On Fri, 19 May 2023 at 09:55, Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx> wrote: > > drmm_mutex_init() needs to be defined as a macro if we want > lockdep to classify locks properly. If we don't do that, all locks > will be considered as belonging to the same lock class, leading to > false positive deadlock reports. > > Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx> > Reported-by: Sarah Walker <sarah.walker@xxxxxxxxxx> Yeah, we also encountered the same issue. Patch is here: https://patchwork.freedesktop.org/patch/537605/?series=117891&rev=2 > --- > drivers/gpu/drm/drm_managed.c | 26 -------------------------- > include/drm/drm_managed.h | 30 +++++++++++++++++++++++++++++- > 2 files changed, 29 insertions(+), 27 deletions(-) > > diff --git a/drivers/gpu/drm/drm_managed.c b/drivers/gpu/drm/drm_managed.c > index 4cf214de50c4..71c49819a7a2 100644 > --- a/drivers/gpu/drm/drm_managed.c > +++ b/drivers/gpu/drm/drm_managed.c > @@ -263,29 +263,3 @@ void drmm_kfree(struct drm_device *dev, void *data) > free_dr(dr_match); > } > EXPORT_SYMBOL(drmm_kfree); > - > -static void drmm_mutex_release(struct drm_device *dev, void *res) > -{ > - struct mutex *lock = res; > - > - mutex_destroy(lock); > -} > - > -/** > - * drmm_mutex_init - &drm_device-managed mutex_init() > - * @dev: DRM device > - * @lock: lock to be initialized > - * > - * Returns: > - * 0 on success, or a negative errno code otherwise. > - * > - * This is a &drm_device-managed version of mutex_init(). The initialized > - * lock is automatically destroyed on the final drm_dev_put(). > - */ > -int drmm_mutex_init(struct drm_device *dev, struct mutex *lock) > -{ > - mutex_init(lock); > - > - return drmm_add_action_or_reset(dev, drmm_mutex_release, lock); > -} > -EXPORT_SYMBOL(drmm_mutex_init); > diff --git a/include/drm/drm_managed.h b/include/drm/drm_managed.h > index 359883942612..87ffb92a16ba 100644 > --- a/include/drm/drm_managed.h > +++ b/include/drm/drm_managed.h > @@ -105,6 +105,34 @@ char *drmm_kstrdup(struct drm_device *dev, const char *s, gfp_t gfp); > > void drmm_kfree(struct drm_device *dev, void *data); > > -int drmm_mutex_init(struct drm_device *dev, struct mutex *lock); > +/* Private function, don't use. */ > +static inline void __drmm_mutex_release(struct drm_device *dev, void *res) > +{ > + struct mutex *lock = res; > + > + mutex_destroy(lock); > +} > + > +/** > + * drmm_mutex_init - &drm_device-managed mutex_init() > + * @dev: DRM device > + * @lock: lock to be initialized > + * > + * Returns: > + * 0 on success, or a negative errno code otherwise. > + * > + * This is a &drm_device-managed version of mutex_init(). The initialized > + * lock is automatically destroyed on the final drm_dev_put(). > + * > + * This needs to be defined as a macro to let lockdep classify locks > + * properly. If we don't do that, all locks will be considered as > + * belonging to the same lock class, leading to false positive lockdep > + * reports. > + */ > +#define drmm_mutex_init(dev, lock) \ > + ({\ > + mutex_init(lock); \ > + drmm_add_action_or_reset(dev, __drmm_mutex_release, lock); \ > + }) > > #endif > -- > 2.40.1 >
