linux-kernel - [PATCH] drm/nouveau: Removes unnecessary args check in nouveau_uvmm_sm

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Message-ID: <GV1PR10MB65637F4BAABFE2D8E261E1DCE8B0A@GV1PR10MB6563.EURPRD10.PROD.OUTLOOK.COM>
Date:   Fri, 17 Nov 2023 02:22:00 +0530
From:   Yuran Pereira <yuran.pereira@...mail.com>
To:     nouveau@...ts.freedesktop.org
Cc:     Yuran Pereira <yuran.pereira@...mail.com>, kherbst@...hat.com,
        lyude@...hat.com, dakr@...hat.com, airlied@...il.com,
        daniel@...ll.ch, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org,
        linux-kernel-mentees@...ts.linuxfoundation.org
Subject: [PATCH] drm/nouveau: Removes unnecessary args check in nouveau_uvmm_sm_prepare

Checking `args` after calling `op_map_prepare` is unnecessary since
if `op_map_prepare` was to be called with  NULL args, it would lead
to a NULL pointer dereference, thus never hitting that check.

Hence this check can be removed, and a note added to remind users of
this function to ensure that args != NULL when calling this function
for a map operation as it was suggested  by Danilo [1]

[1] https://lore.kernel.org/lkml/6a1ebcef-bade-45a0-9bd9-c05f0226eb88@redhat.com

Suggested-by: Danilo Krummrich <dakr@...hat.com>
Signed-off-by: Yuran Pereira <yuran.pereira@...mail.com>
---
 drivers/gpu/drm/nouveau/nouveau_uvmm.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_uvmm.c b/drivers/gpu/drm/nouveau/nouveau_uvmm.c
index 5cf892c50f43..c8c3f1b1b604 100644
--- a/drivers/gpu/drm/nouveau/nouveau_uvmm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_uvmm.c
@@ -604,6 +604,10 @@ op_unmap_prepare(struct drm_gpuva_op_unmap *u)
 	drm_gpuva_unmap(u);
 }
 
+/*
+ * Note: @args should not be NULL when calling for
+ * a map operation.
+ */
 static int
 nouveau_uvmm_sm_prepare(struct nouveau_uvmm *uvmm,
 			struct nouveau_uvma_prealloc *new,
@@ -624,7 +628,7 @@ nouveau_uvmm_sm_prepare(struct nouveau_uvmm *uvmm,
 			if (ret)
 				goto unwind;
 
-			if (args && vmm_get_range) {
+			if (vmm_get_range) {
 				ret = nouveau_uvmm_vmm_get(uvmm, vmm_get_start,
 							   vmm_get_range);
 				if (ret) {
-- 
2.25.1