linux-kernel - Re: [PATCH v2] selftests/iommu: prevent use of uninitialized variable

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Message-ID: <20250926130237.GA2695987@ziepe.ca>
Date: Fri, 26 Sep 2025 10:02:37 -0300
From: Jason Gunthorpe <jgg@...pe.ca>
To: Alessandro Zanni <alessandro.zanni87@...il.com>
Cc: kevin.tian@...el.com, shuah@...nel.org, iommu@...ts.linux.dev,
	linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] selftests/iommu: prevent use of uninitialized variable

On Wed, Sep 24, 2025 at 07:16:28PM +0200, Alessandro Zanni wrote:
> Fix to avoid the usage of the `res` variable uninitialized in the
> following macro expansions.
> 
> It solves the following warning:
> In function ‘iommufd_viommu_vdevice_alloc’,
>   inlined from ‘wrapper_iommufd_viommu_vdevice_alloc’ at
> iommufd.c:2889:1:
> ../kselftest_harness.h:760:12: warning: ‘ret’ may be used uninitialized
> [-Wmaybe-uninitialized]
>   760 |   if (!(__exp _t __seen)) { \
>       |      ^
> ../kselftest_harness.h:513:9: note: in expansion of macro ‘__EXPECT’
>   513 |   __EXPECT(expected, #expected, seen, #seen, ==, 1)
>       |   ^~~~~~~~
> iommufd_utils.h:1057:9: note: in expansion of macro ‘ASSERT_EQ’
>  1057 |   ASSERT_EQ(0, _test_cmd_trigger_vevents(self->fd, dev_id,
> nvevents))
>       |   ^~~~~~~~~
> iommufd.c:2924:17: note: in expansion of macro
> ‘test_cmd_trigger_vevents’
>  2924 |   test_cmd_trigger_vevents(dev_id, 3);
>       |   ^~~~~~~~~~~~~~~~~~~~~~~~

Shouldn't word wrap output like this, ignore the checkpatch warnings.

> The issue can be reproduced, building the tests, with the command:
> make -C tools/testing/selftests TARGETS=iommu

    Fixes: 97717a1f283f ("iommufd/selftest: Add IOMMU_VEVENTQ_ALLOC test coverage")

Applied, thanks

Jason