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author | Russell King <rmk@dyn-67.arm.linux.org.uk> | 2008-04-19 16:17:34 (GMT) |
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committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2008-04-19 16:17:34 (GMT) |
commit | cf816ecb533ab96b883dfdc0db174598b5b5c4d2 (patch) | |
tree | 1b7705db288ae2917105e624b01fdf81e0882bf1 /arch/sh/kernel/semaphore.c | |
parent | adf6d34e460387ee3e8f1e1875d52bff51212c7d (diff) | |
parent | 15f7d677ccff6f0f5de8a1ee43a792567e9f9de9 (diff) | |
download | linux-fsl-qoriq-cf816ecb533ab96b883dfdc0db174598b5b5c4d2.tar.xz |
Merge branch 'merge-fixes' into devel
Diffstat (limited to 'arch/sh/kernel/semaphore.c')
-rw-r--r-- | arch/sh/kernel/semaphore.c | 139 |
1 files changed, 0 insertions, 139 deletions
diff --git a/arch/sh/kernel/semaphore.c b/arch/sh/kernel/semaphore.c deleted file mode 100644 index 184119e..0000000 --- a/arch/sh/kernel/semaphore.c +++ /dev/null @@ -1,139 +0,0 @@ -/* - * Just taken from alpha implementation. - * This can't work well, perhaps. - */ -/* - * Generic semaphore code. Buyer beware. Do your own - * specific changes in <asm/semaphore-helper.h> - */ - -#include <linux/errno.h> -#include <linux/sched.h> -#include <linux/wait.h> -#include <linux/init.h> -#include <asm/semaphore.h> -#include <asm/semaphore-helper.h> - -DEFINE_SPINLOCK(semaphore_wake_lock); - -/* - * 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_VAR \ - struct task_struct *tsk = current; \ - wait_queue_t wait; \ - init_waitqueue_entry(&wait, tsk); - -#define DOWN_HEAD(task_state) \ - \ - \ - tsk->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) \ - tsk->state = (task_state); \ - } \ - tsk->state = TASK_RUNNING; \ - remove_wait_queue(&sem->wait, &wait); - -void __sched __down(struct semaphore * sem) -{ - DOWN_VAR - DOWN_HEAD(TASK_UNINTERRUPTIBLE) - if (waking_non_zero(sem)) - break; - schedule(); - DOWN_TAIL(TASK_UNINTERRUPTIBLE) -} - -int __sched __down_interruptible(struct semaphore * sem) -{ - int ret = 0; - DOWN_VAR - DOWN_HEAD(TASK_INTERRUPTIBLE) - - ret = waking_non_zero_interruptible(sem, tsk); - 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); -} |