Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input

[pandora-kernel.git] / Documentation / DocBook / kernel-locking.tmpl

diff --git a/Documentation/DocBook/kernel-locking.tmpl b/Documentation/DocBook/kernel-locking.tmpl
index 158ffe9..2e9d6b4 100644 (file)
--- a/Documentation/DocBook/kernel-locking.tmpl
+++ b/Documentation/DocBook/kernel-locking.tmpl
@@ -219,7 +219,7 @@
    </para>
 
    <sect1 id="lock-intro">
-   <title>Two Main Types of Kernel Locks: Spinlocks and Semaphores</title>
+   <title>Three Main Types of Kernel Locks: Spinlocks, Mutexes and Semaphores</title>
 
    <para>
      There are three main types of kernel locks.  The fundamental type
@@ -551,10 +551,12 @@
        <function>spin_lock_irqsave()</function>, which is a superset
        of all other spinlock primitives.
    </para>
+
    <table>
 <title>Table of Locking Requirements</title>
 <tgroup cols="11">
 <tbody>
+
 <row>
 <entry></entry>
 <entry>IRQ Handler A</entry>
@@ -576,97 +578,128 @@
 
 <row>
 <entry>IRQ Handler B</entry>
-<entry>spin_lock_irqsave</entry>
+<entry>SLIS</entry>
 <entry>None</entry>
 </row>
 
 <row>
 <entry>Softirq A</entry>
-<entry>spin_lock_irq</entry>
-<entry>spin_lock_irq</entry>
-<entry>spin_lock</entry>
+<entry>SLI</entry>
+<entry>SLI</entry>
+<entry>SL</entry>
 </row>
 
 <row>
 <entry>Softirq B</entry>
-<entry>spin_lock_irq</entry>
-<entry>spin_lock_irq</entry>
-<entry>spin_lock</entry>
-<entry>spin_lock</entry>
+<entry>SLI</entry>
+<entry>SLI</entry>
+<entry>SL</entry>
+<entry>SL</entry>
 </row>
 
 <row>
 <entry>Tasklet A</entry>
-<entry>spin_lock_irq</entry>
-<entry>spin_lock_irq</entry>
-<entry>spin_lock</entry>
-<entry>spin_lock</entry>
+<entry>SLI</entry>
+<entry>SLI</entry>
+<entry>SL</entry>
+<entry>SL</entry>
 <entry>None</entry>
 </row>
 
 <row>
 <entry>Tasklet B</entry>
-<entry>spin_lock_irq</entry>
-<entry>spin_lock_irq</entry>
-<entry>spin_lock</entry>
-<entry>spin_lock</entry>
-<entry>spin_lock</entry>
+<entry>SLI</entry>
+<entry>SLI</entry>
+<entry>SL</entry>
+<entry>SL</entry>
+<entry>SL</entry>
 <entry>None</entry>
 </row>
 
 <row>
 <entry>Timer A</entry>
-<entry>spin_lock_irq</entry>
-<entry>spin_lock_irq</entry>
-<entry>spin_lock</entry>
-<entry>spin_lock</entry>
-<entry>spin_lock</entry>
-<entry>spin_lock</entry>
+<entry>SLI</entry>
+<entry>SLI</entry>
+<entry>SL</entry>
+<entry>SL</entry>
+<entry>SL</entry>
+<entry>SL</entry>
 <entry>None</entry>
 </row>
 
 <row>
 <entry>Timer B</entry>
-<entry>spin_lock_irq</entry>
-<entry>spin_lock_irq</entry>
-<entry>spin_lock</entry>
-<entry>spin_lock</entry>
-<entry>spin_lock</entry>
-<entry>spin_lock</entry>
-<entry>spin_lock</entry>
+<entry>SLI</entry>
+<entry>SLI</entry>
+<entry>SL</entry>
+<entry>SL</entry>
+<entry>SL</entry>
+<entry>SL</entry>
+<entry>SL</entry>
 <entry>None</entry>
 </row>
 
 <row>
 <entry>User Context A</entry>
-<entry>spin_lock_irq</entry>
-<entry>spin_lock_irq</entry>
-<entry>spin_lock_bh</entry>
-<entry>spin_lock_bh</entry>
-<entry>spin_lock_bh</entry>
-<entry>spin_lock_bh</entry>
-<entry>spin_lock_bh</entry>
-<entry>spin_lock_bh</entry>
+<entry>SLI</entry>
+<entry>SLI</entry>
+<entry>SLBH</entry>
+<entry>SLBH</entry>
+<entry>SLBH</entry>
+<entry>SLBH</entry>
+<entry>SLBH</entry>
+<entry>SLBH</entry>
 <entry>None</entry>
 </row>
 
 <row>
 <entry>User Context B</entry>
+<entry>SLI</entry>
+<entry>SLI</entry>
+<entry>SLBH</entry>
+<entry>SLBH</entry>
+<entry>SLBH</entry>
+<entry>SLBH</entry>
+<entry>SLBH</entry>
+<entry>SLBH</entry>
+<entry>DI</entry>
+<entry>None</entry>
+</row>
+
+</tbody>
+</tgroup>
+</table>
+
+   <table>
+<title>Legend for Locking Requirements Table</title>
+<tgroup cols="2">
+<tbody>
+
+<row>
+<entry>SLIS</entry>
+<entry>spin_lock_irqsave</entry>
+</row>
+<row>
+<entry>SLI</entry>
 <entry>spin_lock_irq</entry>
-<entry>spin_lock_irq</entry>
-<entry>spin_lock_bh</entry>
-<entry>spin_lock_bh</entry>
-<entry>spin_lock_bh</entry>
-<entry>spin_lock_bh</entry>
-<entry>spin_lock_bh</entry>
+</row>
+<row>
+<entry>SL</entry>
+<entry>spin_lock</entry>
+</row>
+<row>
+<entry>SLBH</entry>
 <entry>spin_lock_bh</entry>
+</row>
+<row>
+<entry>DI</entry>
 <entry>down_interruptible</entry>
-<entry>None</entry>
 </row>
 
 </tbody>
 </tgroup>
 </table>
+
 </sect1>
 </chapter>
 
@@ -684,7 +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>
 
@@ -692,7 +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
@@ -704,7 +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
@@ -756,17 +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)
@@ -774,13 +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>
@@ -820,7 +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;
@@ -837,22 +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);
  }
 
@@ -862,14 +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;
  }
@@ -1590,7 +1623,7 @@ the amount of locking which needs to be done.
     <para>
       Our final dilemma is this: when can we actually destroy the
       removed element?  Remember, a reader might be stepping through
-      this element in the list right now: it we free this element and
+      this element in the list right now: if we free this element and
       the <symbol>next</symbol> pointer changes, the reader will jump
       off into garbage and crash.  We need to wait until we know that
       all the readers who were traversing the list when we deleted the