projects/linux·commit 66656ebb

docs: kernel-locking: Convert semaphore references

66656ebb · Daniel Walker <[email protected]> · 2008-02-06 01:37:39 -08:00

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 <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Commit
66656ebb5bf3f94aaeca1fbd369672bba980babf
Parents
ec5b1157

Changes

1 files changed · +16 −16

FileStatusAddDelContent
Documentation/DocBook/kernel-locking.tmplmodified+16−16View file

Documentation/DocBook/kernel-locking.tmpl

View file
diff --git a/Documentation/DocBook/kernel-locking.tmpl b/Documentation/DocBook/kernel-locking.tmpl
index 01825ee..2e9d6b4 100644
--- a/Documentation/DocBook/kernel-locking.tmpl
+++ b/Documentation/DocBook/kernel-locking.tmpl
@@ -717,7 +717,7 @@ used, and when it gets full, throws out the least used one.
<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 &lt;linux/list.h&gt;
#include &lt;linux/slab.h&gt;
#include &lt;linux/string.h&gt;
-#include &lt;asm/semaphore.h&gt;
+#include &lt;linux/mutex.h&gt;
#include &lt;asm/errno.h&gt;
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-&gt;id = id;
obj-&gt;popularity = 0;
- down(&amp;cache_lock);
+ mutex_lock(&amp;cache_lock);
__cache_add(obj);
- up(&amp;cache_lock);
+ mutex_unlock(&amp;cache_lock);
return 0;
}
void cache_delete(int id)
{
- down(&amp;cache_lock);
+ mutex_lock(&amp;cache_lock);
__cache_delete(__cache_find(id));
- up(&amp;cache_lock);
+ mutex_unlock(&amp;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(&amp;cache_lock);
+ mutex_lock(&amp;cache_lock);
obj = __cache_find(id);
if (obj) {
ret = 0;
strcpy(name, obj-&gt;name);
}
- up(&amp;cache_lock);
+ mutex_unlock(&amp;cache_lock);
return ret;
}
</programlisting>
@@ -853,7 +853,7 @@ The change is shown below, in standard patch format: the
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 patch format: the
obj-&gt;id = id;
obj-&gt;popularity = 0;
-- down(&amp;cache_lock);
+- mutex_lock(&amp;cache_lock);
+ spin_lock_irqsave(&amp;cache_lock, flags);
__cache_add(obj);
-- up(&amp;cache_lock);
+- mutex_unlock(&amp;cache_lock);
+ spin_unlock_irqrestore(&amp;cache_lock, flags);
return 0;
}
void cache_delete(int id)
{
-- down(&amp;cache_lock);
+- mutex_lock(&amp;cache_lock);
+ unsigned long flags;
+
+ spin_lock_irqsave(&amp;cache_lock, flags);
__cache_delete(__cache_find(id));
-- up(&amp;cache_lock);
+- mutex_unlock(&amp;cache_lock);
+ spin_unlock_irqrestore(&amp;cache_lock, flags);
}
@@ -895,14 +895,14 @@ The change is shown below, in standard patch format: the
int ret = -ENOENT;
+ unsigned long flags;
-- down(&amp;cache_lock);
+- mutex_lock(&amp;cache_lock);
+ spin_lock_irqsave(&amp;cache_lock, flags);
obj = __cache_find(id);
if (obj) {
ret = 0;
strcpy(name, obj-&gt;name);
}
-- up(&amp;cache_lock);
+- mutex_unlock(&amp;cache_lock);
+ spin_unlock_irqrestore(&amp;cache_lock, flags);
return ret;
}