Messages in this thread | | | Date | Mon, 30 Mar 2020 16:35:40 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH] sched/vtime: Fix an unitialized variable warning |
| |
On Fri, Mar 27, 2020 at 10:43:34PM +0100, Borislav Petkov wrote: > Hi dude, > > right before I was going to send the trivial, shut-up-gcc variant, I > thought that maybe we should do this instead. > > Thoughts? > > --- > Fix: > > kernel/sched/cputime.c: In function ‘kcpustat_field’: > kernel/sched/cputime.c:1007:6: warning: ‘val’ may be used \ > uninitialized in this function [-Wmaybe-uninitialized] > 1007 | u64 val; > | ^~~ > > because gcc can't see that val is used only when err is 0. > > Signed-off-by: Borislav Petkov <bp@suse.de> > --- > kernel/sched/cputime.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c > index dac9104d126f..ff9435dee1df 100644 > --- a/kernel/sched/cputime.c > +++ b/kernel/sched/cputime.c > @@ -1003,12 +1003,12 @@ u64 kcpustat_field(struct kernel_cpustat *kcpustat, > enum cpu_usage_stat usage, int cpu) > { > u64 *cpustat = kcpustat->cpustat; > + u64 val = cpustat[usage]; > struct rq *rq; > - u64 val; > int err; > > if (!vtime_accounting_enabled_cpu(cpu)) > - return cpustat[usage]; > + return val; > > rq = cpu_rq(cpu);
Hurph.. this might result in an unconditional load (and extra cache-miss) for the vtime_accounting_enabled_cpu() case.
I suspesct the =0 this would be better. Stupid stupid compiler!
| |