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Diffstat (limited to 'kernel')
-rw-r--r--kernel/time/timekeeping.c10
-rw-r--r--kernel/workqueue.c110
2 files changed, 94 insertions, 26 deletions
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 0c1485e42be6..34e5eac81424 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -428,7 +428,7 @@ int do_settimeofday(const struct timespec *tv)
struct timespec ts_delta, xt;
unsigned long flags;
- if (!timespec_valid(tv))
+ if (!timespec_valid_strict(tv))
return -EINVAL;
write_seqlock_irqsave(&tk->lock, flags);
@@ -476,7 +476,7 @@ int timekeeping_inject_offset(struct timespec *ts)
/* Make sure the proposed value is valid */
tmp = timespec_add(tk_xtime(tk), *ts);
- if (!timespec_valid(&tmp)) {
+ if (!timespec_valid_strict(&tmp)) {
ret = -EINVAL;
goto error;
}
@@ -659,7 +659,7 @@ void __init timekeeping_init(void)
struct timespec now, boot, tmp;
read_persistent_clock(&now);
- if (!timespec_valid(&now)) {
+ if (!timespec_valid_strict(&now)) {
pr_warn("WARNING: Persistent clock returned invalid value!\n"
" Check your CMOS/BIOS settings.\n");
now.tv_sec = 0;
@@ -667,7 +667,7 @@ void __init timekeeping_init(void)
}
read_boot_clock(&boot);
- if (!timespec_valid(&boot)) {
+ if (!timespec_valid_strict(&boot)) {
pr_warn("WARNING: Boot clock returned invalid value!\n"
" Check your CMOS/BIOS settings.\n");
boot.tv_sec = 0;
@@ -713,7 +713,7 @@ static struct timespec timekeeping_suspend_time;
static void __timekeeping_inject_sleeptime(struct timekeeper *tk,
struct timespec *delta)
{
- if (!timespec_valid(delta)) {
+ if (!timespec_valid_strict(delta)) {
printk(KERN_WARNING "__timekeeping_inject_sleeptime: Invalid "
"sleep delta value!\n");
return;
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 692d97628a10..1e1373bcb3e3 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -66,6 +66,7 @@ enum {
/* pool flags */
POOL_MANAGE_WORKERS = 1 << 0, /* need to manage workers */
+ POOL_MANAGING_WORKERS = 1 << 1, /* managing workers */
/* worker flags */
WORKER_STARTED = 1 << 0, /* started */
@@ -652,7 +653,7 @@ static bool need_to_manage_workers(struct worker_pool *pool)
/* Do we have too many workers and should some go away? */
static bool too_many_workers(struct worker_pool *pool)
{
- bool managing = mutex_is_locked(&pool->manager_mutex);
+ bool managing = pool->flags & POOL_MANAGING_WORKERS;
int nr_idle = pool->nr_idle + managing; /* manager is considered idle */
int nr_busy = pool->nr_workers - nr_idle;
@@ -1326,6 +1327,15 @@ static void idle_worker_rebind(struct worker *worker)
/* we did our part, wait for rebind_workers() to finish up */
wait_event(gcwq->rebind_hold, !(worker->flags & WORKER_REBIND));
+
+ /*
+ * rebind_workers() shouldn't finish until all workers passed the
+ * above WORKER_REBIND wait. Tell it when done.
+ */
+ spin_lock_irq(&worker->pool->gcwq->lock);
+ if (!--worker->idle_rebind->cnt)
+ complete(&worker->idle_rebind->done);
+ spin_unlock_irq(&worker->pool->gcwq->lock);
}
/*
@@ -1396,12 +1406,15 @@ retry:
/* set REBIND and kick idle ones, we'll wait for these later */
for_each_worker_pool(pool, gcwq) {
list_for_each_entry(worker, &pool->idle_list, entry) {
+ unsigned long worker_flags = worker->flags;
+
if (worker->flags & WORKER_REBIND)
continue;
- /* morph UNBOUND to REBIND */
- worker->flags &= ~WORKER_UNBOUND;
- worker->flags |= WORKER_REBIND;
+ /* morph UNBOUND to REBIND atomically */
+ worker_flags &= ~WORKER_UNBOUND;
+ worker_flags |= WORKER_REBIND;
+ ACCESS_ONCE(worker->flags) = worker_flags;
idle_rebind.cnt++;
worker->idle_rebind = &idle_rebind;
@@ -1419,25 +1432,15 @@ retry:
goto retry;
}
- /*
- * All idle workers are rebound and waiting for %WORKER_REBIND to
- * be cleared inside idle_worker_rebind(). Clear and release.
- * Clearing %WORKER_REBIND from this foreign context is safe
- * because these workers are still guaranteed to be idle.
- */
- for_each_worker_pool(pool, gcwq)
- list_for_each_entry(worker, &pool->idle_list, entry)
- worker->flags &= ~WORKER_REBIND;
-
- wake_up_all(&gcwq->rebind_hold);
-
- /* rebind busy workers */
+ /* all idle workers are rebound, rebind busy workers */
for_each_busy_worker(worker, i, pos, gcwq) {
struct work_struct *rebind_work = &worker->rebind_work;
+ unsigned long worker_flags = worker->flags;
- /* morph UNBOUND to REBIND */
- worker->flags &= ~WORKER_UNBOUND;
- worker->flags |= WORKER_REBIND;
+ /* morph UNBOUND to REBIND atomically */
+ worker_flags &= ~WORKER_UNBOUND;
+ worker_flags |= WORKER_REBIND;
+ ACCESS_ONCE(worker->flags) = worker_flags;
if (test_and_set_bit(WORK_STRUCT_PENDING_BIT,
work_data_bits(rebind_work)))
@@ -1449,6 +1452,34 @@ retry:
worker->scheduled.next,
work_color_to_flags(WORK_NO_COLOR));
}
+
+ /*
+ * All idle workers are rebound and waiting for %WORKER_REBIND to
+ * be cleared inside idle_worker_rebind(). Clear and release.
+ * Clearing %WORKER_REBIND from this foreign context is safe
+ * because these workers are still guaranteed to be idle.
+ *
+ * We need to make sure all idle workers passed WORKER_REBIND wait
+ * in idle_worker_rebind() before returning; otherwise, workers can
+ * get stuck at the wait if hotplug cycle repeats.
+ */
+ idle_rebind.cnt = 1;
+ INIT_COMPLETION(idle_rebind.done);
+
+ for_each_worker_pool(pool, gcwq) {
+ list_for_each_entry(worker, &pool->idle_list, entry) {
+ worker->flags &= ~WORKER_REBIND;
+ idle_rebind.cnt++;
+ }
+ }
+
+ wake_up_all(&gcwq->rebind_hold);
+
+ if (--idle_rebind.cnt) {
+ spin_unlock_irq(&gcwq->lock);
+ wait_for_completion(&idle_rebind.done);
+ spin_lock_irq(&gcwq->lock);
+ }
}
static struct worker *alloc_worker(void)
@@ -1794,9 +1825,45 @@ static bool manage_workers(struct worker *worker)
struct worker_pool *pool = worker->pool;
bool ret = false;
- if (!mutex_trylock(&pool->manager_mutex))
+ if (pool->flags & POOL_MANAGING_WORKERS)
return ret;
+ pool->flags |= POOL_MANAGING_WORKERS;
+
+ /*
+ * To simplify both worker management and CPU hotplug, hold off
+ * management while hotplug is in progress. CPU hotplug path can't
+ * grab %POOL_MANAGING_WORKERS to achieve this because that can
+ * lead to idle worker depletion (all become busy thinking someone
+ * else is managing) which in turn can result in deadlock under
+ * extreme circumstances. Use @pool->manager_mutex to synchronize
+ * manager against CPU hotplug.
+ *
+ * manager_mutex would always be free unless CPU hotplug is in
+ * progress. trylock first without dropping @gcwq->lock.
+ */
+ if (unlikely(!mutex_trylock(&pool->manager_mutex))) {
+ spin_unlock_irq(&pool->gcwq->lock);
+ mutex_lock(&pool->manager_mutex);
+ /*
+ * CPU hotplug could have happened while we were waiting
+ * for manager_mutex. Hotplug itself can't handle us
+ * because manager isn't either on idle or busy list, and
+ * @gcwq's state and ours could have deviated.
+ *
+ * As hotplug is now excluded via manager_mutex, we can
+ * simply try to bind. It will succeed or fail depending
+ * on @gcwq's current state. Try it and adjust
+ * %WORKER_UNBOUND accordingly.
+ */
+ if (worker_maybe_bind_and_lock(worker))
+ worker->flags &= ~WORKER_UNBOUND;
+ else
+ worker->flags |= WORKER_UNBOUND;
+
+ ret = true;
+ }
+
pool->flags &= ~POOL_MANAGE_WORKERS;
/*
@@ -1806,6 +1873,7 @@ static bool manage_workers(struct worker *worker)
ret |= maybe_destroy_workers(pool);
ret |= maybe_create_worker(pool);
+ pool->flags &= ~POOL_MANAGING_WORKERS;
mutex_unlock(&pool->manager_mutex);
return ret;
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-20 02:54:59 +0000