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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 v18 20/26] drm/shmem-helper: Export drm_gem_shmem_get_pages_sgt_locked()
Date:   Mon, 30 Oct 2023 02:01:59 +0300
Message-ID: <20231029230205.93277-21-dmitry.osipenko@collabora.com>
In-Reply-To: <20231029230205.93277-1-dmitry.osipenko@collabora.com>
References: <20231029230205.93277-1-dmitry.osipenko@collabora.com>
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Export drm_gem_shmem_get_pages_sgt_locked() that will be used by virtio-gpu
shrinker during GEM swap-in operation done under the held reservation lock.

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 | 22 +++++++++++++++++++++-
 include/drm/drm_gem_shmem_helper.h     |  1 +
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
index 007521bea302..560ce565f376 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -872,12 +872,31 @@ struct sg_table *drm_gem_shmem_get_sg_table(struct drm_gem_shmem_object *shmem)
 }
 EXPORT_SYMBOL_GPL(drm_gem_shmem_get_sg_table);
 
-static struct sg_table *drm_gem_shmem_get_pages_sgt_locked(struct drm_gem_shmem_object *shmem)
+/**
+ * drm_gem_shmem_get_pages_sgt_locked - Provide a scatter/gather table of pinned
+ *                                      pages for a shmem GEM object
+ * @shmem: shmem GEM object
+ *
+ * This is a locked version of @drm_gem_shmem_get_sg_table that exports a
+ * scatter/gather table suitable for PRIME usage by calling the standard
+ * DMA mapping API.
+ *
+ * Drivers must hold GEM's reservation lock when using this function.
+ *
+ * Drivers who need to acquire an scatter/gather table for objects need to call
+ * drm_gem_shmem_get_pages_sgt() instead.
+ *
+ * Returns:
+ * A pointer to the scatter/gather table of pinned pages or error pointer on failure.
+ */
+struct sg_table *drm_gem_shmem_get_pages_sgt_locked(struct drm_gem_shmem_object *shmem)
 {
 	struct drm_gem_object *obj = &shmem->base;
 	int ret;
 	struct sg_table *sgt;
 
+	dma_resv_assert_held(shmem->base.resv);
+
 	if (shmem->sgt)
 		return shmem->sgt;
 
@@ -901,6 +920,7 @@ static struct sg_table *drm_gem_shmem_get_pages_sgt_locked(struct drm_gem_shmem_
 	kfree(sgt);
 	return ERR_PTR(ret);
 }
+EXPORT_SYMBOL_GPL(drm_gem_shmem_get_pages_sgt_locked);
 
 /**
  * drm_gem_shmem_get_pages_sgt - Pin pages, dma map them, and return a
diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h
index 3bb70616d095..6ac77c2082ed 100644
--- a/include/drm/drm_gem_shmem_helper.h
+++ b/include/drm/drm_gem_shmem_helper.h
@@ -149,6 +149,7 @@ void drm_gem_shmem_purge_locked(struct drm_gem_shmem_object *shmem);
 
 struct sg_table *drm_gem_shmem_get_sg_table(struct drm_gem_shmem_object *shmem);
 struct sg_table *drm_gem_shmem_get_pages_sgt(struct drm_gem_shmem_object *shmem);
+struct sg_table *drm_gem_shmem_get_pages_sgt_locked(struct drm_gem_shmem_object *shmem);
 
 void drm_gem_shmem_print_info(const struct drm_gem_shmem_object *shmem,
 			      struct drm_printer *p, unsigned int indent);
-- 
2.41.0