Commit 79ea7f43 authored by Wei Yang's avatar Wei Yang Committed by Joel Fernandes
Browse files

doc/RCU/listRCU: refine example code for eliminating stale data 



This patch adjust the example code with following two purpose:

  * reduce the confusion on not releasing e->lock
  * emphasize e is valid and not stale with e->lock held

Signed-off-by: default avatarWei Yang <richard.weiyang@gmail.com>
CC: Boqun Feng <boqun.feng@gmail.com>
CC: Alan Huang <mmpgouride@gmail.com>
Reviewed-by: default avatarAlan Huang <mmpgouride@gmail.com>
Link: https://lore.kernel.org/r/20250218005047.27258-1-richard.weiyang@gmail.com


Signed-off-by: default avatarBoqun Feng <boqun.feng@gmail.com>
Signed-off-by: default avatarJoel Fernandes <joelagnelf@nvidia.com>
parent 1708bf2c

Documentation/RCU/listRCU.rst

+6 −4
Original line number Diff line number Diff line
@@ -334,7 +334,7 @@ If the system-call audit module were to ever need to reject stale data, one way 
to accomplish this would be to add a ``deleted`` flag and a ``lock`` spinlock to the

``audit_entry`` structure, and modify audit_filter_task() as follows::



	static enum audit_state audit_filter_task(struct task_struct *tsk)

	static struct audit_entry *audit_filter_task(struct task_struct *tsk, char **key)

	{

		struct audit_entry *e;

		enum audit_state   state;
@@ -346,16 +346,18 @@ to accomplish this would be to add a ``deleted`` flag and a ``lock`` spinlock to 
				if (e->deleted) {

					spin_unlock(&e->lock);

					rcu_read_unlock();

					return AUDIT_BUILD_CONTEXT;

					return NULL;

				}

				rcu_read_unlock();

				if (state == AUDIT_STATE_RECORD)

					*key = kstrdup(e->rule.filterkey, GFP_ATOMIC);

				return state;

				/* As long as e->lock is held, e is valid and

				 * its value is not stale */

				return e;

			}

		}

		rcu_read_unlock();

		return AUDIT_BUILD_CONTEXT;

		return NULL;

	}



The ``audit_del_rule()`` function would need to set the ``deleted`` flag under the