From 1ee41680572971e34d90d5f584daf33195ec6dcb Mon Sep 17 00:00:00 2001
From: Stefan Richter <stefanr@s5r6.in-berlin.de>
Date: Thu, 19 Aug 2010 14:13:43 -0700
Subject: Documentation: kernel-locking: mutex_trylock cannot be used in
 interrupt context

Chapter 6 is right about mutex_trylock, but chapter 10 wasn't.  This error
was introduced during semaphore-to-mutex conversion of the Unreliable
guide.  :-)

If user context which performs mutex_lock() or mutex_trylock() is
preempted by interrupt context which performs mutex_trylock() on the same
mutex instance, a deadlock occurs.  This is because these functions do not
disable local IRQs when they operate on mutex->wait_lock.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 Documentation/DocBook/kernel-locking.tmpl | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

(limited to 'Documentation/DocBook')

diff --git a/Documentation/DocBook/kernel-locking.tmpl b/Documentation/DocBook/kernel-locking.tmpl
index 084f6ad7b7a0..0b1a3f97f285 100644
--- a/Documentation/DocBook/kernel-locking.tmpl
+++ b/Documentation/DocBook/kernel-locking.tmpl
@@ -1922,9 +1922,12 @@ machines due to caching.
       <function>mutex_lock()</function>
       </para>
       <para>
-       There is a <function>mutex_trylock()</function> which can be
-       used inside interrupt context, as it will not sleep.
+       There is a <function>mutex_trylock()</function> which does not
+       sleep.  Still, it must not be used inside interrupt context since
+       its implementation is not safe for that.
        <function>mutex_unlock()</function> will also never sleep.
+       It cannot be used in interrupt context either since a mutex
+       must be released by the same task that acquired it.
       </para>
      </listitem>
     </itemizedlist>
-- 
cgit v1.2.1


From 7c38875a0d0a9b90eee66be79e36995c86acc70c Mon Sep 17 00:00:00 2001
From: Jason Baron <jbaron@redhat.com>
Date: Thu, 26 Aug 2010 10:35:43 -0400
Subject: workqueue: Add a workqueue chapter to the tracepoint docbook

Add a workqueue chapter to the traceopint docbook.

Current book is at: http://www.kernel.org/doc/htmldocs/tracepoint/

Signed-off-by: Jason Baron <jbaron@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
---
 Documentation/DocBook/tracepoint.tmpl | 5 +++++
 1 file changed, 5 insertions(+)

(limited to 'Documentation/DocBook')

diff --git a/Documentation/DocBook/tracepoint.tmpl b/Documentation/DocBook/tracepoint.tmpl
index e8473eae2a20..b57a9ede3224 100644
--- a/Documentation/DocBook/tracepoint.tmpl
+++ b/Documentation/DocBook/tracepoint.tmpl
@@ -104,4 +104,9 @@
    <title>Block IO</title>
 !Iinclude/trace/events/block.h
   </chapter>
+
+  <chapter id="workqueue">
+   <title>Workqueue</title>
+!Iinclude/trace/events/workqueue.h
+  </chapter>
 </book>
-- 
cgit v1.2.1