anierin/msm-5.15
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

ANDROID: fix ABI breakage in struct psi_group

Browse Source 
New atomic member addition into struct psi_group breaks ABI. Fix the
breakage by reusing poll_wakeup atomic and using atomic bit operations
to represent both wakeup and scheduled states.

Bug: 251702862
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Change-Id: I6c25d756bd7afafe8590373f16a662d02bf15b50
This commit is contained in:
Suren Baghdasaryan
2022-10-07 13:01:27 -07:00
parent 9ed7219990
commit 2455f6610a
2 changed files with 36 additions and 9 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
include/linux/psi_types.h
View File

@@ -142,6 +142,11 @@ struct psi_trigger {
u64 last_event_time;
};
enum poll_wakeup_bits {
POLL_WAKEUP = 0,
POLL_SCHEDULED = 1,
};
struct psi_group {
/* Protects data used by the aggregator */
struct mutex avgs_lock;
@@ -166,7 +171,6 @@ struct psi_group {
struct timer_list poll_timer;
wait_queue_head_t poll_wait;
atomic_t poll_wakeup;
atomic_t poll_scheduled;
/* Protects data used by the monitor */
struct mutex trigger_lock;

39
kernel/sched/psi.c
View File

@@ -191,6 +191,28 @@ static void psi_avgs_work(struct work_struct *work);
static void poll_timer_fn(struct timer_list *t);
static inline void atomic_set_bit(int i, atomic_t *v)
{
atomic_or(1 << i, v);
}
static inline void atomic_clear_bit(int i, atomic_t *v)
{
atomic_and(~(1 << i), v);
}
static inline int atomic_fetch_and_set_bit(int i, atomic_t *v)
{
int mask = 1 << i;
return atomic_fetch_or(mask, v) & mask;
}
static inline int atomic_fetch_and_clear_bit(int i, atomic_t *v)
{
int mask = 1 << i;
return atomic_fetch_and(~mask, v) & mask;
}
static void group_init(struct psi_group *group)
{
int cpu;
@@ -202,7 +224,7 @@ static void group_init(struct psi_group *group)
INIT_DELAYED_WORK(&group->avgs_work, psi_avgs_work);
mutex_init(&group->avgs_lock);
/* Init trigger-related members */
atomic_set(&group->poll_scheduled, 0);
atomic_set(&group->poll_wakeup, 0);
mutex_init(&group->trigger_lock);
INIT_LIST_HEAD(&group->triggers);
memset(group->nr_triggers, 0, sizeof(group->nr_triggers));
@@ -577,7 +599,8 @@ static void psi_schedule_poll_work(struct psi_group *group, unsigned long delay,
* atomic_xchg should be called even when !force to provide a
* full memory barrier (see the comment inside psi_poll_work).
*/
if (atomic_xchg(&group->poll_scheduled, 1) && !force)
if (atomic_fetch_and_set_bit(POLL_SCHEDULED, &group->poll_wakeup) &&
!force)
return;
rcu_read_lock();
@@ -590,7 +613,7 @@ static void psi_schedule_poll_work(struct psi_group *group, unsigned long delay,
if (likely(task))
mod_timer(&group->poll_timer, jiffies + delay);
else
atomic_set(&group->poll_scheduled, 0);
atomic_clear_bit(POLL_SCHEDULED, &group->poll_wakeup);
rcu_read_unlock();
}
@@ -615,7 +638,7 @@ static void psi_poll_work(struct psi_group *group)
* should be negligible and polling_next_update still keeps
* updates correctly on schedule.
*/
atomic_set(&group->poll_scheduled, 0);
atomic_clear_bit(POLL_SCHEDULED, &group->poll_wakeup);
/*
* A task change can race with the poll worker that is supposed to
* report on it. To avoid missing events, ensure ordering between
@@ -682,7 +705,7 @@ static int psi_poll_worker(void *data)
while (true) {
wait_event_interruptible(group->poll_wait,
atomic_cmpxchg(&group->poll_wakeup, 1, 0) ||
atomic_fetch_and_clear_bit(POLL_WAKEUP, &group->poll_wakeup) ||
kthread_should_stop());
if (kthread_should_stop())
break;
@@ -696,7 +719,7 @@ static void poll_timer_fn(struct timer_list *t)
{
struct psi_group *group = from_timer(group, t, poll_timer);
atomic_set(&group->poll_wakeup, 1);
atomic_set_bit(POLL_WAKEUP, &group->poll_wakeup);
wake_up_interruptible(&group->poll_wait);
}
@@ -1177,7 +1200,7 @@ struct psi_trigger *psi_trigger_create(struct psi_group *group,
mutex_unlock(&group->trigger_lock);
return ERR_CAST(task);
}
atomic_set(&group->poll_wakeup, 0);
atomic_clear_bit(POLL_WAKEUP, &group->poll_wakeup);
wake_up_process(task);
rcu_assign_pointer(group->poll_task, task);
}
@@ -1256,7 +1279,7 @@ void psi_trigger_destroy(struct psi_trigger *t)
* can no longer be found through group->poll_task.
*/
kthread_stop(task_to_destroy);
atomic_set(&group->poll_scheduled, 0);
atomic_clear_bit(POLL_SCHEDULED, &group->poll_wakeup);
}
kfree(t);
}