Received-SPF: pass (google.com: domain of linux-kernel+bounces-18248-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.199.223 as permitted sender) client-ip=147.75.199.223;
From: Dmitry Osipenko <dmitry.osipenko@collabora.com>
To: David Airlie <airlied@gmail.com>,
	Gerd Hoffmann <kraxel@redhat.com>,
	Gurchetan Singh <gurchetansingh@chromium.org>,
	Chia-I Wu <olvaffe@gmail.com>,
	Daniel Vetter <daniel@ffwll.ch>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Maxime Ripard <mripard@kernel.org>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	=?UTF-8?q?Christian=20K=C3=B6nig?= <christian.koenig@amd.com>,
	Qiang Yu <yuq825@gmail.com>,
	Steven Price <steven.price@arm.com>,
	Boris Brezillon <boris.brezillon@collabora.com>,
	Emma Anholt <emma@anholt.net>,
	Melissa Wen <mwen@igalia.com>
Cc: dri-devel@lists.freedesktop.org,
	linux-kernel@vger.kernel.org,
	kernel@collabora.com,
	virtualization@lists.linux-foundation.org
Subject: [PATCH v19 10/30] drm/shmem-helper: Switch drm_gem_shmem_vmap/vunmap to use pin/unpin
Date: Fri,  5 Jan 2024 21:46:04 +0300
Message-ID: <20240105184624.508603-11-dmitry.osipenko@collabora.com>
In-Reply-To: <20240105184624.508603-1-dmitry.osipenko@collabora.com>
References: <20240105184624.508603-1-dmitry.osipenko@collabora.com>
Precedence: bulk
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit

The vmapped pages shall be pinned in memory and previously get/put_pages()
were implicitly hard-pinning/unpinning the pages. This will no longer be
the case with addition of memory shrinker because pages_use_count > 0 won't
determine anymore whether pages are hard-pinned (they will be soft-pinned),
while the new pages_pin_count will do the hard-pinning. Switch the
vmap/vunmap() to use pin/unpin() functions in a preparation of addition
of the memory shrinker support to drm-shmem.

Acked-by: Maxime Ripard <mripard@kernel.org>
Reviewed-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 ++++++++++++-------
 include/drm/drm_gem_shmem_helper.h     |  2 +-
 2 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
index 1c032513abf1..9c89183f81b7 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -256,6 +256,14 @@ static int drm_gem_shmem_pin_locked(struct drm_gem_shmem_object *shmem)
 	return ret;
 }
 
+static void drm_gem_shmem_unpin_locked(struct drm_gem_shmem_object *shmem)
+{
+	dma_resv_assert_held(shmem->base.resv);
+
+	if (refcount_dec_and_test(&shmem->pages_pin_count))
+		drm_gem_shmem_put_pages_locked(shmem);
+}
+
 /**
  * drm_gem_shmem_pin - Pin backing pages for a shmem GEM object
  * @shmem: shmem GEM object
@@ -303,10 +311,7 @@ void drm_gem_shmem_unpin(struct drm_gem_shmem_object *shmem)
 		return;
 
 	dma_resv_lock(shmem->base.resv, NULL);
-
-	if (refcount_dec_and_test(&shmem->pages_pin_count))
-		drm_gem_shmem_put_pages_locked(shmem);
-
+	drm_gem_shmem_unpin_locked(shmem);
 	dma_resv_unlock(shmem->base.resv);
 }
 EXPORT_SYMBOL_GPL(drm_gem_shmem_unpin);
@@ -344,7 +349,7 @@ int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem,
 			return 0;
 		}
 
-		ret = drm_gem_shmem_get_pages_locked(shmem);
+		ret = drm_gem_shmem_pin_locked(shmem);
 		if (ret)
 			goto err_zero_use;
 
@@ -367,7 +372,7 @@ int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem,
 
 err_put_pages:
 	if (!obj->import_attach)
-		drm_gem_shmem_put_pages_locked(shmem);
+		drm_gem_shmem_unpin_locked(shmem);
 err_zero_use:
 	shmem->vmap_use_count = 0;
 
@@ -404,7 +409,7 @@ void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem,
 			return;
 
 		vunmap(shmem->vaddr);
-		drm_gem_shmem_put_pages_locked(shmem);
+		drm_gem_shmem_unpin_locked(shmem);
 	}
 
 	shmem->vaddr = NULL;
diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h
index 2c5dc62df20c..80623b897803 100644
--- a/include/drm/drm_gem_shmem_helper.h
+++ b/include/drm/drm_gem_shmem_helper.h
@@ -124,7 +124,7 @@ int drm_gem_shmem_madvise_locked(struct drm_gem_shmem_object *shmem, int madv);
 static inline bool drm_gem_shmem_is_purgeable(struct drm_gem_shmem_object *shmem)
 {
 	return (shmem->madv > 0) &&
-		!shmem->vmap_use_count && shmem->sgt &&
+		!refcount_read(&shmem->pages_pin_count) && shmem->sgt &&
 		!shmem->base.dma_buf && !shmem->base.import_attach;
 }
 
-- 
2.43.0