linux-kernel - [PATCH 5.10 096/290] drm/shmem-helpers: vunmap: Dont put pages for dma-buf

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Date:   Mon, 15 Mar 2021 14:53:09 +0100
From:   gregkh@...uxfoundation.org
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Noralf Trønnes <noralf@...nnes.org>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>
Subject: [PATCH 5.10 096/290] drm/shmem-helpers: vunmap: Dont put pages for dma-buf

From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

From: Noralf Trønnes <noralf@...nnes.org>

commit 64e194e278673bceb68fb2dde7dbc3d812bfceb3 upstream.

dma-buf importing was reworked in commit 7d2cd72a9aa3
("drm/shmem-helpers: Simplify dma-buf importing"). Before that commit
drm_gem_shmem_prime_import_sg_table() did set ->pages_use_count=1 and
drm_gem_shmem_vunmap_locked() could call drm_gem_shmem_put_pages()
unconditionally. Now without the use count set, put pages is called also
on dma-bufs. Fix this by only putting pages if it's not imported.

Signed-off-by: Noralf Trønnes <noralf@...nnes.org>
Fixes: 7d2cd72a9aa3 ("drm/shmem-helpers: Simplify dma-buf importing")
Cc: Daniel Vetter <daniel.vetter@...ll.ch>
Cc: Thomas Zimmermann <tzimmermann@...e.de>
Acked-by: Thomas Zimmermann <tzimmermann@...e.de>
Tested-by: Thomas Zimmermann <tzimmermann@...e.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20210219122203.51130-1-noralf@tronnes.org
(cherry picked from commit cdea72518a2b38207146e92e1c9e2fac15975679)
Signed-off-by: Thomas Zimmermann <tzimmermann@...e.de>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/gpu/drm/drm_gem_shmem_helper.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -340,13 +340,14 @@ static void drm_gem_shmem_vunmap_locked(
 	if (--shmem->vmap_use_count > 0)
 		return;
 
-	if (obj->import_attach)
+	if (obj->import_attach) {
 		dma_buf_vunmap(obj->import_attach->dmabuf, shmem->vaddr);
-	else
+	} else {
 		vunmap(shmem->vaddr);
+		drm_gem_shmem_put_pages(shmem);
+	}
 
 	shmem->vaddr = NULL;
-	drm_gem_shmem_put_pages(shmem);
 }
 
 /*