On Tue, Apr 02, 2019 at 07:29:31AM -0700, Paul E. McKenney wrote:
> Having DEFINE_SRCU() or DEFINE_STATIC_SRCU() in a loadable module
> requires that the size of the reserved region be increased, which is not
> something we really want to be doing. This commit therefore removes
> the DEFINE_STATIC_SRCU() from drivers/gpu/drm/drm_drv.c in favor of
> defining drm_unplug_srcu as a simple srcu_struct, initializing it in
> drm_core_init(), and cleaning it up in drm_core_exit().
>
> In this particular case, drm_unplug_srcu is statically allocated and thus
> guaranteed to be initially zero. Unfortunately, cleanup_srcu_struct()
> cannot rely on this in the general case (which includes dynamically
> allocated srcu_struct structures), and therefore cannot tell whether it
> is being called on something that has been passed to init_srcu_struct().
> Thus the code added to drm_core_init() is a bit non-standard.
>
> Reported-by: kbuild test robot <l...@intel.com>
> Signed-off-by: Paul E. McKenney <paul...@linux.ibm.com>
> Cc: Maarten Lankhorst <maarten.lankho...@linux.intel.com>
> Cc: Maxime Ripard <maxime.rip...@bootlin.com>
> Cc: Sean Paul <s...@poorly.run>
> Cc: David Airlie <airl...@linux.ie>
> Cc: Daniel Vetter <dan...@ffwll.ch>
> Cc: Tejun Heo <t...@kernel.org>
> Cc: <dri-devel@lists.freedesktop.org>
Seems reasonable (but I don't have the full patch series as context).
Reviewed-by: Daniel Vetter <daniel.vet...@ffwll.ch>
Any preferences as to how this should be merged? Upfront ack for merging
through rcu trees if that helps you.
-Daniel
> ---
> drivers/gpu/drm/drm_drv.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
> index 381581b01d48..ce4582af814d 100644
> --- a/drivers/gpu/drm/drm_drv.c
> +++ b/drivers/gpu/drm/drm_drv.c
> @@ -77,7 +77,7 @@ static bool drm_core_init_complete = false;
>
> static struct dentry *drm_debugfs_root;
>
> -DEFINE_STATIC_SRCU(drm_unplug_srcu);
> +static struct srcu_struct drm_unplug_srcu;
>
> /*
> * DRM Minors
> @@ -958,12 +958,18 @@ static void drm_core_exit(void)
> drm_sysfs_destroy();
> idr_destroy(&drm_minors_idr);
> drm_connector_ida_destroy();
> + cleanup_srcu_struct(&drm_unplug_srcu);
> }
>
> static int __init drm_core_init(void)
> {
> int ret;
>
> + ret = init_srcu_struct(&drm_unplug_srcu);
> + if (ret) {
> + DRM_ERROR("Cannot create DRM class: %d\n", ret);
> + return ret; /* cannot cleanup after failed srcu_struct init. */
> + }
> drm_connector_ida_init();
> idr_init(&drm_minors_idr);
>
> --
> 2.17.1
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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