Re: [PATCHv13 10/11] nvme: register fdp parameters with the block layer

John Garry
2024-12-11T09:31:22Z

On 10/12/2024 19:47, Keith Busch wrote:
>
> +static int nvme_query_fdp_granularity(struct nvme_ctrl *ctrl,
> + struct nvme_ns_info *info, u8 fdp_idx)
> +{
> + struct nvme_fdp_config_log hdr, *h;
> + struct nvme_fdp_config_desc *desc;
> + size_t size = sizeof(hdr);
> + int i, n, ret;
> + void *log;
> +
> + ret = nvme_get_log_lsi(ctrl, 0, NVME_LOG_FDP_CONFIGS, 0,
> + NVME_CSI_NVM, &hdr, size, 0, info->endgid);
> + if (ret) {
> + dev_warn(ctrl->device,
> + "FDP configs log header status:0x%x endgid:%x\n", ret,
> + info->endgid);

About endgid, I guess that there is a good reason but sometimes "0x" is
prefixed for hex prints and sometimes not. Maybe no prefix is used when
we know that the variable is to hold a value from a HW register / memory
structure - I don't know.

further nitpicking: And ret holds a kernel error code - the driver seems
inconsistent for printing this. Sometimes it's %d and sometimes 0x%x.

> + return ret;
> + }
> +
> + size = le32_to_cpu(hdr.sze);
> + h = kzalloc(size, GFP_KERNEL);
> + if (!h) {
> + dev_warn(ctrl->device,
> + "failed to allocate %lu bytes for FDP config log\n",
> + size);

do we normally print ENOMEM messages? I see that the bytes is printed,
but I assume that this is a sane value (of little note).

> + return -ENOMEM;
> + }
> +
> + ret = nvme_get_log_lsi(ctrl, 0, NVME_LOG_FDP_CONFIGS, 0,
> + NVME_CSI_NVM, h, size, 0, info->endgid);
> + if (ret) {
> + dev_warn(ctrl->device,
> + "FDP configs log status:0x%x endgid:%x\n", ret,
> + info->endgid);
> + goto out;
> + }
> +
> + n = le16_to_cpu(h->numfdpc) + 1;
> + if (fdp_idx > n) {
> + dev_warn(ctrl->device, "FDP index:%d out of range:%d\n",
> + fdp_idx, n);
> + /* Proceed without registering FDP streams */> + ret = 0;

nit: maybe you want to be explicit, but logically ret is already 0

> + goto out;
> + }
> +
> + log = h + 1;
> + desc = log;
> + for (i = 0; i < fdp_idx; i++) {
> + log += le16_to_cpu(desc->dsze);
> + desc = log;
> + }
> +
> + if (le32_to_cpu(desc->nrg) > 1) {
> + dev_warn(ctrl->device, "FDP NRG > 1 not supported\n");
> + ret = 0;

Same here

> + goto out;
> + }
> +
> + info->runs = le64_to_cpu(desc->runs);
> +out:
> + kfree(h);
> + return ret;
> +}