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Subject[PATCH 1/2 V7 for-3.6-fixes] workqueue: add POOL_MANAGING_WORKERS
Date
When hotplug happens, the plug code will also grab the manager_mutex,
it will break too_many_workers()'s assumption, and make too_many_workers()
ugly(kick the timer wrongly, no found bug).

To avoid assumption-coruption, we add the original POOL_MANAGING_WORKERS back.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
---
kernel/workqueue.c | 5 ++++-
1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index dc7b845..383548e 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;

@@ -1827,6 +1828,7 @@ static bool manage_workers(struct worker *worker)
if (!mutex_trylock(&pool->manager_mutex))
return ret;

+ pool->flags |= POOL_MANAGING_WORKERS;
pool->flags &= ~POOL_MANAGE_WORKERS;

/*
@@ -1836,6 +1838,7 @@ 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;
}
--
1.7.4.4


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