linux-kernel - [PATCH 6/6] timers/migration: Remove dead code handling idle CPU checking for remote timers

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Message-ID: <20251024132536.39841-7-frederic@kernel.org>
Date: Fri, 24 Oct 2025 15:25:36 +0200
From: Frederic Weisbecker <frederic@...nel.org>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: LKML <linux-kernel@...r.kernel.org>,
	Frederic Weisbecker <frederic@...nel.org>,
	Anna-Maria Behnsen <anna-maria@...utronix.de>
Subject: [PATCH 6/6] timers/migration: Remove dead code handling idle CPU checking for remote timers

Idle migrators don't walk the whole tree in order to find out if there
are timers to migrate because they recorded the next deadline to be
verified within a single check in tmigr_requires_handle_remote().

Remove the related dead code and data.

Signed-off-by: Frederic Weisbecker <frederic@...nel.org>
---
 kernel/time/timer_migration.c | 16 ----------------
 1 file changed, 16 deletions(-)

diff --git a/kernel/time/timer_migration.c b/kernel/time/timer_migration.c
index 73d9b0648116..19ddfa96b9df 100644
--- a/kernel/time/timer_migration.c
+++ b/kernel/time/timer_migration.c
@@ -504,11 +504,6 @@ static bool tmigr_check_lonely(struct tmigr_group *group)
  * @now:		timer base monotonic
  * @check:		is set if there is the need to handle remote timers;
  *			required in tmigr_requires_handle_remote() only
- * @tmc_active:		this flag indicates, whether the CPU which triggers
- *			the hierarchy walk is !idle in the timer migration
- *			hierarchy. When the CPU is idle and the whole hierarchy is
- *			idle, only the first event of the top level has to be
- *			considered.
  */
 struct tmigr_walk {
 	u64			nextexp;
@@ -519,7 +514,6 @@ struct tmigr_walk {
 	unsigned long		basej;
 	u64			now;
 	bool			check;
-	bool			tmc_active;
 };
 
 typedef bool (*up_f)(struct tmigr_group *, struct tmigr_group *, struct tmigr_walk *);
@@ -1119,15 +1113,6 @@ static bool tmigr_requires_handle_remote_up(struct tmigr_group *group,
 	 */
 	if (!tmigr_check_migrator(group, childmask))
 		return true;
-
-	/*
-	 * When there is a parent group and the CPU which triggered the
-	 * hierarchy walk is not active, proceed the walk to reach the top level
-	 * group before reading the next_expiry value.
-	 */
-	if (group->parent && !data->tmc_active)
-		return false;
-
 	/*
 	 * The lock is required on 32bit architectures to read the variable
 	 * consistently with a concurrent writer. On 64bit the lock is not
@@ -1172,7 +1157,6 @@ bool tmigr_requires_handle_remote(void)
 	data.now = get_jiffies_update(&jif);
 	data.childmask = tmc->groupmask;
 	data.firstexp = KTIME_MAX;
-	data.tmc_active = !tmc->idle;
 	data.check = false;
 
 	/*
-- 
2.51.0