2 files changed, 31 insertions, 14 deletions

diff --git a/Documentation/DocBook/kernel-locking.tmpl b/Documentation/DocBook/kernel-locking.tmpl
index 77c42f40be5d..2510763295d0 100644
--- a/Documentation/DocBook/kernel-locking.tmpl
+++ b/Documentation/DocBook/kernel-locking.tmpl
@@ -703,6 +703,31 @@
 </sect1>
 </chapter>
 
+<chapter id="trylock-functions">
+ <title>The trylock Functions</title>
+  <para>
+   There are functions that try to acquire a lock only once and immediately
+   return a value telling about success or failure to acquire the lock.
+   They can be used if you need no access to the data protected with the lock
+   when some other thread is holding the lock. You should acquire the lock
+   later if you then need access to the data protected with the lock.
+  </para>
+
+  <para>
+    <function>spin_trylock()</function> does not spin but returns non-zero if
+    it acquires the spinlock on the first try or 0 if not. This function can
+    be used in all contexts like <function>spin_lock</function>: you must have
+    disabled the contexts that might interrupt you and acquire the spin lock.
+  </para>
+
+  <para>
+    <function>mutex_trylock()</function> does not suspend your task
+    but returns non-zero if it could lock the mutex on the first try
+    or 0 if not. This function cannot be safely used in hardware or software
+    interrupt contexts despite not sleeping.
+  </para>
+</chapter>
+
   <chapter id="Examples">
    <title>Common Examples</title>
     <para>
diff --git a/Documentation/DocBook/kgdb.tmpl b/Documentation/DocBook/kgdb.tmpl
index 028a8444d95e..e8acd1f03456 100644
--- a/Documentation/DocBook/kgdb.tmpl
+++ b/Documentation/DocBook/kgdb.tmpl
@@ -84,10 +84,9 @@
     runs an instance of gdb against the vmlinux file which contains
     the symbols (not boot image such as bzImage, zImage, uImage...).
     In gdb the developer specifies the connection parameters and
-    connects to kgdb.  Depending on which kgdb I/O modules exist in
-    the kernel for a given architecture, it may be possible to debug
-    the test machine's kernel with the development machine using a
-    rs232 or ethernet connection.
+    connects to kgdb.  The type of connection a developer makes with
+    gdb depends on the availability of kgdb I/O modules compiled as
+    builtin's or kernel modules in the test machine's kernel.
     </para>
   </chapter>
   <chapter id="CompilingAKernel">
@@ -223,7 +222,7 @@
   </para>
   <para>
   IMPORTANT NOTE: Using this option with kgdb over the console
-  (kgdboc) or kgdb over ethernet (kgdboe) is not supported.
+  (kgdboc) is not supported.
   </para>
   </sect1>
   </chapter>
@@ -249,18 +248,11 @@
     (gdb) target remote /dev/ttyS0
     </programlisting>
     <para>
-    Example (kgdb to a terminal server):
+    Example (kgdb to a terminal server on tcp port 2012):
     </para>
     <programlisting>
     % gdb ./vmlinux
-    (gdb) target remote udp:192.168.2.2:6443
-    </programlisting>
-    <para>
-    Example (kgdb over ethernet):
-    </para>
-    <programlisting>
-    % gdb ./vmlinux
-    (gdb) target remote udp:192.168.2.2:6443
+    (gdb) target remote 192.168.2.2:2012
     </programlisting>
     <para>
     Once connected, you can debug a kernel the way you would debug an