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SubjectRe: [PATCH v4 1/3] soc: qcom: Introduce Protection Domain Restart helpers
On Wed 26 Feb 08:59 PST 2020, Sibi Sankar wrote:
> diff --git a/drivers/soc/qcom/Kconfig b/drivers/soc/qcom/Kconfig
[..]
> +config QCOM_PDR_HELPERS
> + tristate
> + depends on ARCH_QCOM || COMPILE_TEST

As discussed on one of you other patches, please omit the depends on for
Kconfig entries that are not user selectable. Presumably anyone
selecting this option will have ARCH_QCOM met already.

> + select QCOM_QMI_HELPERS
[..]
> diff --git a/drivers/soc/qcom/pdr_interface.c b/drivers/soc/qcom/pdr_interface.c
[..]
> +static void pdr_locator_work(struct work_struct *work)
> +{
> + struct pdr_handle *pdr = container_of(work, struct pdr_handle,
> + locator_work);
> + struct pdr_service *pds;
> + int ret = 0;
> +
> + /* Bail out early if the SERVREG LOCATOR QMI service is not up */
> + mutex_lock(&pdr->lock);
> + if (!pdr->locator_init_complete) {
> + mutex_unlock(&pdr->lock);
> + pr_debug("PDR: SERVICE LOCATOR service not available\n");
> + return;
> + }
> + mutex_unlock(&pdr->lock);
> +
> + mutex_lock(&pdr->list_lock);
> + list_for_each_entry(pds, &pdr->lookups, node) {
> + if (!pds->need_locator_lookup)
> + continue;
> +
> + pds->need_locator_lookup = false;
> + mutex_unlock(&pdr->list_lock);
> +
> + ret = pdr_locate_service(pdr, pds);
> + if (ret < 0)
> + goto exit;
> +
> + /* Initialize notifier QMI handle */
> + mutex_lock(&pdr->lock);
> + if (!pdr->notifier_init_complete) {
> + ret = qmi_handle_init(&pdr->notifier_hdl,
> + SERVREG_STATE_UPDATED_IND_MAX_LEN,
> + &pdr_notifier_ops,
> + qmi_indication_handler);
> + if (ret < 0) {
> + mutex_unlock(&pdr->lock);
> + goto exit;
> + }
> + pdr->notifier_init_complete = true;
> + }
> + mutex_unlock(&pdr->lock);
> +
> + ret = qmi_add_lookup(&pdr->notifier_hdl, pds->service, 1,
> + pds->instance);
> + if (ret < 0)
> + goto exit;
> +
> + return;

If the caller calls pdr_add_lookup() multiple times in quick succession
wouldn't it be possile to get the worker scheduled with multiple entries
in &pdr->lookups with need_locator_lookup set?

If so I think it makes sense to break the content of this loop, and the
error handling under exit out into a separate function.

And even if this would not be the case, breaking this out in a separate
function would allow you to change the loop to:

list_for_each_entry() {
if (pdr->need_locator_lookup) {
do_the_lookup();
break;
}
}

Which I think is easier to reason about than the loop with a return at
the end.

> + }
> + mutex_unlock(&pdr->list_lock);
> +exit:
> + if (ret < 0) {
> + /* Notify lookup failed */
> + mutex_lock(&pdr->list_lock);
> + list_del(&pds->node);
> + mutex_unlock(&pdr->list_lock);
> +
> + if (ret == -ENXIO)
> + pds->state = SERVREG_LOCATOR_UNKNOWN_SERVICE;
> + else
> + pds->state = SERVREG_LOCATOR_ERR;
> +
> + pr_err("PDR: service lookup for %s failed: %d\n",
> + pds->service_name, ret);
> +
> + mutex_lock(&pdr->status_lock);
> + pdr->status(pds->state, pds->service_path, pdr->priv);
> + mutex_unlock(&pdr->status_lock);
> + kfree(pds);
> + }
> +}
[..]
> +struct pdr_handle *pdr_handle_alloc(void (*status)(int state,
> + char *service_path,
> + void *priv), void *priv)
> +{
> + struct pdr_handle *pdr;
> + int ret;
> +
> + if (!status)
> + return ERR_PTR(-EINVAL);
> +
> + pdr = kzalloc(sizeof(*pdr), GFP_KERNEL);
> + if (!pdr)
> + return ERR_PTR(-ENOMEM);
> +
> + pdr->status = *status;

Please omit the * here.

Regards,
Bjorn

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