[PATCH] drm/radeon: Handle workqueue allocation failure

[Will Deacon <will@kernel.org>]

In the highly unlikely event that we fail to allocate the "radeon-crtc"
workqueue, we should bail cleanly rather than blindly march on with a
NULL pointer installed for the 'flip_queue' field of the 'radeon_crtc'
structure.

This was reported previously by Nicolas, but I don't think his fix was
correct:

Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: "David (ChunMing) Zhou" <David1.Zhou@amd.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Reported-by: Nicolas Waisman <nico@semmle.com>
Link: https://lore.kernel.org/lkml/CADJ_3a8WFrs5NouXNqS5WYe7rebFP+_A5CheeqAyD_p7DFJJcg@mail.gmail.com/
Signed-off-by: Will Deacon <will@kernel.org>
---

Compile-tested only.

 drivers/gpu/drm/radeon/radeon_display.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/radeon/radeon_display.c b/drivers/gpu/drm/radeon/radeon_display.c
index e81b01f8db90..3e4ef1380fca 100644
--- a/drivers/gpu/drm/radeon/radeon_display.c
+++ b/drivers/gpu/drm/radeon/radeon_display.c
@@ -672,17 +672,25 @@ static void radeon_crtc_init(struct drm_device *dev, int index)
 {
 	struct radeon_device *rdev = dev->dev_private;
 	struct radeon_crtc *radeon_crtc;
+	struct workqueue_struct *wq;
 	int i;
 
 	radeon_crtc = kzalloc(sizeof(struct radeon_crtc) + (RADEONFB_CONN_LIMIT * sizeof(struct drm_connector *)), GFP_KERNEL);
 	if (radeon_crtc == NULL)
 		return;
 
+	wq = alloc_workqueue("radeon-crtc", WQ_HIGHPRI, 0);
+	if (unlikely(!wq)) {
+		kfree(radeon_crtc);
+		return;
+	}
+
 	drm_crtc_init(dev, &radeon_crtc->base, &radeon_crtc_funcs);
 
 	drm_mode_crtc_set_gamma_size(&radeon_crtc->base, 256);
 	radeon_crtc->crtc_id = index;
-	radeon_crtc->flip_queue = alloc_workqueue("radeon-crtc", WQ_HIGHPRI, 0);
+	radeon_crtc->flip_queue = wq;
+
 	rdev->mode_info.crtcs[index] = radeon_crtc;
 
 	if (rdev->family >= CHIP_BONAIRE) {
-- 
2.24.0.rc0.303.g954a862665-goog