This is a note to let you know that I've just added the patch titled
srcu: Provide internal interface to start a Tiny SRCU grace period
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
srcu-provide-internal-interface-to-start-a-tiny-srcu-grace-period.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 1a893c711a600ab57526619b56e6f6b7be00956e Mon Sep 17 00:00:00 2001
From: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
Date: Fri, 13 Nov 2020 09:37:39 -0800
Subject: srcu: Provide internal interface to start a Tiny SRCU grace period
From: Paul E. McKenney <paulmck@xxxxxxxxxx>
commit 1a893c711a600ab57526619b56e6f6b7be00956e upstream.
There is a need for a polling interface for SRCU grace periods.
This polling needs to initiate an SRCU grace period without
having to queue (and manage) a callback. This commit therefore
splits the Tiny SRCU call_srcu() function into callback-queuing and
start-grace-period portions, with the latter in a new function named
srcu_gp_start_if_needed().
Link: https://lore.kernel.org/rcu/20201112201547.GF3365678@xxxxxxxxxxxxxx/
Reported-by: Kent Overstreet <kent.overstreet@xxxxxxxxx>
Reviewed-by: Neeraj Upadhyay <neeraju@xxxxxxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/rcu/srcutiny.c | 17 +++++++++++------
1 file changed, 11 insertions(+), 6 deletions(-)
--- a/kernel/rcu/srcutiny.c
+++ b/kernel/rcu/srcutiny.c
@@ -151,6 +151,16 @@ void srcu_drive_gp(struct work_struct *w
}
EXPORT_SYMBOL_GPL(srcu_drive_gp);
+static void srcu_gp_start_if_needed(struct srcu_struct *ssp)
+{
+ if (!READ_ONCE(ssp->srcu_gp_running)) {
+ if (likely(srcu_init_done))
+ schedule_work(&ssp->srcu_work);
+ else if (list_empty(&ssp->srcu_work.entry))
+ list_add(&ssp->srcu_work.entry, &srcu_boot_list);
+ }
+}
+
/*
* Enqueue an SRCU callback on the specified srcu_struct structure,
* initiating grace-period processing if it is not already running.
@@ -166,12 +176,7 @@ void call_srcu(struct srcu_struct *ssp,
*ssp->srcu_cb_tail = rhp;
ssp->srcu_cb_tail = &rhp->next;
local_irq_restore(flags);
- if (!READ_ONCE(ssp->srcu_gp_running)) {
- if (likely(srcu_init_done))
- schedule_work(&ssp->srcu_work);
- else if (list_empty(&ssp->srcu_work.entry))
- list_add(&ssp->srcu_work.entry, &srcu_boot_list);
- }
+ srcu_gp_start_if_needed(ssp);
}
EXPORT_SYMBOL_GPL(call_srcu);
Patches currently in stable-queue which might be from paulmck@xxxxxxxxxx are
queue-5.10/srcu-provide-polling-interfaces-for-tiny-srcu-grace-periods.patch
queue-5.10/tracepoint-use-rcu-get-state-and-cond-sync-for-static-call-updates.patch
queue-5.10/srcu-provide-internal-interface-to-start-a-tiny-srcu-grace-period.patch
queue-5.10/srcu-provide-polling-interfaces-for-tree-srcu-grace-periods.patch
queue-5.10/srcu-provide-internal-interface-to-start-a-tree-srcu-grace-period.patch
queue-5.10/srcu-make-tiny-srcu-use-multi-bit-grace-period-counter.patch
