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>
diff --git a/arch/m68k/kernel/Makefile b/arch/m68k/kernel/Makefile
index a806208..7a62a71 100644
--- a/arch/m68k/kernel/Makefile
+++ b/arch/m68k/kernel/Makefile
@@ -10,7 +10,7 @@
extra-y += vmlinux.lds
obj-y := entry.o process.o traps.o ints.o signal.o ptrace.o module.o \
- sys_m68k.o time.o semaphore.o setup.o m68k_ksyms.o devres.o
+ sys_m68k.o time.o setup.o m68k_ksyms.o devres.o
devres-y = ../../../kernel/irq/devres.o
diff --git a/arch/m68k/kernel/m68k_ksyms.c b/arch/m68k/kernel/m68k_ksyms.c
index 6fc69c7..d900e77 100644
--- a/arch/m68k/kernel/m68k_ksyms.c
+++ b/arch/m68k/kernel/m68k_ksyms.c
@@ -1,5 +1,4 @@
#include <linux/module.h>
-#include <asm/semaphore.h>
asmlinkage long long __ashldi3 (long long, int);
asmlinkage long long __ashrdi3 (long long, int);
@@ -15,8 +14,3 @@
EXPORT_SYMBOL(__lshrdi3);
EXPORT_SYMBOL(__muldi3);
-EXPORT_SYMBOL(__down_failed);
-EXPORT_SYMBOL(__down_failed_interruptible);
-EXPORT_SYMBOL(__down_failed_trylock);
-EXPORT_SYMBOL(__up_wakeup);
-
diff --git a/arch/m68k/kernel/semaphore.c b/arch/m68k/kernel/semaphore.c
deleted file mode 100644
index d12cbbf..0000000
--- a/arch/m68k/kernel/semaphore.c
+++ /dev/null
@@ -1,132 +0,0 @@
-/*
- * Generic semaphore code. Buyer beware. Do your own
- * specific changes in <asm/semaphore-helper.h>
- */
-
-#include <linux/sched.h>
-#include <linux/init.h>
-#include <asm/semaphore-helper.h>
-
-#ifndef CONFIG_RMW_INSNS
-spinlock_t semaphore_wake_lock;
-#endif
-
-/*
- * Semaphores are implemented using a two-way counter:
- * The "count" variable is decremented for each process
- * that tries to sleep, while the "waking" variable is
- * incremented when the "up()" code goes to wake up waiting
- * processes.
- *
- * Notably, the inline "up()" and "down()" functions can
- * efficiently test if they need to do any extra work (up
- * needs to do something only if count was negative before
- * the increment operation.
- *
- * waking_non_zero() (from asm/semaphore.h) must execute
- * atomically.
- *
- * When __up() is called, the count was negative before
- * incrementing it, and we need to wake up somebody.
- *
- * This routine adds one to the count of processes that need to
- * wake up and exit. ALL waiting processes actually wake up but
- * only the one that gets to the "waking" field first will gate
- * through and acquire the semaphore. The others will go back
- * to sleep.
- *
- * Note that these functions are only called when there is
- * contention on the lock, and as such all this is the
- * "non-critical" part of the whole semaphore business. The
- * critical part is the inline stuff in <asm/semaphore.h>
- * where we want to avoid any extra jumps and calls.
- */
-void __up(struct semaphore *sem)
-{
- wake_one_more(sem);
- wake_up(&sem->wait);
-}
-
-/*
- * Perform the "down" function. Return zero for semaphore acquired,
- * return negative for signalled out of the function.
- *
- * If called from __down, the return is ignored and the wait loop is
- * not interruptible. This means that a task waiting on a semaphore
- * using "down()" cannot be killed until someone does an "up()" on
- * the semaphore.
- *
- * If called from __down_interruptible, the return value gets checked
- * upon return. If the return value is negative then the task continues
- * with the negative value in the return register (it can be tested by
- * the caller).
- *
- * Either form may be used in conjunction with "up()".
- *
- */
-
-
-#define DOWN_HEAD(task_state) \
- \
- \
- current->state = (task_state); \
- add_wait_queue(&sem->wait, &wait); \
- \
- /* \
- * Ok, we're set up. sem->count is known to be less than zero \
- * so we must wait. \
- * \
- * We can let go the lock for purposes of waiting. \
- * We re-acquire it after awaking so as to protect \
- * all semaphore operations. \
- * \
- * If "up()" is called before we call waking_non_zero() then \
- * we will catch it right away. If it is called later then \
- * we will have to go through a wakeup cycle to catch it. \
- * \
- * Multiple waiters contend for the semaphore lock to see \
- * who gets to gate through and who has to wait some more. \
- */ \
- for (;;) {
-
-#define DOWN_TAIL(task_state) \
- current->state = (task_state); \
- } \
- current->state = TASK_RUNNING; \
- remove_wait_queue(&sem->wait, &wait);
-
-void __sched __down(struct semaphore * sem)
-{
- DECLARE_WAITQUEUE(wait, current);
-
- DOWN_HEAD(TASK_UNINTERRUPTIBLE)
- if (waking_non_zero(sem))
- break;
- schedule();
- DOWN_TAIL(TASK_UNINTERRUPTIBLE)
-}
-
-int __sched __down_interruptible(struct semaphore * sem)
-{
- DECLARE_WAITQUEUE(wait, current);
- int ret = 0;
-
- DOWN_HEAD(TASK_INTERRUPTIBLE)
-
- ret = waking_non_zero_interruptible(sem, current);
- if (ret)
- {
- if (ret == 1)
- /* ret != 0 only if we get interrupted -arca */
- ret = 0;
- break;
- }
- schedule();
- DOWN_TAIL(TASK_INTERRUPTIBLE)
- return ret;
-}
-
-int __down_trylock(struct semaphore * sem)
-{
- return waking_non_zero_trylock(sem);
-}
diff --git a/arch/m68k/lib/Makefile b/arch/m68k/lib/Makefile
index 6bbf19f..a18af09 100644
--- a/arch/m68k/lib/Makefile
+++ b/arch/m68k/lib/Makefile
@@ -5,4 +5,4 @@
EXTRA_AFLAGS := -traditional
lib-y := ashldi3.o ashrdi3.o lshrdi3.o muldi3.o \
- checksum.o string.o semaphore.o uaccess.o
+ checksum.o string.o uaccess.o
diff --git a/arch/m68k/lib/semaphore.S b/arch/m68k/lib/semaphore.S
deleted file mode 100644
index 0215624c..0000000
--- a/arch/m68k/lib/semaphore.S
+++ /dev/null
@@ -1,53 +0,0 @@
-/*
- * linux/arch/m68k/lib/semaphore.S
- *
- * Copyright (C) 1996 Linus Torvalds
- *
- * m68k version by Andreas Schwab
- */
-
-#include <linux/linkage.h>
-#include <asm/semaphore.h>
-
-/*
- * The semaphore operations have a special calling sequence that
- * allow us to do a simpler in-line version of them. These routines
- * need to convert that sequence back into the C sequence when
- * there is contention on the semaphore.
- */
-ENTRY(__down_failed)
- moveml %a0/%d0/%d1,-(%sp)
- movel %a1,-(%sp)
- jbsr __down
- movel (%sp)+,%a1
- moveml (%sp)+,%a0/%d0/%d1
- rts
-
-ENTRY(__down_failed_interruptible)
- movel %a0,-(%sp)
- movel %d1,-(%sp)
- movel %a1,-(%sp)
- jbsr __down_interruptible
- movel (%sp)+,%a1
- movel (%sp)+,%d1
- movel (%sp)+,%a0
- rts
-
-ENTRY(__down_failed_trylock)
- movel %a0,-(%sp)
- movel %d1,-(%sp)
- movel %a1,-(%sp)
- jbsr __down_trylock
- movel (%sp)+,%a1
- movel (%sp)+,%d1
- movel (%sp)+,%a0
- rts
-
-ENTRY(__up_wakeup)
- moveml %a0/%d0/%d1,-(%sp)
- movel %a1,-(%sp)
- jbsr __up
- movel (%sp)+,%a1
- moveml (%sp)+,%a0/%d0/%d1
- rts
-