From 66656ebb5bf3f94aaeca1fbd369672bba980babf Mon Sep 17 00:00:00 2001 From: Daniel Walker Date: Wed, 6 Feb 2008 01:37:39 -0800 Subject: docs: kernel-locking: Convert semaphore references 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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/DocBook/kernel-locking.tmpl | 32 +++++++++++++++---------------- 1 file changed, 16 insertions(+), 16 deletions(-) (limited to 'Documentation/DocBook') diff --git a/Documentation/DocBook/kernel-locking.tmpl b/Documentation/DocBook/kernel-locking.tmpl index 01825ee7db64..2e9d6b41f034 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. 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: @@ -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; } @@ -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->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 patch format: the 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; } -- cgit v1.2.3