On 9/16/24 4:55 AM, Felix Moessbauer wrote:
> Putting the cpumask on the stack is deprecated for a long time (since
> 2d3854a37e8), as these can be big. Given that, we port-over the stack
> allocated mask to the cpumask allocation api.
I'd change that last sentence to:
Given that, change the on-stack allocation of allowed_mask to be
dynamically allocated.
> diff --git a/io_uring/sqpoll.c b/io_uring/sqpoll.c
> index 7adfcf6818ff..44b9f58e11b6 100644
> --- a/io_uring/sqpoll.c
> +++ b/io_uring/sqpoll.c
> @@ -461,15 +461,22 @@ __cold int io_sq_offload_create(struct io_ring_ctx *ctx,
> return 0;
>
> if (p->flags & IORING_SETUP_SQ_AFF) {
> - struct cpumask allowed_mask;
> + cpumask_var_t allowed_mask;
> int cpu = p->sq_thread_cpu;
>
> ret = -EINVAL;
> if (cpu >= nr_cpu_ids || !cpu_online(cpu))
> goto err_sqpoll;
> - cpuset_cpus_allowed(current, &allowed_mask);
> - if (!cpumask_test_cpu(cpu, &allowed_mask))
> + if (!alloc_cpumask_var(&allowed_mask, GFP_KERNEL)) {
> + ret = -ENOMEM;
> goto err_sqpoll;
> + }
> + cpuset_cpus_allowed(current, allowed_mask);
> + if (!cpumask_test_cpu(cpu, allowed_mask)) {
> + free_cpumask_var(allowed_mask);
> + goto err_sqpoll;
> + }
> + free_cpumask_var(allowed_mask);
> sqd->sq_cpu = cpu;
The kernel generally does:
ret = -ESOMEERROR;
if (fails_check)
goto err_label;
and you're now mixing the two here. To keep it consistent, it'd be
better to do :
ret = -ENOMEM before the alloc, and then re-set it to -EINVAL before the
cpumask check.
--
Jens Axboe
