Re: [PATCH] workqueue: fix pool ID allocation leakage and remove BUILD_BUG_ON() in init_workqueues

[Tejun Heo <tj@kernel.org>]

On Tue, Sep 10, 2013 at 09:52:35AM +0800, Libin wrote:
> From: Li Bin <huawei.libin@huawei.com>
> 
> When one work starts execution, the high bits of work's data contain
> pool ID. It can represent a maximum of WORK_OFFQ_POOL_NONE. Pool ID
> is assigned WORK_OFFQ_POOL_NONE when the work being initialized
> indicating that no pool is associated and get_work_pool() uses it to
> check the associated pool. So if worker_pool_assign_id() assigns a
> ID greater than or equal WORK_OFFQ_POOL_NONE to a pool, it triggers
> leakage, and it may break the non-reentrance guarantee.
> 
> This patch fix this issue by modifying the worker_pool_assign_id()
> function calling idr_alloc() by setting @end param WORK_OFFQ_POOL_NONE.
> 
> Furthermore, in the current implementation, the BUILD_BUG_ON() in
> init_workqueues makes no sense. The number of worker pools needed
> cannot be determined at compile time, because the number of backing
> pools for UNBOUND workqueues is dynamic based on the assigned custom
> attributes. So remove it.
> 
> Signed-off-by: Li Bin <huawei.libin@huawei.com>

Applied to wq/for-3.12-fixes w/ minor updates.

Thanks.

-- 
tejun