This is a note to let you know that I've just added the patch titled
drm/shmem-helper: Fix locking for drm_gem_shmem_get_pages_sgt()
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-shmem-helper-fix-locking-for-drm_gem_shmem_get_p.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 22159990d81b613c9b4cf1b6be388d04f8aa981b
Author: Asahi Lina <lina@xxxxxxxxxxxxx>
Date: Sun Feb 5 21:51:24 2023 +0900
drm/shmem-helper: Fix locking for drm_gem_shmem_get_pages_sgt()
[ Upstream commit ddddedaa0db99481c5e5abe628ad54f65e8765bc ]
Other functions touching shmem->sgt take the pages lock, so do that here
too. drm_gem_shmem_get_pages() & co take the same lock, so move to the
_locked() variants to avoid recursive locking.
Discovered while auditing locking to write the Rust abstractions.
Fixes: 2194a63a818d ("drm: Add library for shmem backed GEM objects")
Fixes: 4fa3d66f132b ("drm/shmem: Do dma_unmap_sg before purging pages")
Signed-off-by: Asahi Lina <lina@xxxxxxxxxxxxx>
Reviewed-by: Javier Martinez Canillas <javierm@xxxxxxxxxx>
Signed-off-by: Javier Martinez Canillas <javierm@xxxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20230205125124.2260-1-lina@xxxxxxxxxxxxx
(cherry picked from commit aa8c85affe3facd3842c8912186623415931cc72)
Signed-off-by: Javier Martinez Canillas <javierm@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
index b602cd72a1205..2c559b310cad3 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -681,23 +681,7 @@ struct sg_table *drm_gem_shmem_get_sg_table(struct drm_gem_shmem_object *shmem)
}
EXPORT_SYMBOL_GPL(drm_gem_shmem_get_sg_table);
-/**
- * drm_gem_shmem_get_pages_sgt - Pin pages, dma map them, and return a
- * scatter/gather table for a shmem GEM object.
- * @shmem: shmem GEM object
- *
- * This function returns a scatter/gather table suitable for driver usage. If
- * the sg table doesn't exist, the pages are pinned, dma-mapped, and a sg
- * table created.
- *
- * This is the main function for drivers to get at backing storage, and it hides
- * and difference between dma-buf imported and natively allocated objects.
- * drm_gem_shmem_get_sg_table() should not be directly called by drivers.
- *
- * Returns:
- * A pointer to the scatter/gather table of pinned pages or errno on failure.
- */
-struct sg_table *drm_gem_shmem_get_pages_sgt(struct drm_gem_shmem_object *shmem)
+static 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;
@@ -708,7 +692,7 @@ struct sg_table *drm_gem_shmem_get_pages_sgt(struct drm_gem_shmem_object *shmem)
WARN_ON(obj->import_attach);
- ret = drm_gem_shmem_get_pages(shmem);
+ ret = drm_gem_shmem_get_pages_locked(shmem);
if (ret)
return ERR_PTR(ret);
@@ -730,10 +714,40 @@ struct sg_table *drm_gem_shmem_get_pages_sgt(struct drm_gem_shmem_object *shmem)
sg_free_table(sgt);
kfree(sgt);
err_put_pages:
- drm_gem_shmem_put_pages(shmem);
+ drm_gem_shmem_put_pages_locked(shmem);
return ERR_PTR(ret);
}
-EXPORT_SYMBOL_GPL(drm_gem_shmem_get_pages_sgt);
+
+/**
+ * drm_gem_shmem_get_pages_sgt - Pin pages, dma map them, and return a
+ * scatter/gather table for a shmem GEM object.
+ * @shmem: shmem GEM object
+ *
+ * This function returns a scatter/gather table suitable for driver usage. If
+ * the sg table doesn't exist, the pages are pinned, dma-mapped, and a sg
+ * table created.
+ *
+ * This is the main function for drivers to get at backing storage, and it hides
+ * and difference between dma-buf imported and natively allocated objects.
+ * drm_gem_shmem_get_sg_table() should not be directly called by drivers.
+ *
+ * Returns:
+ * A pointer to the scatter/gather table of pinned pages or errno on failure.
+ */
+struct sg_table *drm_gem_shmem_get_pages_sgt(struct drm_gem_shmem_object *shmem)
+{
+ int ret;
+ struct sg_table *sgt;
+
+ ret = mutex_lock_interruptible(&shmem->pages_lock);
+ if (ret)
+ return ERR_PTR(ret);
+ sgt = drm_gem_shmem_get_pages_sgt_locked(shmem);
+ mutex_unlock(&shmem->pages_lock);
+
+ return sgt;
+}
+EXPORT_SYMBOL(drm_gem_shmem_get_pages_sgt);
/**
* drm_gem_shmem_prime_import_sg_table - Produce a shmem GEM object from
