2020-05-27 15:56:36

by Arnd Bergmann

Subject: [PATCH 2/3] drm/i915: work around false-positive maybe-uninitialized warning

gcc-9 gets confused by the code flow in check_dirty_whitelist:

drivers/gpu/drm/i915/gt/selftest_workarounds.c: In function 'check_dirty_whitelist':
drivers/gpu/drm/i915/gt/selftest_workarounds.c:492:17: error: 'rsvd' may be used uninitialized in this function [-Werror=maybe-uninitialized]

I could not figure out a good way to do this in a way that gcc
understands better, so initialize the variable to zero, as last
resort.

Fixes: aee20aaed887 ("drm/i915: Implement read-only support in whitelist selftest")
Signed-off-by: Arnd Bergmann <[email protected]>
---
drivers/gpu/drm/i915/gt/selftest_workarounds.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/i915/gt/selftest_workarounds.c b/drivers/gpu/drm/i915/gt/selftest_workarounds.c
index 5ed323254ee1..32785463ec9e 100644
--- a/drivers/gpu/drm/i915/gt/selftest_workarounds.c
+++ b/drivers/gpu/drm/i915/gt/selftest_workarounds.c
@@ -623,6 +623,8 @@ static int check_dirty_whitelist(struct intel_context *ce)
err = -EINVAL;
goto out_unpin;
}
+ } else {
+ rsvd = 0;
}

expect = results[0];
--
2.26.2

2020-05-27 18:53:35

by Chris Wilson

Subject: Re: [PATCH 2/3] drm/i915: work around false-positive maybe-uninitialized warning

Quoting Arnd Bergmann (2020-05-27 15:05:09)
> gcc-9 gets confused by the code flow in check_dirty_whitelist:
>
> drivers/gpu/drm/i915/gt/selftest_workarounds.c: In function 'check_dirty_whitelist':
> drivers/gpu/drm/i915/gt/selftest_workarounds.c:492:17: error: 'rsvd' may be used uninitialized in this function [-Werror=maybe-uninitialized]
>
> I could not figure out a good way to do this in a way that gcc
> understands better, so initialize the variable to zero, as last
> resort.

Does it look neater if we initialise it as a local? No.
Reviewed-by: Chris Wilson <[email protected]>
-Chris