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

From: Frederic Weisbecker
Date: Fri Oct 24 2025 - 09:29:34 EST


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@xxxxxxxxxx>
---
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