On Fri, Sep 18, 2015 at 03:55:00PM +0200, Paolo Bonzini wrote:
>
>
> On 18/09/2015 15:51, Denis V. Lunev wrote:
> >> 185
> >> > 186 task_cputime_adjusted(current, &utime, &stime);
> >> 187 return div_u64(cputime_to_nsecs(utime + stime), 100);
> >> 188 }
> >> 189
> >> 190 static int kvm_hv_set_msr(struct kvm_vcpu *vcpu, u32 msr,
> >> u64 data, bool host)
> >> 191 {
> >> 192 struct kvm_vcpu_hv *hv = &vcpu->arch.hyperv;
> >> 193
> >> 194 switch (msr) {
> >>
> >> ---
> >> 0-DAY kernel test infrastructure Open Source Technology
> >> Center
> >> https://lists.01.org/pipermail/kbuild-all Intel
> >> Corporation
> > can not get an idea what is this warning about...
> > For me it looks pretty lame.
>
> I think it wants you to do
>
> - return div_u64(cputime_to_nsecs(utime + stime), 100);
> + return div_u64(cputime_to_nsecs(utime) +
> + cputime_to_nsecs(stime), 100);
The warning is pretty specific about the point where it triggered.
I have reduced it to the following standalone reproducer:
%%% cat x.c
#ifdef __CHECKER__
# define __nocast __attribute__((nocast))
#else
# define __nocast
#endif
typedef unsigned long __nocast cputime_t;
extern void task_cputime_adjusted(cputime_t *);
extern void current_task_runtime_100ns(void);
void current_task_runtime_100ns(void)
{
cputime_t utime;
task_cputime_adjusted(&utime);
}
%%% gcc -c x.c -Wall -Werror -O2; echo $?
0
%%% sparse x.c
x.c:16:32: warning: incorrect type in argument 1 (different modifiers)
x.c:16:32: expected unsigned long [nocast] [usertype] *<noident>
x.c:16:32: got unsigned long *<noident>
x.c:16:32: warning: implicit cast to nocast type
Looks like a sparse bug to me.
Roman.
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