Messages in this thread Patch in this message | | | From | Frederic Weisbecker <> | Subject | [PATCH 2/3] workqueues: Account unbound workqueue in a seperate list | Date | Fri, 14 Mar 2014 17:38:50 +0100 |
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The workqueues are all listed in a global list protected by a big mutex. And this big mutex is used in apply_workqueue_attrs() as well.
Now as we plan to implement a directory to control the cpumask of all non-ABI unbound workqueues, we want to be able to iterate over all unbound workqueues and call apply_workqueue_attrs() for each of them with the new cpumask.
But the risk for a deadlock is on the way: we need to iterate the list of workqueues under wq_pool_mutex. But then apply_workqueue_attrs() itself calls wq_pool_mutex.
The easiest solution to work around this is to keep track of unbound workqueues in a separate list with a separate mutex.
It's not very pretty unfortunately.
Cc: Christoph Lameter <cl@linux.com> Cc: Kevin Hilman <khilman@linaro.org> Cc: Mike Galbraith <bitbucket@online.de> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Tejun Heo <tj@kernel.org> Cc: Viresh Kumar <viresh.kumar@linaro.org> Not-Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> --- kernel/workqueue.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+)
diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 4d230e3..ad8f727 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -232,6 +232,7 @@ struct wq_device; struct workqueue_struct { struct list_head pwqs; /* WR: all pwqs of this wq */ struct list_head list; /* PL: list of all workqueues */ + struct list_head unbound_list; /* PL: list of unbound workqueues */ struct mutex mutex; /* protects this wq */ int work_color; /* WQ: current work color */ @@ -288,9 +289,11 @@ static bool wq_numa_enabled; /* unbound NUMA affinity enabled */ static struct workqueue_attrs *wq_update_unbound_numa_attrs_buf; static DEFINE_MUTEX(wq_pool_mutex); /* protects pools and workqueues list */ +static DEFINE_MUTEX(wq_unbound_mutex); /* protects list of unbound workqueues */ static DEFINE_SPINLOCK(wq_mayday_lock); /* protects wq->maydays list */ static LIST_HEAD(workqueues); /* PL: list of all workqueues */ +static LIST_HEAD(workqueues_unbound); /* PL: list of unbound workqueues */ static bool workqueue_freezing; /* PL: have wqs started freezing? */ /* the per-cpu worker pools */ @@ -4263,6 +4266,12 @@ struct workqueue_struct *__alloc_workqueue_key(const char *fmt, mutex_unlock(&wq_pool_mutex); + if (wq->flags & WQ_UNBOUND) { + mutex_lock(&wq_unbound_mutex); + list_add(&wq->unbound_list, &workqueues_unbound); + mutex_unlock(&wq_unbound_mutex); + } + return wq; err_free_wq: @@ -4318,6 +4327,12 @@ void destroy_workqueue(struct workqueue_struct *wq) list_del_init(&wq->list); mutex_unlock(&wq_pool_mutex); + if (wq->flags & WQ_UNBOUND) { + mutex_lock(&wq_unbound_mutex); + list_del(&wq->unbound_list); + mutex_unlock(&wq_unbound_mutex); + } + workqueue_sysfs_unregister(wq); if (wq->rescuer) { -- 1.8.3.1
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