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authorPaul E. McKenney <paulmck@kernel.org>2023-11-25 03:23:56 +0300
committerBoqun Feng <boqun.feng@gmail.com>2024-02-14 18:53:49 +0300
commit3cf501612108b8a7a4cebf8a6ac1d7575080c88f (patch)
treeafaab60db82a5c0454eac18db96687081c7b520a /Documentation/RCU
parent8dbc33b4d1a19ff43930dc983c457946241078e8 (diff)
downloadlinux-3cf501612108b8a7a4cebf8a6ac1d7575080c88f.tar.xz
doc: Make checklist.rst note that spinlocks are implied RCU readers
In kernels built with CONFIG_PREEMPT_RT=n, spinlock critical sections are RCU readers because they disable preemption. However, they are also RCU readers in CONFIG_PREEMPT_RT=y because in that case the locking primitives contain rcu_read_lock() and rcu_read_unlock(). Therefore, upgrade checklist.rst to document this non-obvious case. While in the area, fix a typo by changing "read-side critical" to "read-side critical section". Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Diffstat (limited to 'Documentation/RCU')
-rw-r--r--Documentation/RCU/checklist.rst5
1 files changed, 3 insertions, 2 deletions
diff --git a/Documentation/RCU/checklist.rst b/Documentation/RCU/checklist.rst
index 2d42998a89a6..98a622f77248 100644
--- a/Documentation/RCU/checklist.rst
+++ b/Documentation/RCU/checklist.rst
@@ -68,7 +68,8 @@ over a rather long period of time, but improvements are always welcome!
rcu_read_lock_sched(), or by the appropriate update-side lock.
Explicit disabling of preemption (preempt_disable(), for example)
can serve as rcu_read_lock_sched(), but is less readable and
- prevents lockdep from detecting locking issues.
+ prevents lockdep from detecting locking issues. Acquiring a
+ spinlock also enters an RCU read-side critical section.
Please note that you *cannot* rely on code known to be built
only in non-preemptible kernels. Such code can and will break,
@@ -444,7 +445,7 @@ over a rather long period of time, but improvements are always welcome!
real-time workloads than is synchronize_rcu_expedited().
It is also permissible to sleep in RCU Tasks Trace read-side
- critical, which are delimited by rcu_read_lock_trace() and
+ critical section, which are delimited by rcu_read_lock_trace() and
rcu_read_unlock_trace(). However, this is a specialized flavor
of RCU, and you should not use it without first checking with
its current users. In most cases, you should instead use SRCU.