On Fri, Oct 19, 2012 at 09:48:30AM -0700, Kees Cook wrote:
> Mention kfree_rcu() in the call_rcu() section. Additionally fix the
> example code for list replacement that used the wrong structure element.
Good catch! Queued, and thank you for your review and feedback! ;-)
Thanx, Paul
> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
> ---
> Documentation/RCU/listRCU.txt | 2 +-
> Documentation/RCU/whatisRCU.txt | 13 +++++++++++--
> 2 files changed, 12 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/RCU/listRCU.txt b/Documentation/RCU/listRCU.txt
> index 4349c14..adb5a37 100644
> --- a/Documentation/RCU/listRCU.txt
> +++ b/Documentation/RCU/listRCU.txt
> @@ -205,7 +205,7 @@ RCU ("read-copy update") its name. The RCU code is as follows:
> audit_copy_rule(&ne->rule, &e->rule);
> ne->rule.action = newaction;
> 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);
> return 0;
> }
> diff --git a/Documentation/RCU/whatisRCU.txt b/Documentation/RCU/whatisRCU.txt
> index bf0f6de..160ac55 100644
> --- a/Documentation/RCU/whatisRCU.txt
> +++ b/Documentation/RCU/whatisRCU.txt
> @@ -499,6 +499,8 @@ The foo_reclaim() function might appear as follows:
> {
> struct foo *fp = container_of(rp, struct foo, rcu);
>
> + foo_cleanup(fp->a);
> +
> 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
> 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.
>
>
> @@ -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
> 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
> -place of synchronize_rcu().
> +mechanism that never blocks, namely call_rcu() or kfree_rcu(), that can
> +be used in place of synchronize_rcu().
>
>
> 7. FULL LIST OF RCU APIs
> @@ -813,6 +821,7 @@ RCU: Critical sections Grace period Barrier
> rcu_read_unlock synchronize_rcu
> rcu_dereference synchronize_rcu_expedited
> call_rcu
> + kfree_rcu
>
>
> bh: Critical sections Grace period Barrier
> --
> 1.7.9.5
>
>
> --
> Kees Cook
> Chrome OS Security
>
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