Mutex documentation is unclear about software interrupts, tasklets and timers

Acked-by: NArjan van de Ven <arjan@linux.intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Documentation/mutex-design.txt

@@ -90,7 +90,8 @@ of advantages of mutexes:
    * - task may not exit with mutex held
    * - memory areas where held locks reside must not be freed
    * - held mutexes must not be reinitialized
-   * - mutexes may not be used in irq contexts
+   * - mutexes may not be used in hardware or software interrupt
+   *   contexts such as tasklets and timers
 
    furthermore, there are also convenience features in the debugging
    code:

include/linux/mutex.h

@@ -29,7 +29,8 @@
  * - task may not exit with mutex held
  * - memory areas where held locks reside must not be freed
  * - held mutexes must not be reinitialized
- * - mutexes may not be used in irq contexts
+ * - mutexes may not be used in hardware or software interrupt
+ *   contexts such as tasklets and timers
  *
  * These semantics are fully enforced when DEBUG_MUTEXES is
  * enabled. Furthermore, besides enforcing the above rules, the mutex