[PATCH RT 11/32] hrtimer: Add a missing bracket and hide `migration_base on !SMP

Steven Rostedt
2020-01-17T17:43:20Z

From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

[ Upstream commit 47b6de0b7f22c28b40275aeede3993d807668c3b ]

[ Upstream commit 5d2295f3a93b04986d069ebeaf5b07725f9096c1 ]

The recent change to avoid taking the expiry lock when a timer is currently
migrated missed to add a bracket at the end of the if statement leading to
compile errors. Since that commit the variable `migration_base' is always
used but it is only available on SMP configuration thus leading to another
compile error. The changelog says "The timer base and base->cpu_base
cannot be NULL in the code path", so it is safe to limit this check to SMP
configurations only.

Add the missing bracket to the if statement and hide `migration_base'
behind CONFIG_SMP bars.

[ tglx: Mark the functions inline ... ]

Fixes: 68b2c8c1e4210 ("hrtimer: Don't take expiry_lock when timer is currently migrated")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190904145527.eah7z56ntwobqm6j@linutronix.de
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
[bigeasy: port back to RT]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
kernel/time/hrtimer.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 1a5167c68310..e54a95de8b79 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -150,6 +150,11 @@ static struct hrtimer_cpu_base migration_cpu_base = {

#define migration_base migration_cpu_base.clock_base[0]

+static inline bool is_migration_base(struct hrtimer_clock_base *base)
+{
+ return base == &migration_base;
+}
+
/*
* We are using hashed locking: holding per_cpu(hrtimer_bases)[n].lock
* means that all timers which are tied to this base via timer->base are
@@ -274,6 +279,11 @@ switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base,

#else /* CONFIG_SMP */

+static inline bool is_migration_base(struct hrtimer_clock_base *base)
+{
+ return false;
+}
+
static inline struct hrtimer_clock_base *
lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
{
@@ -943,7 +953,7 @@ void hrtimer_grab_expiry_lock(const struct hrtimer *timer)
{
struct hrtimer_clock_base *base = READ_ONCE(timer->base);

- if (timer->is_soft && base != &migration_base) {
+ if (timer->is_soft && is_migration_base(base)) {
spin_lock(&base->cpu_base->softirq_expiry_lock);
spin_unlock(&base->cpu_base->softirq_expiry_lock);
}
--
2.24.1