[PATCH] drm/i915/gvt: fix uninitialized return in intel_gvt_update_reg_whitelist()

[PATCH] drm/i915/gvt: fix uninitialized return in intel_gvt_update_reg_whitelist()

[Dan Carpenter]

Smatch found an uninitialized variable bug in this code:

    drivers/gpu/drm/i915/gvt/cmd_parser.c:3191 intel_gvt_update_reg_whitelist()
    error: uninitialized symbol 'ret'.

The first thing that Smatch complains about is that "ret" isn't set if
we don't enter the "for_each_engine(engine, &dev_priv->gt, id) {" loop.
Presumably we always have at least one engine so that's a false
positive.

But it's definitely a bug to not set "ret" if i915_gem_object_pin_map()
fails.

Let's fix the bug and silence the false positive.

Fixes: 493f30cd086e ("drm/i915/gvt: parse init context to update cmd accessible reg whitelist")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
 drivers/gpu/drm/i915/gvt/cmd_parser.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gvt/cmd_parser.c b/drivers/gpu/drm/i915/gvt/cmd_parser.c
index 7fb91de06557..d54ea0e4681d 100644
--- a/drivers/gpu/drm/i915/gvt/cmd_parser.c
+++ b/drivers/gpu/drm/i915/gvt/cmd_parser.c
@@ -3103,7 +3103,7 @@ void intel_gvt_update_reg_whitelist(struct intel_vgpu *vgpu)
 	struct intel_vgpu_submission *s = &vgpu->submission;
 	struct i915_request *requests[I915_NUM_ENGINES] = {};
 	bool is_ctx_pinned[I915_NUM_ENGINES] = {};
-	int ret;
+	int ret = 0;
 
 	if (gvt->is_reg_whitelist_updated)
 		return;
@@ -3157,6 +3157,7 @@ void intel_gvt_update_reg_whitelist(struct intel_vgpu *vgpu)
 		if (IS_ERR(vaddr)) {
 			gvt_err("failed to pin init ctx obj, ring=%d, err=%lx\n",
 				id, PTR_ERR(vaddr));
+			ret = PTR_ERR(vaddr);
 			goto out;
 		}
 
-- 
2.29.2

Re: [PATCH] drm/i915/gvt: fix uninitialized return in intel_gvt_update_reg_whitelist()

[Chris Wilson]

Quoting Dan Carpenter (2021-01-25 08:48:30)
> Smatch found an uninitialized variable bug in this code:
> 
>     drivers/gpu/drm/i915/gvt/cmd_parser.c:3191 intel_gvt_update_reg_whitelist()
>     error: uninitialized symbol 'ret'.
> 
> The first thing that Smatch complains about is that "ret" isn't set if
> we don't enter the "for_each_engine(engine, &dev_priv->gt, id) {" loop.
> Presumably we always have at least one engine so that's a false
> positive.
> 
> But it's definitely a bug to not set "ret" if i915_gem_object_pin_map()
> fails.

True.
 
> Let's fix the bug and silence the false positive.
> 
> Fixes: 493f30cd086e ("drm/i915/gvt: parse init context to update cmd accessible reg whitelist")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
-Chris

Re: [PATCH] drm/i915/gvt: fix uninitialized return in intel_gvt_update_reg_whitelist()

[Zhenyu Wang]

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On 2021.01.25 09:44:53 +0000, Chris Wilson wrote:
> Quoting Dan Carpenter (2021-01-25 08:48:30)
> > Smatch found an uninitialized variable bug in this code:
> > 
> >     drivers/gpu/drm/i915/gvt/cmd_parser.c:3191 intel_gvt_update_reg_whitelist()
> >     error: uninitialized symbol 'ret'.
> > 
> > The first thing that Smatch complains about is that "ret" isn't set if
> > we don't enter the "for_each_engine(engine, &dev_priv->gt, id) {" loop.
> > Presumably we always have at least one engine so that's a false
> > positive.
> > 
> > But it's definitely a bug to not set "ret" if i915_gem_object_pin_map()
> > fails.
> 
> True.
>  
> > Let's fix the bug and silence the false positive.
> > 
> > Fixes: 493f30cd086e ("drm/i915/gvt: parse init context to update cmd accessible reg whitelist")
> > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>

Thanks, Dan & Chris! Queued this up.

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