diff options
Diffstat (limited to 'Documentation/DocBook/kernel-locking.tmpl')
| -rw-r--r-- | Documentation/DocBook/kernel-locking.tmpl | 27 |
1 files changed, 15 insertions, 12 deletions
diff --git a/Documentation/DocBook/kernel-locking.tmpl b/Documentation/DocBook/kernel-locking.tmpl index 084f6ad7b7a..f66f4df1869 100644 --- a/Documentation/DocBook/kernel-locking.tmpl +++ b/Documentation/DocBook/kernel-locking.tmpl @@ -1645,7 +1645,9 @@ the amount of locking which needs to be done. all the readers who were traversing the list when we deleted the element are finished. We use <function>call_rcu()</function> to register a callback which will actually destroy the object once - the readers are finished. + all pre-existing readers are finished. Alternatively, + <function>synchronize_rcu()</function> may be used to block until + all pre-existing are finished. </para> <para> But how does Read Copy Update know when the readers are @@ -1714,7 +1716,7 @@ the amount of locking which needs to be done. - object_put(obj); + list_del_rcu(&obj->list); cache_num--; -+ call_rcu(&obj->rcu, cache_delete_rcu, obj); ++ call_rcu(&obj->rcu, cache_delete_rcu); } /* Must be holding cache_lock */ @@ -1725,14 +1727,6 @@ the amount of locking which needs to be done. if (++cache_num > MAX_CACHE_SIZE) { struct object *i, *outcast = NULL; list_for_each_entry(i, &cache, list) { -@@ -85,6 +94,7 @@ - obj->popularity = 0; - atomic_set(&obj->refcnt, 1); /* The cache holds a reference */ - spin_lock_init(&obj->lock); -+ INIT_RCU_HEAD(&obj->rcu); - - spin_lock_irqsave(&cache_lock, flags); - __cache_add(obj); @@ -104,12 +114,11 @@ struct object *cache_find(int id) { @@ -1922,9 +1916,12 @@ 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> @@ -1958,6 +1955,12 @@ machines due to caching. </sect1> </chapter> + <chapter id="apiref"> + <title>Mutex API reference</title> +!Iinclude/linux/mutex.h +!Ekernel/mutex.c + </chapter> + <chapter id="references"> <title>Further reading</title> |