lkml.org 
[lkml]   [2018]   [Jun]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Date
    Subject[PATCH 3.16 254/410] workqueue: Allow retrieval of current task's work struct
    3.16.57-rc1 review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Lukas Wunner <lukas@wunner.de>

    commit 27d4ee03078aba88c5e07dcc4917e8d01d046f38 upstream.

    Introduce a helper to retrieve the current task's work struct if it is
    a workqueue worker.

    This allows us to fix a long-standing deadlock in several DRM drivers
    wherein the ->runtime_suspend callback waits for a specific worker to
    finish and that worker in turn calls a function which waits for runtime
    suspend to finish. That function is invoked from multiple call sites
    and waiting for runtime suspend to finish is the correct thing to do
    except if it's executing in the context of the worker.

    Cc: Lai Jiangshan <jiangshanlai@gmail.com>
    Cc: Dave Airlie <airlied@redhat.com>
    Cc: Ben Skeggs <bskeggs@redhat.com>
    Cc: Alex Deucher <alexander.deucher@amd.com>
    Acked-by: Tejun Heo <tj@kernel.org>
    Reviewed-by: Lyude Paul <lyude@redhat.com>
    Signed-off-by: Lukas Wunner <lukas@wunner.de>
    Link: https://patchwork.freedesktop.org/patch/msgid/2d8f603074131eb87e588d2b803a71765bd3a2fd.1518338788.git.lukas@wunner.de
    Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
    ---
    include/linux/workqueue.h | 1 +
    kernel/workqueue.c | 16 ++++++++++++++++
    2 files changed, 17 insertions(+)

    --- a/include/linux/workqueue.h
    +++ b/include/linux/workqueue.h
    @@ -455,6 +455,7 @@ extern bool cancel_delayed_work_sync(str

    extern void workqueue_set_max_active(struct workqueue_struct *wq,
    int max_active);
    +extern struct work_struct *current_work(void);
    extern bool current_is_workqueue_rescuer(void);
    extern bool workqueue_congested(int cpu, struct workqueue_struct *wq);
    extern unsigned int work_busy(struct work_struct *work);
    --- a/kernel/workqueue.c
    +++ b/kernel/workqueue.c
    @@ -4369,6 +4369,22 @@ void workqueue_set_max_active(struct wor
    EXPORT_SYMBOL_GPL(workqueue_set_max_active);

    /**
    + * current_work - retrieve %current task's work struct
    + *
    + * Determine if %current task is a workqueue worker and what it's working on.
    + * Useful to find out the context that the %current task is running in.
    + *
    + * Return: work struct if %current task is a workqueue worker, %NULL otherwise.
    + */
    +struct work_struct *current_work(void)
    +{
    + struct worker *worker = current_wq_worker();
    +
    + return worker ? worker->current_work : NULL;
    +}
    +EXPORT_SYMBOL(current_work);
    +
    +/**
    * current_is_workqueue_rescuer - is %current workqueue rescuer?
    *
    * Determine whether %current is a workqueue rescuer. Can be used from
    \
     
     \ /
      Last update: 2018-06-07 17:16    [W:5.530 / U:0.568 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site