Re: [PATCH v4 05/16] ufs: core: mcq: Add Multi Circular Queue support

Bart Van Assche
2022-11-09T21:16:25Z

On 11/9/22 11:41, Asutosh Das wrote:
> +static int ufshcd_mcq_config_nr_queues(struct ufs_hba *hba)
> +{
> + int i;
> + u32 hba_maxq, rem, tot_queues;
> + struct Scsi_Host *host = hba->host;
> +
> + hba_maxq = FIELD_GET(GENMASK(7, 0), hba->mcq_capabilities);
> +
> + if (!rw_queues)
> + rw_queues = num_possible_cpus();
> +
> + tot_queues = UFS_MCQ_NUM_DEV_CMD_QUEUES + read_queues + poll_queues +
> + rw_queues;
> +
> + if (hba_maxq < tot_queues) {
> + dev_err(hba->dev, "Total queues (%d) exceeds HC capacity (%d)\n",
> + tot_queues, hba_maxq);
> + return -EOPNOTSUPP;
> + }

This function can fail with default kernel module parameters, e.g.
num_possible_cpus() == 8 and hba_maxq == 4. This is not acceptable. A
better solution is required, e.g. reducing rw_queues if the user has not
set this kernel module parameter.

Thanks,

Bart.