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SubjectRe: [PATCH] [v3] x86: kvm: avoid -Wsometimes-uninitized warning
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On Fri, Jul 12, 2019 at 04:13:09PM +0200, Arnd Bergmann wrote:
> Clang notices a code path in which some variables are never
> initialized, but fails to figure out that this can never happen
> on i386 because is_64_bit_mode() always returns false.
>
> arch/x86/kvm/hyperv.c:1610:6: error: variable 'ingpa' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
> if (!longmode) {
> ^~~~~~~~~
> arch/x86/kvm/hyperv.c:1632:55: note: uninitialized use occurs here
> trace_kvm_hv_hypercall(code, fast, rep_cnt, rep_idx, ingpa, outgpa);
> ^~~~~
> arch/x86/kvm/hyperv.c:1610:2: note: remove the 'if' if its condition is always true
> if (!longmode) {
> ^~~~~~~~~~~~~~~
> arch/x86/kvm/hyperv.c:1595:18: note: initialize the variable 'ingpa' to silence this warning
> u64 param, ingpa, outgpa, ret = HV_STATUS_SUCCESS;
> ^
> = 0
> arch/x86/kvm/hyperv.c:1610:6: error: variable 'outgpa' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
> arch/x86/kvm/hyperv.c:1610:6: error: variable 'param' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
>
> Flip the condition around to avoid the conditional execution on i386.
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> v3: reword commit log, simplify patch again
> v2: make the change inside of is_64_bit_mode().
> ---
> arch/x86/kvm/hyperv.c | 20 +++++++++-----------
> 1 file changed, 9 insertions(+), 11 deletions(-)

Reviewed-by: Roman Kagan <rkagan@virtuozzo.com>

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