| Message ID | 171d1da4-e87a-b154-5c63-a5627d4f93bc@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | fix build when NR_CPUS == 1 | expand |
Jan Beulich writes ("[PATCH 1/2][4.15?] sched: fix build when NR_CPUS == 1"):
> In this case the compiler is recognizing that no valid array indexes
> remain, and hence e.g. reports:
Release-Acked-by: Ian Jackson <iwj@xenproject.org>
On Mon, 2021-03-01 at 15:57 +0000, Ian Jackson wrote: > Jan Beulich writes ("[PATCH 1/2][4.15?] sched: fix build when NR_CPUS > == 1"): > > In this case the compiler is recognizing that no valid array > > indexes > > remain, and hence e.g. reports: > > Release-Acked-by: Ian Jackson <iwj@xenproject.org> > Reviewed-by: Dario Faggioli <dfaggioli@suse.com> Regards
--- a/xen/common/sched/core.c +++ b/xen/common/sched/core.c @@ -2768,6 +2768,12 @@ static int cpu_schedule_up(unsigned int if ( cpu == 0 ) return 0; + /* + * Guard in particular against the compiler suspecting out-of-bounds + * array accesses below when NR_CPUS=1. + */ + BUG_ON(cpu >= NR_CPUS); + if ( idle_vcpu[cpu] == NULL ) vcpu_create(idle_vcpu[0]->domain, cpu); else
In this case the compiler is recognizing that no valid array indexes remain, and hence e.g. reports: core.c: In function 'cpu_schedule_up': core.c:2769:19: error: array subscript 1 is above array bounds of 'struct vcpu *[1]' [-Werror=array-bounds] 2769 | if ( idle_vcpu[cpu] == NULL ) | ~~~~~~~~~^~~~~ Reported-by: Connor Davis <connojdavis@gmail.com> Signed-off-by: Jan Beulich <jbeulich@suse.com>