On Dec 18, 2017, at 16:01, NeilBrown <ne...@suse.com> wrote: > > Calling smp_processor_id() without disabling preemption > triggers a warning (if CONFIG_DEBUG_PREEMPT). > I think the result of cfs_cpt_current() is only used as a hint for > load balancing, rather than as a precise and stable indicator of > the current CPU. So it doesn't need to be called with > preemption disabled. > > So disable preemption inside cfs_cpt_current() to silence the warning. > > Signed-off-by: NeilBrown <ne...@suse.com>
Reviewed-by: Andreas Dilger <andreas.dil...@intel.com> > --- > .../staging/lustre/lnet/libcfs/linux/linux-cpu.c | 13 +++++++------ > 1 file changed, 7 insertions(+), 6 deletions(-) > > diff --git a/drivers/staging/lustre/lnet/libcfs/linux/linux-cpu.c > b/drivers/staging/lustre/lnet/libcfs/linux/linux-cpu.c > index d30650f8dcb4..ca8518b8a3e0 100644 > --- a/drivers/staging/lustre/lnet/libcfs/linux/linux-cpu.c > +++ b/drivers/staging/lustre/lnet/libcfs/linux/linux-cpu.c > @@ -517,19 +517,20 @@ EXPORT_SYMBOL(cfs_cpt_spread_node); > int > cfs_cpt_current(struct cfs_cpt_table *cptab, int remap) > { > - int cpu = smp_processor_id(); > - int cpt = cptab->ctb_cpu2cpt[cpu]; > + int cpu; > + int cpt; > > - if (cpt < 0) { > - if (!remap) > - return cpt; > + preempt_disable(); > + cpu = smp_processor_id(); > + cpt = cptab->ctb_cpu2cpt[cpu]; > > + if (cpt < 0 && remap) { > /* don't return negative value for safety of upper layer, > * instead we shadow the unknown cpu to a valid partition ID > */ > cpt = cpu % cptab->ctb_nparts; > } > - > + preempt_enable(); > return cpt; > } > EXPORT_SYMBOL(cfs_cpt_current); > > Cheers, Andreas -- Andreas Dilger Lustre Principal Architect Intel Corporation