Commit 058cc23b authored by Mauro Carvalho Chehab's avatar Mauro Carvalho Chehab Committed by Paul E. McKenney
Browse files

docs: RCU: Convert lockdep.txt to ReST 



- Add a SPDX header;
- Adjust document title;
- Mark literal blocks as such;
- Add it to RCU/index.rst.

Signed-off-by: default avatarMauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent a3b0a79f

Documentation/RCU/index.rst

+1 −0
Original line number Diff line number Diff line
@@ -11,6 +11,7 @@ RCU concepts 


   arrayRCU

   checklist

   lockdep

   lockdep-splat

   rcubarrier

   rcu_dereference

Documentation/RCU/lockdep.txt→Documentation/RCU/lockdep.rst

+8 −4
Original line number Diff line number Diff line 
.. SPDX-License-Identifier: GPL-2.0



========================

RCU and lockdep checking

========================



All flavors of RCU have lockdep checking available, so that lockdep is

aware of when each task enters and leaves any flavor of RCU read-side
@@ -8,7 +12,7 @@ tracking to include RCU state, which can sometimes help when debugging 
deadlocks and the like.



In addition, RCU provides the following primitives that check lockdep's

state:

state::



	rcu_read_lock_held() for normal RCU.

	rcu_read_lock_bh_held() for RCU-bh.
@@ -63,7 +67,7 @@ checking of rcu_dereference() primitives: 
The rcu_dereference_check() check expression can be any boolean

expression, but would normally include a lockdep expression.  However,

any boolean expression can be used.  For a moderately ornate example,

consider the following:

consider the following::



	file = rcu_dereference_check(fdt->fd[fd],

				     lockdep_is_held(&files->file_lock) ||
@@ -82,7 +86,7 @@ RCU read-side critical sections, in case (2) the ->file_lock prevents 
any change from taking place, and finally, in case (3) the current task

is the only task accessing the file_struct, again preventing any change

from taking place.  If the above statement was invoked only from updater

code, it could instead be written as follows:

code, it could instead be written as follows::



	file = rcu_dereference_protected(fdt->fd[fd],

					 lockdep_is_held(&files->file_lock) ||
@@ -105,7 +109,7 @@ false and they are called from outside any RCU read-side critical section. 


For example, the workqueue for_each_pwq() macro is intended to be used

either within an RCU read-side critical section or with wq->mutex held.

It is thus implemented as follows:

It is thus implemented as follows::



	#define for_each_pwq(pwq, wq)

		list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node,

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