The patch titled
docs: kernel-locking: Convert semaphore references
has been removed from the -mm tree. Its filename was
docs-kernel-locking-convert-semaphore-references.patch
This patch was dropped because it was merged into mainline or a subsystem tree
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: docs: kernel-locking: Convert semaphore references
From: Daniel Walker <dwalker@xxxxxxxxxx>
I converted some of the document to reflect mutex usage instead of
semaphore usage. Since we shouldin't be promoting semaphore usage when
it's on it's way out..
Signed-off-by: Daniel Walker <dwalker@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/DocBook/kernel-locking.tmpl | 32 ++++++++++----------
1 file changed, 16 insertions(+), 16 deletions(-)
diff -puN Documentation/DocBook/kernel-locking.tmpl~docs-kernel-locking-convert-semaphore-references Documentation/DocBook/kernel-locking.tmpl
--- a/Documentation/DocBook/kernel-locking.tmpl~docs-kernel-locking-convert-semaphore-references
+++ a/Documentation/DocBook/kernel-locking.tmpl
@@ -717,7 +717,7 @@ used, and when it gets full, throws out
<para>
For our first example, we assume that all operations are in user
context (ie. from system calls), so we can sleep. This means we can
-use a semaphore to protect the cache and all the objects within
+use a mutex to protect the cache and all the objects within
it. Here's the code:
</para>
@@ -725,7 +725,7 @@ it. Here's the code:
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/string.h>
-#include <asm/semaphore.h>
+#include <linux/mutex.h>
#include <asm/errno.h>
struct object
@@ -737,7 +737,7 @@ struct object
};
/* Protects the cache, cache_num, and the objects within it */
-static DECLARE_MUTEX(cache_lock);
+static DEFINE_MUTEX(cache_lock);
static LIST_HEAD(cache);
static unsigned int cache_num = 0;
#define MAX_CACHE_SIZE 10
@@ -789,17 +789,17 @@ int cache_add(int id, const char *name)
obj->id = id;
obj->popularity = 0;
- down(&cache_lock);
+ mutex_lock(&cache_lock);
__cache_add(obj);
- up(&cache_lock);
+ mutex_unlock(&cache_lock);
return 0;
}
void cache_delete(int id)
{
- down(&cache_lock);
+ mutex_lock(&cache_lock);
__cache_delete(__cache_find(id));
- up(&cache_lock);
+ mutex_unlock(&cache_lock);
}
int cache_find(int id, char *name)
@@ -807,13 +807,13 @@ int cache_find(int id, char *name)
struct object *obj;
int ret = -ENOENT;
- down(&cache_lock);
+ mutex_lock(&cache_lock);
obj = __cache_find(id);
if (obj) {
ret = 0;
strcpy(name, obj->name);
}
- up(&cache_lock);
+ mutex_unlock(&cache_lock);
return ret;
}
</programlisting>
@@ -853,7 +853,7 @@ The change is shown below, in standard p
int popularity;
};
--static DECLARE_MUTEX(cache_lock);
+-static DEFINE_MUTEX(cache_lock);
+static spinlock_t cache_lock = SPIN_LOCK_UNLOCKED;
static LIST_HEAD(cache);
static unsigned int cache_num = 0;
@@ -870,22 +870,22 @@ The change is shown below, in standard p
obj->id = id;
obj->popularity = 0;
-- down(&cache_lock);
+- mutex_lock(&cache_lock);
+ spin_lock_irqsave(&cache_lock, flags);
__cache_add(obj);
-- up(&cache_lock);
+- mutex_unlock(&cache_lock);
+ spin_unlock_irqrestore(&cache_lock, flags);
return 0;
}
void cache_delete(int id)
{
-- down(&cache_lock);
+- mutex_lock(&cache_lock);
+ unsigned long flags;
+
+ spin_lock_irqsave(&cache_lock, flags);
__cache_delete(__cache_find(id));
-- up(&cache_lock);
+- mutex_unlock(&cache_lock);
+ spin_unlock_irqrestore(&cache_lock, flags);
}
@@ -895,14 +895,14 @@ The change is shown below, in standard p
int ret = -ENOENT;
+ unsigned long flags;
-- down(&cache_lock);
+- mutex_lock(&cache_lock);
+ spin_lock_irqsave(&cache_lock, flags);
obj = __cache_find(id);
if (obj) {
ret = 0;
strcpy(name, obj->name);
}
-- up(&cache_lock);
+- mutex_unlock(&cache_lock);
+ spin_unlock_irqrestore(&cache_lock, flags);
return ret;
}
_
Patches currently in -mm which might be from dwalker@xxxxxxxxxx are
origin.patch
driver-base-memory-semaphore-to-mutex.patch
usb-microtek-remove-unused-semaphore.patch
usb-libusual-locking-cleanup.patch
profile-likely-unlikely-macros.patch
profile-likely-unlikely-macros-fix.patch
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