Re: [PATCH 4.9 1/2] iommu/amd: Fix backport of 140456f994195b568ecd7fc2287a34eadffef3ca

[Joerg Roedel <joro@8bytes.org>]

On Tue, Jul 27, 2021 at 03:56:49PM -0700, Nathan Chancellor wrote:
> Clang warns:
> 
> drivers/iommu/amd_iommu.c:1335:6: warning: variable 'flags' is used
> uninitialized whenever 'if' condition is true
> [-Wsometimes-uninitialized]
>         if (!pte)
>             ^~~~
> drivers/iommu/amd_iommu.c:1352:40: note: uninitialized use occurs here
>         spin_unlock_irqrestore(&domain->lock, flags);
>                                               ^~~~~
> drivers/iommu/amd_iommu.c:1335:2: note: remove the 'if' if its condition
> is always false
>         if (!pte)
>         ^~~~~~~~~
> drivers/iommu/amd_iommu.c:1331:21: note: initialize the variable 'flags'
> to silence this warning
>         unsigned long flags;
>                            ^
>                             = 0
> 1 warning generated.
> 
> The backport of commit 140456f99419 ("iommu/amd: Fix sleeping in atomic
> in increase_address_space()") to 4.9 as commit 1d648460d7c5 ("iommu/amd:
> Fix sleeping in atomic in increase_address_space()") failed to keep the
> "return false", which in 4.9 needs to be a regular "return" due to a
> lack of commit f15d9a992f90 ("iommu/amd: Remove domain->updated").
> 
> This resolves the warning and matches the 4.14-4.19 backport.
> 
> Cc: Andrey Ryabinin <arbn@yandex-team.com>
> Cc: Joerg Roedel <joro@8bytes.org>
> Cc: Will Deacon <will@kernel.org>
> Fixes: 1d648460d7c5 ("iommu/amd: Fix sleeping in atomic in increase_address_space()")
> Reported-by: kernel test robot <lkp@intel.com>
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>

Acked-by: Joerg Roedel <jroedel@suse.de>