| Message ID | 20230903170736.513347-13-dmitry.osipenko@collabora.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Add generic memory shrinker to VirtIO-GPU and Panfrost DRM drivers | expand |
On Sun, 3 Sep 2023 20:07:28 +0300 Dmitry Osipenko <dmitry.osipenko@collabora.com> wrote: > Add lockless drm_gem_shmem_get_pages() helper that skips taking reservation > lock if pages_use_count is non-zero, leveraging from atomicity of the > refcount_t. Make drm_gem_shmem_mmap() to utilize the new helper. > > Suggested-by: Boris Brezillon <boris.brezillon@collabora.com> > Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com> Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com> > --- > drivers/gpu/drm/drm_gem_shmem_helper.c | 19 +++++++++++++++---- > 1 file changed, 15 insertions(+), 4 deletions(-) > > diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c > index a0faef3e762d..d93ebfef20c7 100644 > --- a/drivers/gpu/drm/drm_gem_shmem_helper.c > +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c > @@ -227,6 +227,20 @@ void drm_gem_shmem_put_pages_locked(struct drm_gem_shmem_object *shmem) > } > EXPORT_SYMBOL_GPL(drm_gem_shmem_put_pages_locked); > > +static int drm_gem_shmem_get_pages(struct drm_gem_shmem_object *shmem) > +{ > + int ret; > + > + if (refcount_inc_not_zero(&shmem->pages_use_count)) > + return 0; > + > + dma_resv_lock(shmem->base.resv, NULL); > + ret = drm_gem_shmem_get_pages_locked(shmem); > + dma_resv_unlock(shmem->base.resv); > + > + return ret; > +} > + > static int drm_gem_shmem_pin_locked(struct drm_gem_shmem_object *shmem) > { > int ret; > @@ -610,10 +624,7 @@ int drm_gem_shmem_mmap(struct drm_gem_shmem_object *shmem, struct vm_area_struct > return ret; > } > > - dma_resv_lock(shmem->base.resv, NULL); > - ret = drm_gem_shmem_get_pages_locked(shmem); > - dma_resv_unlock(shmem->base.resv); > - > + ret = drm_gem_shmem_get_pages(shmem); > if (ret) > return ret; >
diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c index a0faef3e762d..d93ebfef20c7 100644 --- a/drivers/gpu/drm/drm_gem_shmem_helper.c +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c @@ -227,6 +227,20 @@ void drm_gem_shmem_put_pages_locked(struct drm_gem_shmem_object *shmem) } EXPORT_SYMBOL_GPL(drm_gem_shmem_put_pages_locked); +static int drm_gem_shmem_get_pages(struct drm_gem_shmem_object *shmem) +{ + int ret; + + if (refcount_inc_not_zero(&shmem->pages_use_count)) + return 0; + + dma_resv_lock(shmem->base.resv, NULL); + ret = drm_gem_shmem_get_pages_locked(shmem); + dma_resv_unlock(shmem->base.resv); + + return ret; +} + static int drm_gem_shmem_pin_locked(struct drm_gem_shmem_object *shmem) { int ret; @@ -610,10 +624,7 @@ int drm_gem_shmem_mmap(struct drm_gem_shmem_object *shmem, struct vm_area_struct return ret; } - dma_resv_lock(shmem->base.resv, NULL); - ret = drm_gem_shmem_get_pages_locked(shmem); - dma_resv_unlock(shmem->base.resv); - + ret = drm_gem_shmem_get_pages(shmem); if (ret) return ret;
Add lockless drm_gem_shmem_get_pages() helper that skips taking reservation lock if pages_use_count is non-zero, leveraging from atomicity of the refcount_t. Make drm_gem_shmem_mmap() to utilize the new helper. Suggested-by: Boris Brezillon <boris.brezillon@collabora.com> Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com> --- drivers/gpu/drm/drm_gem_shmem_helper.c | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-)