2023-01-22 09:33:03

by Paolo Bonzini

Subject: [PATCH] selftests: kvm: move declaration at the beginning of main()

Placing a declaration of evt_reset is pedantically invalid
according to the C standard. While GCC does not really care
and only warns with -Wpedantic, clang ignores the declaration
altogether with an error:

x86_64/xen_shinfo_test.c:965:2: error: expected expression
struct kvm_xen_hvm_attr evt_reset = {
^
x86_64/xen_shinfo_test.c:969:38: error: use of undeclared identifier evt_reset
vm_ioctl(vm, KVM_XEN_HVM_SET_ATTR, &evt_reset);
^

Reported-by: Yu Zhang <[email protected]>
Reported-by: Sean Christopherson <[email protected]>
Fixes: a79b53aaaab5 ("KVM: x86: fix deadlock for KVM_XEN_EVTCHN_RESET", 2022-12-28)
Signed-off-by: Paolo Bonzini <[email protected]>
---
tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c b/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c
index dae510c263b4..13c75dc18c10 100644
--- a/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c
+++ b/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c
@@ -434,6 +434,7 @@ static void *juggle_shinfo_state(void *arg)
int main(int argc, char *argv[])
{
struct timespec min_ts, max_ts, vm_ts;
+ struct kvm_xen_hvm_attr evt_reset;
struct kvm_vm *vm;
pthread_t thread;
bool verbose;
@@ -962,10 +963,8 @@ int main(int argc, char *argv[])
}

done:
- struct kvm_xen_hvm_attr evt_reset = {
- .type = KVM_XEN_ATTR_TYPE_EVTCHN,
- .u.evtchn.flags = KVM_XEN_EVTCHN_RESET,
- };
+ evt_reset.type = KVM_XEN_ATTR_TYPE_EVTCHN;
+ evt_reset.u.evtchn.flags = KVM_XEN_EVTCHN_RESET;
vm_ioctl(vm, KVM_XEN_HVM_SET_ATTR, &evt_reset);

alarm(0);
--
2.39.0

2023-01-23 16:28:21

by David Matlack

Subject: Re: [PATCH] selftests: kvm: move declaration at the beginning of main()

On Sun, Jan 22, 2023 at 1:09 AM Paolo Bonzini <[email protected]> wrote:
>
> Placing a declaration of evt_reset is pedantically invalid
> according to the C standard. While GCC does not really care
> and only warns with -Wpedantic, clang ignores the declaration
> altogether with an error:
>
> x86_64/xen_shinfo_test.c:965:2: error: expected expression
> struct kvm_xen_hvm_attr evt_reset = {
> ^
> x86_64/xen_shinfo_test.c:969:38: error: use of undeclared identifier evt_reset
> vm_ioctl(vm, KVM_XEN_HVM_SET_ATTR, &evt_reset);
> ^
>
> Reported-by: Yu Zhang <[email protected]>
> Reported-by: Sean Christopherson <[email protected]>
> Fixes: a79b53aaaab5 ("KVM: x86: fix deadlock for KVM_XEN_EVTCHN_RESET", 2022-12-28)
> Signed-off-by: Paolo Bonzini <[email protected]>

Thanks, I had a similar patch queued up to send out today :)

Can you add clang to your workflow for queueing patches? It's not the
first time a selftest patch that does not build with clang has snuck
into kvm/queue or even an rc [1].

[1] git log --oneline --grep Fixes: --grep clang --all-match
tools/testing/selftests/kvm