leandrof/linux
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

doc: Update removal of RCU-bh/sched update machinery

Browse Source 
The RCU-bh update API is now defined in terms of that of RCU-bh and
RCU-sched, so this commit updates the documentation accordingly.

In addition, although RCU-sched persists in !PREEMPT kernels, in
the PREEMPT case its update API is now defined in terms of that of
RCU-preempt, so this commit also updates the documentation accordingly.

While in the area, this commit removes the documentation for the
now-obsolete synchronize_rcu_mult() and clarifies the Tasks RCU
documentation.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney
2018-07-02 08:25:57 -07:00
parent ea24c125fe
commit 77095901b8
7 changed files with 61 additions and 152 deletions
Download Patch File Download Diff File Expand all files Collapse all files

23
Documentation/RCU/Design/Data-Structures/Data-Structures.html
View File

@@ -1374,8 +1374,7 @@ that is, if the CPU is currently idle.
Accessor Functions</a></h3>
<p>The following listing shows the
<tt>rcu_get_root()</tt>, <tt>rcu_for_each_node_breadth_first</tt>,
<tt>rcu_for_each_nonleaf_node_breadth_first()</tt>, and
<tt>rcu_get_root()</tt>, <tt>rcu_for_each_node_breadth_first</tt> and
<tt>rcu_for_each_leaf_node()</tt> function and macros:
<pre>
@@ -1388,13 +1387,9 @@ Accessor Functions</a></h3>
7 for ((rnp) = &amp;(rsp)-&gt;node[0]; \
8 (rnp) &lt; &amp;(rsp)-&gt;node[NUM_RCU_NODES]; (rnp)++)
9
10 #define rcu_for_each_nonleaf_node_breadth_first(rsp, rnp) \
11 for ((rnp) = &amp;(rsp)-&gt;node[0]; \
12 (rnp) &lt; (rsp)-&gt;level[NUM_RCU_LVLS - 1]; (rnp)++)
13
14 #define rcu_for_each_leaf_node(rsp, rnp) \
15 for ((rnp) = (rsp)-&gt;level[NUM_RCU_LVLS - 1]; \
16 (rnp) &lt; &amp;(rsp)-&gt;node[NUM_RCU_NODES]; (rnp)++)
10 #define rcu_for_each_leaf_node(rsp, rnp) \
11 for ((rnp) = (rsp)-&gt;level[NUM_RCU_LVLS - 1]; \
12 (rnp) &lt; &amp;(rsp)-&gt;node[NUM_RCU_NODES]; (rnp)++)
</pre>
<p>The <tt>rcu_get_root()</tt> simply returns a pointer to the
@@ -1407,10 +1402,7 @@ macro takes advantage of the layout of the <tt>rcu_node</tt>
structures in the <tt>rcu_state</tt> structure's
<tt>-&gt;node[]</tt> array, performing a breadth-first traversal by
simply traversing the array in order.
The <tt>rcu_for_each_nonleaf_node_breadth_first()</tt> macro operates
similarly, but traverses only the first part of the array, thus excluding
the leaf <tt>rcu_node</tt> structures.
Finally, the <tt>rcu_for_each_leaf_node()</tt> macro traverses only
Similarly, the <tt>rcu_for_each_leaf_node()</tt> macro traverses only
the last part of the array, thus traversing only the leaf
<tt>rcu_node</tt> structures.
@@ -1418,15 +1410,14 @@ the last part of the array, thus traversing only the leaf
<tr><th>&nbsp;</th></tr>
<tr><th align="left">Quick Quiz:</th></tr>
<tr><td>
What do <tt>rcu_for_each_nonleaf_node_breadth_first()</tt> and
What does
<tt>rcu_for_each_leaf_node()</tt> do if the <tt>rcu_node</tt> tree
contains only a single node?
</td></tr>
<tr><th align="left">Answer:</th></tr>
<tr><td bgcolor="#ffffff"><font color="ffffff">
In the single-node case,
<tt>rcu_for_each_nonleaf_node_breadth_first()</tt> is a no-op
and <tt>rcu_for_each_leaf_node()</tt> traverses the single node.
<tt>rcu_for_each_leaf_node()</tt> traverses the single node.
</font></td></tr>
<tr><td>&nbsp;</td></tr>
</table>