Hi Sam,
Thanks for review.
On Sat, Apr 20, 2024 at 10:32:02AM +0200, Sam Ravnborg wrote:
> On Sat, Apr 20, 2024 at 01:15:46PM +0800, Dawei Li wrote:
> > In general it's preferable to avoid placing cpumasks on the stack, as
> > for large values of NR_CPUS these can consume significant amounts of
> > stack space and make stack overflows more likely.
> >
> > Use cpumask_subset() and cpumask_first_and() to avoid the need for a
> > temporary cpumask on the stack.
> >
> > Signed-off-by: Dawei Li <dawei.li@xxxxxxxxxxxx>
> > ---
> > arch/sparc/kernel/leon_kernel.c | 9 +++------
> > 1 file changed, 3 insertions(+), 6 deletions(-)
> >
> > diff --git a/arch/sparc/kernel/leon_kernel.c b/arch/sparc/kernel/leon_kernel.c
> > index 4c61da491fee..0070655041bb 100644
> > --- a/arch/sparc/kernel/leon_kernel.c
> > +++ b/arch/sparc/kernel/leon_kernel.c
> > @@ -106,13 +106,10 @@ unsigned long leon_get_irqmask(unsigned int irq)
> > #ifdef CONFIG_SMP
> > static int irq_choose_cpu(const struct cpumask *affinity)
> > {
> > - cpumask_t mask;
> > + unsigned int cpu = cpumask_first_and(affinity, cpu_online_mask);
> >
> > - cpumask_and(&mask, cpu_online_mask, affinity);
> > - if (cpumask_equal(&mask, cpu_online_mask) || cpumask_empty(&mask))
> > - return boot_cpu_id;
> > - else
> > - return cpumask_first(&mask);
> > + return cpumask_subset(cpu_online_mask, affinity) || cpu >= nr_cpu_ids ?
> > + boot_cpu_id : cpu;
>
> This looks wrong - or if it is correct is is hard to parse.
> Drop ?: and use an if so the code is more readable.
I am confused a bit here, about its correctness(not coding style).
Per my understanding:
A & B = A <-> For every set bit in A, it's set for B; <-> B is superset
of A. <-> A is subset of B.
- cpumask_and(&mask, cpu_online_mask, affinity);
- if (cpumask_equal(&mask, cpu_online_mask))
So, codes above is equivalent to:
if (cpumask_subset(cpu_online_mask, affinity))
Am I missing something?
About the ?:, I will restore original "if else" style.
>
> Sam
>
Thanks,
Dawei
