[PATCH] drm/i915: Add missing check and destroy for alloc_workqueue

[Jiasheng Jiang]

Add checks for the return value of alloc_workqueue and
alloc_ordered_workqueue as they may return NULL pointer and cause NULL
pointer dereference.
Moreover, destroy them when fails later in order to avoid memory leak.
Because in `drivers/gpu/drm/i915/i915_driver.c`, if
intel_modeset_init_noirq fails, its workqueues will not be destroyed.

Fixes: c26a058680dc ("drm/i915: Use a high priority wq for nonblocking plane 
updates")
Fixes: 757fffcfdffb ("drm/i915: Put all non-blocking modesets onto an ordered 
wq")
Signed-off-by: Jiasheng Jiang <jiash...@iscas.ac.cn>
---
 drivers/gpu/drm/i915/display/intel_display.c | 21 ++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_display.c 
b/drivers/gpu/drm/i915/display/intel_display.c
index 6c2686ecb62a..58f6840d6bd8 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -8655,26 +8655,35 @@ int intel_modeset_init_noirq(struct drm_i915_private 
*i915)
        intel_dmc_ucode_init(i915);
 
        i915->display.wq.modeset = alloc_ordered_workqueue("i915_modeset", 0);
+       if (!i915->display.wq.modeset) {
+               ret = -ENOMEM;
+               goto cleanup_vga_client_pw_domain_dmc;
+       }
+
        i915->display.wq.flip = alloc_workqueue("i915_flip", WQ_HIGHPRI |
                                                WQ_UNBOUND, 
WQ_UNBOUND_MAX_ACTIVE);
+       if (!i915->display.wq.flip) {
+               ret = -ENOMEM;
+               goto cleanup_modeset;
+       }
 
        intel_mode_config_init(i915);
 
        ret = intel_cdclk_init(i915);
        if (ret)
-               goto cleanup_vga_client_pw_domain_dmc;
+               goto cleanup_flip;
 
        ret = intel_color_init(i915);
        if (ret)
-               goto cleanup_vga_client_pw_domain_dmc;
+               goto cleanup_flip;
 
        ret = intel_dbuf_init(i915);
        if (ret)
-               goto cleanup_vga_client_pw_domain_dmc;
+               goto cleanup_flip;
 
        ret = intel_bw_init(i915);
        if (ret)
-               goto cleanup_vga_client_pw_domain_dmc;
+               goto cleanup_flip;
 
        init_llist_head(&i915->display.atomic_helper.free_list);
        INIT_WORK(&i915->display.atomic_helper.free_work,
@@ -8686,6 +8695,10 @@ int intel_modeset_init_noirq(struct drm_i915_private 
*i915)
 
        return 0;
 
+cleanup_flip:
+       destroy_workqueue(i915->display.wq.flip);
+cleanup_modeset:
+       destroy_workqueue(i915->display.wq.modeset);
 cleanup_vga_client_pw_domain_dmc:
        intel_dmc_ucode_fini(i915);
        intel_power_domains_driver_remove(i915);
-- 
2.25.1