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rcu: Update docs to include kfree_rcu() 

Mention kfree_rcu() in the call_rcu() section.  Additionally fix the
example code for list replacement that used the wrong structure element.

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
hifive-unleashed-5.1
Kees Cook 2012-10-19 09:48:30 -07:00 committed by Paul E. McKenney
parent 0f9574d832
commit 57d34a6cee
2 changed files with 12 additions and 3 deletions
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2
Documentation/RCU/listRCU.txt
View File

@ -205,7 +205,7 @@ RCU ("read-copy update") its name. The RCU code is as follows:
audit_copy_rule(&ne->rule, &e->rule); audit_copy_rule(&ne->rule, &e->rule);
ne->rule.action = newaction; ne->rule.action = newaction;
ne->rule.file_count = newfield_count; ne->rule.file_count = newfield_count;
list_replace_rcu(e, ne); list_replace_rcu(&e->list, &ne->list);
call_rcu(&e->rcu, audit_free_rule); call_rcu(&e->rcu, audit_free_rule);
return 0; return 0;
} }

13
Documentation/RCU/whatisRCU.txt
View File

@ -499,6 +499,8 @@ The foo_reclaim() function might appear as follows:
{ {
struct foo *fp = container_of(rp, struct foo, rcu); struct foo *fp = container_of(rp, struct foo, rcu);
foo_cleanup(fp->a);
kfree(fp); kfree(fp);
} }
@ -521,6 +523,12 @@ o Use call_rcu() -after- removing a data element from an
read-side critical sections that might be referencing that read-side critical sections that might be referencing that
data item. data item.
If the callback for call_rcu() is not doing anything more than calling
kfree() on the structure, you can use kfree_rcu() instead of call_rcu()
to avoid having to write your own callback:
kfree_rcu(old_fp, rcu);
Again, see checklist.txt for additional rules governing the use of RCU. Again, see checklist.txt for additional rules governing the use of RCU.
@ -773,8 +781,8 @@ a single atomic update, converting to RCU will require special care.
Also, the presence of synchronize_rcu() means that the RCU version of Also, the presence of synchronize_rcu() means that the RCU version of
delete() can now block. If this is a problem, there is a callback-based delete() can now block. If this is a problem, there is a callback-based
mechanism that never blocks, namely call_rcu(), that can be used in mechanism that never blocks, namely call_rcu() or kfree_rcu(), that can
place of synchronize_rcu(). be used in place of synchronize_rcu().
7. FULL LIST OF RCU APIs 7. FULL LIST OF RCU APIs
@ -813,6 +821,7 @@ RCU: Critical sections Grace period Barrier
rcu_read_unlock synchronize_rcu rcu_read_unlock synchronize_rcu
rcu_dereference synchronize_rcu_expedited rcu_dereference synchronize_rcu_expedited
call_rcu call_rcu
kfree_rcu
bh: Critical sections Grace period Barrier bh: Critical sections Grace period Barrier