diff mbox series

[5.10,088/103] srcu: Provide internal interface to start a Tiny SRCU grace period

Message ID 20210901122303.496935499@linuxfoundation.org
State New
Headers show
Series None | expand

Commit Message

Greg KH Sept. 1, 2021, 12:28 p.m. UTC 
From: Paul E. McKenney <paulmck@kernel.org>

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@moria.home.lan/
Reported-by: Kent Overstreet <kent.overstreet@gmail.com>
Reviewed-by: Neeraj Upadhyay <neeraju@codeaurora.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 kernel/rcu/srcutiny.c |   17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)
diff mbox series

Patch

--- 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);