Messages in this thread Patch in this message | | | From | Dmitry Osipenko <> | Subject | [PATCH v18 08/26] drm/shmem-helper: Add and use lockless drm_gem_shmem_get_pages() | Date | Mon, 30 Oct 2023 02:01:47 +0300 |
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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.
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com> 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(-)
diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c index 6e02643ed87e..41b749bedb11 100644 --- a/drivers/gpu/drm/drm_gem_shmem_helper.c +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c @@ -226,6 +226,20 @@ 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; @@ -609,10 +623,7 @@ 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; -- 2.41.0
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