
-static inline int __sem_update_count(struct semaphore *sem, int incr)
-{
- int old_val, new_val;
-
- asm volatile(
- " l %0,0(%3)\n"
- "0: ltr %1,%0\n"
- " jhe 1f\n"
- " lhi %1,0\n"
- "1: ar %1,%4\n"
- " cs %0,%1,0(%3)\n"
- " jl 0b\n"
- : "=&d" (old_val), "=&d" (new_val), "=m" (sem->count)
- : "a" (&sem->count), "d" (incr), "m" (sem->count)
- : "cc");
- return old_val;
-}
-
-/*
- * The inline function up() incremented count but the result
- * was <= 0. This indicates that some process is waiting on
- * the semaphore. The semaphore is free and we'll wake the
- * first sleeping process, so we set count to 1 unless some
- * other cpu has called up in the meantime in which case
- * we just increment count by 1.
- */
-void __up(struct semaphore *sem)
-{
- __sem_update_count(sem, 1);
- wake_up(&sem->wait);
-}
-
-/*
- * The inline function down() decremented count and the result
- * was < 0. The wait loop will atomically test and update the
- * semaphore counter following the rules:
- * count > 0: decrement count, wake up queue and exit.
- * count <= 0: set count to -1, go to sleep.
- */
-void __sched __down(struct semaphore * sem)
-{
- struct task_struct *tsk = current;
- DECLARE_WAITQUEUE(wait, tsk);
-
- __set_task_state(tsk, TASK_UNINTERRUPTIBLE);
- add_wait_queue_exclusive(&sem->wait, &wait);
- while (__sem_update_count(sem, -1) <= 0) {
- schedule();
- set_task_state(tsk, TASK_UNINTERRUPTIBLE);
- }
- remove_wait_queue(&sem->wait, &wait);
- __set_task_state(tsk, TASK_RUNNING);
- wake_up(&sem->wait);
-}
-
-/*
- * Same as __down() with an additional test for signals.
- * If a signal is pending the count is updated as follows:
- * count > 0: wake up queue and exit.
- * count <= 0: set count to 0, wake up queue and exit.
- */
-int __sched __down_interruptible(struct semaphore * sem)
-{
- int retval = 0;
- struct task_struct *tsk = current;
- DECLARE_WAITQUEUE(wait, tsk);
-
- __set_task_state(tsk, TASK_INTERRUPTIBLE);
- add_wait_queue_exclusive(&sem->wait, &wait);
- while (__sem_update_count(sem, -1) <= 0) {
- if (signal_pending(current)) {
- __sem_update_count(sem, 0);
- retval = -EINTR;
- break;
- }
- schedule();
- set_task_state(tsk, TASK_INTERRUPTIBLE);
- }
- remove_wait_queue(&sem->wait, &wait);
- __set_task_state(tsk, TASK_RUNNING);
- wake_up(&sem->wait);
- return retval;
-}
-