On Mon, Aug 19, 2024 at 12:59:31PM -0400, Kent Overstreet wrote:
> this assertion appears to have been entirely unnecessary
>
> Signed-off-by: Kent Overstreet <kent.overstr...@linux.dev>
Please also adjust the comments. Or just take this from the -rcu tree's
"dev" branch, which is shown at the end of this email:
e0a917e08b9b ("rcu: Permit start_poll_synchronize_rcu*() with interrupts
disabled")
> ---
> kernel/rcu/tree.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index e641cc681901..52f9f0bf1b8e 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -4119,7 +4119,6 @@ static void start_poll_synchronize_rcu_common(void)
> struct rcu_data *rdp;
> struct rcu_node *rnp;
>
> - lockdep_assert_irqs_enabled();
> local_irq_save(flags);
> rdp = this_cpu_ptr(&rcu_data);
> rnp = rdp->mynode;
> --
> 2.45.2
>
------------------------------------------------------------------------
commit e0a917e08b9b39eee5870738250d0b8b10272dbe
Author: Paul E. McKenney <paul...@kernel.org>
Date: Fri Aug 16 14:22:48 2024 -0700
rcu: Permit start_poll_synchronize_rcu*() with interrupts disabled
The header comment for both start_poll_synchronize_rcu() and
start_poll_synchronize_rcu_full() state that interrupts must be enabled
when calling these two functions, and there is a lockdep assertion in
start_poll_synchronize_rcu_common() enforcing this restriction. However,
there is no need for this restrictions, as can be seen in call_rcu(),
which does wakeups when interrupts are disabled.
This commit therefore removes the lockdep assertion and the comments.
Reported-by: Kent Overstreet <kent.overstr...@linux.dev>
Signed-off-by: Paul E. McKenney <paul...@kernel.org>
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 36b207918158c..47c753ae9bbcd 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -4103,7 +4103,6 @@ static void start_poll_synchronize_rcu_common(void)
struct rcu_data *rdp;
struct rcu_node *rnp;
- lockdep_assert_irqs_enabled();
local_irq_save(flags);
rdp = this_cpu_ptr(&rcu_data);
rnp = rdp->mynode;
@@ -4128,9 +4127,6 @@ static void start_poll_synchronize_rcu_common(void)
* grace period has elapsed in the meantime. If the needed grace period
* is not already slated to start, notifies RCU core of the need for that
* grace period.
- *
- * Interrupts must be enabled for the case where it is necessary to awaken
- * the grace-period kthread.
*/
unsigned long start_poll_synchronize_rcu(void)
{
@@ -4151,9 +4147,6 @@ EXPORT_SYMBOL_GPL(start_poll_synchronize_rcu);
* grace period (whether normal or expedited) has elapsed in the meantime.
* If the needed grace period is not already slated to start, notifies
* RCU core of the need for that grace period.
- *
- * Interrupts must be enabled for the case where it is necessary to awaken
- * the grace-period kthread.
*/
void start_poll_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp)
{
