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-rw-r--r--Documentation/RCU/whatisRCU.txt13
1 files changed, 11 insertions, 2 deletions
diff --git a/Documentation/RCU/whatisRCU.txt b/Documentation/RCU/whatisRCU.txt
index bf0f6de2aa00..160ac5557e97 100644
--- a/Documentation/RCU/whatisRCU.txt
+++ b/Documentation/RCU/whatisRCU.txt
@@ -499,6 +499,8 @@ The foo_reclaim() function might appear as follows:
499 { 499 {
500 struct foo *fp = container_of(rp, struct foo, rcu); 500 struct foo *fp = container_of(rp, struct foo, rcu);
501 501
502 foo_cleanup(fp->a);
503
502 kfree(fp); 504 kfree(fp);
503 } 505 }
504 506
@@ -521,6 +523,12 @@ o Use call_rcu() -after- removing a data element from an
521 read-side critical sections that might be referencing that 523 read-side critical sections that might be referencing that
522 data item. 524 data item.
523 525
526If the callback for call_rcu() is not doing anything more than calling
527kfree() on the structure, you can use kfree_rcu() instead of call_rcu()
528to avoid having to write your own callback:
529
530 kfree_rcu(old_fp, rcu);
531
524Again, see checklist.txt for additional rules governing the use of RCU. 532Again, see checklist.txt for additional rules governing the use of RCU.
525 533
526 534
@@ -773,8 +781,8 @@ a single atomic update, converting to RCU will require special care.
773 781
774Also, the presence of synchronize_rcu() means that the RCU version of 782Also, the presence of synchronize_rcu() means that the RCU version of
775delete() can now block. If this is a problem, there is a callback-based 783delete() can now block. If this is a problem, there is a callback-based
776mechanism that never blocks, namely call_rcu(), that can be used in 784mechanism that never blocks, namely call_rcu() or kfree_rcu(), that can
777place of synchronize_rcu(). 785be used in place of synchronize_rcu().
778 786
779 787
7807. FULL LIST OF RCU APIs 7887. FULL LIST OF RCU APIs
@@ -813,6 +821,7 @@ RCU: Critical sections Grace period Barrier
813 rcu_read_unlock synchronize_rcu 821 rcu_read_unlock synchronize_rcu
814 rcu_dereference synchronize_rcu_expedited 822 rcu_dereference synchronize_rcu_expedited
815 call_rcu 823 call_rcu
824 kfree_rcu
816 825
817 826
818bh: Critical sections Grace period Barrier 827bh: Critical sections Grace period Barrier