On 07/30/2013 08:40 PM, Tejun Heo wrote:
> dbf2576e37 ("workqueue: make all workqueues non-reentrant") made
> WQ_NON_REENTRANT no-op but the following patches didn't remove the
> flag or update the documentation. Let's mark the flag deprecated and
> update the documentation accordingly.
>
> Signed-off-by: Tejun Heo <t...@kernel.org>
Acked-by: Lai Jiangshan <la...@cn.fujitsu.com>
> ---
> Documentation/workqueue.txt | 18 ++++++------------
> include/linux/workqueue.h | 7 ++++++-
> 2 files changed, 12 insertions(+), 13 deletions(-)
>
> diff --git a/Documentation/workqueue.txt b/Documentation/workqueue.txt
> index a6ab4b6..67113f6 100644
> --- a/Documentation/workqueue.txt
> +++ b/Documentation/workqueue.txt
> @@ -100,8 +100,8 @@ Subsystems and drivers can create and queue work items
> through special
> workqueue API functions as they see fit. They can influence some
> aspects of the way the work items are executed by setting flags on the
> workqueue they are putting the work item on. These flags include
> -things like CPU locality, reentrancy, concurrency limits, priority and
> -more. To get a detailed overview refer to the API description of
> +things like CPU locality, concurrency limits, priority and more. To
> +get a detailed overview refer to the API description of
> alloc_workqueue() below.
>
> When a work item is queued to a workqueue, the target gcwq and
> @@ -166,16 +166,6 @@ resources, scheduled and executed.
>
> @flags:
>
> - WQ_NON_REENTRANT
> -
> - By default, a wq guarantees non-reentrance only on the same
> - CPU. A work item may not be executed concurrently on the same
> - CPU by multiple workers but is allowed to be executed
> - concurrently on multiple CPUs. This flag makes sure
> - non-reentrance is enforced across all CPUs. Work items queued
> - to a non-reentrant wq are guaranteed to be executed by at most
> - one worker system-wide at any given time.
> -
> WQ_UNBOUND
>
> Work items queued to an unbound wq are served by a special
> @@ -233,6 +223,10 @@ resources, scheduled and executed.
>
> This flag is meaningless for unbound wq.
>
> +Note that the flag WQ_NON_REENTRANT no longer exists as all workqueues
> +are now non-reentrant - any work item is guaranteed to be executed by
> +at most one worker system-wide at any given time.
> +
> @max_active:
>
> @max_active determines the maximum number of execution contexts per
> diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
> index a0ed78a..594521b 100644
> --- a/include/linux/workqueue.h
> +++ b/include/linux/workqueue.h
> @@ -295,7 +295,12 @@ static inline unsigned int work_static(struct
> work_struct *work) { return 0; }
> * Documentation/workqueue.txt.
> */
> enum {
> - WQ_NON_REENTRANT = 1 << 0, /* guarantee non-reentrance */
> + /*
> + * All wqs are now non-reentrant making the following flag
> + * meaningless. Will be removed.
> + */
> + WQ_NON_REENTRANT = 1 << 0, /* DEPRECATED */
> +
> WQ_UNBOUND = 1 << 1, /* not bound to any cpu */
> WQ_FREEZABLE = 1 << 2, /* freeze during suspend */
> WQ_MEM_RECLAIM = 1 << 3, /* may be used for memory reclaim */
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