-The semaphore code has four funcs
down,
down_interruptible,
down_killable,
down_timeout
-These four funcs have almost similar code except that
they all call lower level function __down_xyz.
-This lower level func in-turn call inline func
__down_common with appropriate arguments.
-This patch creates a common macro for above family of funcs
so that duplicate code is eliminated.
-Also, __down_common has been made noinline so that code is
functionally similar to previous one
-For example, earlier down_killable would call __down_killable
, which in-turn would call inline func __down_common
Now, down_killable calls noinline __down_common directly
through a macro
-The funcs __down_interruptible, __down_killable etc have been
removed as they were just wrapper to __down_common
Signed-off-by: Satendra Singh Thakur <satendrasingh.tha...@hcl.com>
---
v1: removed disclaimer appended automatically by company mail policy
kernel/locking/semaphore.c | 107 +++++++++++++------------------------
1 file changed, 38 insertions(+), 69 deletions(-)
diff --git a/kernel/locking/semaphore.c b/kernel/locking/semaphore.c
index d9dd94defc0a..0468bc335908 100644
--- a/kernel/locking/semaphore.c
+++ b/kernel/locking/semaphore.c
@@ -33,11 +33,33 @@
#include <linux/spinlock.h>
#include <linux/ftrace.h>
-static noinline void __down(struct semaphore *sem);
-static noinline int __down_interruptible(struct semaphore *sem);
-static noinline int __down_killable(struct semaphore *sem);
-static noinline int __down_timeout(struct semaphore *sem, long timeout);
+static noinline int __sched __down_common(struct semaphore *sem, long state,
+ long timeout);
static noinline void __up(struct semaphore *sem);
+/**
+ * down_common - acquire the semaphore
+ * @sem: the semaphore to be acquired
+ * @state: new state of the task
+ * @timeout: either MAX_SCHEDULE_TIMEOUT or actual specified
+ * timeout
+ * Acquires the semaphore. If no more tasks are allowed to
+ * acquire the semaphore, calling this macro will put the task
+ * to sleep until the semaphore is released.
+ *
+ * This internally calls another func __down_common.
+ */
+#define down_common(sem, state, timeout) \
+({ \
+ int ret = 0; \
+ unsigned long flags; \
+ raw_spin_lock_irqsave(&(sem)->lock, flags); \
+ if (likely((sem)->count > 0)) \
+ (sem)->count--; \
+ else \
+ ret = __down_common(sem, state, timeout); \
+ raw_spin_unlock_irqrestore(&(sem)->lock, flags); \
+ ret; \
+})
/**
* down - acquire the semaphore
@@ -52,14 +74,7 @@ static noinline void __up(struct semaphore *sem);
*/
void down(struct semaphore *sem)
{
- unsigned long flags;
-
- raw_spin_lock_irqsave(&sem->lock, flags);
- if (likely(sem->count > 0))
- sem->count--;
- else
- __down(sem);
- raw_spin_unlock_irqrestore(&sem->lock, flags);
+ down_common(sem, TASK_UNINTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
}
EXPORT_SYMBOL(down);
@@ -74,17 +89,7 @@ EXPORT_SYMBOL(down);
*/
int down_interruptible(struct semaphore *sem)
{
- unsigned long flags;
- int result = 0;
-
- raw_spin_lock_irqsave(&sem->lock, flags);
- if (likely(sem->count > 0))
- sem->count--;
- else
- result = __down_interruptible(sem);
- raw_spin_unlock_irqrestore(&sem->lock, flags);
-
- return result;
+ return down_common(sem, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
}
EXPORT_SYMBOL(down_interruptible);
@@ -100,17 +105,7 @@ EXPORT_SYMBOL(down_interruptible);
*/
int down_killable(struct semaphore *sem)
{
- unsigned long flags;
- int result = 0;
-
- raw_spin_lock_irqsave(&sem->lock, flags);
- if (likely(sem->count > 0))
- sem->count--;
- else
- result = __down_killable(sem);
- raw_spin_unlock_irqrestore(&sem->lock, flags);
-
- return result;
+ return down_common(sem, TASK_KILLABLE, MAX_SCHEDULE_TIMEOUT);
}
EXPORT_SYMBOL(down_killable);
@@ -154,17 +149,7 @@ EXPORT_SYMBOL(down_trylock);
*/
int down_timeout(struct semaphore *sem, long timeout)
{
- unsigned long flags;
- int result = 0;
-
- raw_spin_lock_irqsave(&sem->lock, flags);
- if (likely(sem->count > 0))
- sem->count--;
- else
- result = __down_timeout(sem, timeout);
- raw_spin_unlock_irqrestore(&sem->lock, flags);
-
- return result;
+ return down_common(sem, TASK_UNINTERRUPTIBLE, timeout);
}
EXPORT_SYMBOL(down_timeout);
@@ -196,12 +181,15 @@ struct semaphore_waiter {
bool up;
};
-/*
- * Because this function is inlined, the 'state' parameter will be
- * constant, and thus optimised away by the compiler. Likewise the
- * 'timeout' parameter for the cases without timeouts.
+/**
+ * __down_common - Adds the current task to wait list
+ * puts the task to sleep until signal, timeout or up flag
+ * @sem: the semaphore to be acquired
+ * @state: the state of the calling task
+ * @timeout: either MAX_SCHEDULE_TIMEOUT or actual specified
+ * timeout
*/
-static inline int __sched __down_common(struct semaphore *sem, long state,
+static noinline int __sched __down_common(struct semaphore *sem, long state,
long timeout)
{
struct semaphore_waiter waiter;
@@ -232,25 +220,6 @@ static inline int __sched __down_common(struct semaphore
*sem, long state,
return -EINTR;
}
-static noinline void __sched __down(struct semaphore *sem)
-{
- __down_common(sem, TASK_UNINTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
-}
-
-static noinline int __sched __down_interruptible(struct semaphore *sem)
-{
- return __down_common(sem, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
-}
-
-static noinline int __sched __down_killable(struct semaphore *sem)
-{
- return __down_common(sem, TASK_KILLABLE, MAX_SCHEDULE_TIMEOUT);
-}
-
-static noinline int __sched __down_timeout(struct semaphore *sem, long timeout)
-{
- return __down_common(sem, TASK_UNINTERRUPTIBLE, timeout);
-}
static noinline void __sched __up(struct semaphore *sem)
{
--
2.17.1
