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livepatch: Replace synchronize_sched() with synchronize_rcu()

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Now that synchronize_rcu() waits for preempt-disable regions of code
as well as RCU read-side critical sections, synchronize_sched() can be
replaced by synchronize_rcu().  This commit therefore makes this change,
even though it is but a comment.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
This commit is contained in:
Paul E. McKenney 2018-11-07 14:16:57 -08:00
parent 2af3024cd7
commit 6932689e41
2 changed files with 4 additions and 4 deletions
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4
kernel/livepatch/patch.c
View File

@ -61,7 +61,7 @@ static void notrace klp_ftrace_handler(unsigned long ip,
ops = container_of(fops, struct klp_ops, fops); ops = container_of(fops, struct klp_ops, fops);
/* /*
* A variant of synchronize_sched() is used to allow patching functions * A variant of synchronize_rcu() is used to allow patching functions
* where RCU is not watching, see klp_synchronize_transition(). * where RCU is not watching, see klp_synchronize_transition().
*/ */
preempt_disable_notrace(); preempt_disable_notrace();
@ -72,7 +72,7 @@ static void notrace klp_ftrace_handler(unsigned long ip,
/* /*
* func should never be NULL because preemption should be disabled here * func should never be NULL because preemption should be disabled here
* and unregister_ftrace_function() does the equivalent of a * and unregister_ftrace_function() does the equivalent of a
* synchronize_sched() before the func_stack removal. * synchronize_rcu() before the func_stack removal.
*/ */
if (WARN_ON_ONCE(!func)) if (WARN_ON_ONCE(!func))
goto unlock; goto unlock;

4
kernel/livepatch/transition.c
View File

@ -52,7 +52,7 @@ static DECLARE_DELAYED_WORK(klp_transition_work, klp_transition_work_fn);
/* /*
* This function is just a stub to implement a hard force * This function is just a stub to implement a hard force
* of synchronize_sched(). This requires synchronizing * of synchronize_rcu(). This requires synchronizing
* tasks even in userspace and idle. * tasks even in userspace and idle.
*/ */
static void klp_sync(struct work_struct *work) static void klp_sync(struct work_struct *work)
@ -175,7 +175,7 @@ void klp_cancel_transition(void)
void klp_update_patch_state(struct task_struct *task) void klp_update_patch_state(struct task_struct *task)
{ {
/* /*
* A variant of synchronize_sched() is used to allow patching functions * A variant of synchronize_rcu() is used to allow patching functions
* where RCU is not watching, see klp_synchronize_transition(). * where RCU is not watching, see klp_synchronize_transition().
*/ */
preempt_disable_notrace(); preempt_disable_notrace();