Re: [RFC PATCH v7 5/8] ice: implement dpll interface to control cgu

[Jiri Pirko <jiri@resnulli.us>]

Tue, May 16, 2023 at 12:07:57AM CEST, arkadiusz.kubalewski@intel.com wrote:
>>From: Jiri Pirko <jiri@resnulli.us>
>>Sent: Wednesday, May 3, 2023 2:19 PM
>>
>>Fri, Apr 28, 2023 at 02:20:06AM CEST, vadfed@meta.com wrote:
>>>From: Arkadiusz Kubalewski <arkadiusz.kubalewski@intel.com>

[...]


>>>+ * ice_dpll_frequency_set - wrapper for pin callback for set frequency
>>>+ * @pin: pointer to a pin
>>>+ * @pin_priv: private data pointer passed on pin registration
>>>+ * @dpll: pointer to dpll
>>>+ * @frequency: frequency to be set
>>>+ * @extack: error reporting
>>>+ * @pin_type: type of pin being configured
>>>+ *
>>>+ * Wraps internal set frequency command on a pin.
>>>+ *
>>>+ * Return:
>>>+ * * 0 - success
>>>+ * * negative - error pin not found or couldn't set in hw  */ static
>>>+int ice_dpll_frequency_set(const struct dpll_pin *pin, void *pin_priv,
>>>+		       const struct dpll_device *dpll,
>>>+		       const u32 frequency,
>>>+		       struct netlink_ext_ack *extack,
>>>+		       const enum ice_dpll_pin_type pin_type) {
>>>+	struct ice_pf *pf = pin_priv;
>>>+	struct ice_dpll_pin *p;
>>>+	int ret = -EINVAL;
>>>+
>>>+	if (!pf)
>>>+		return ret;
>>>+	if (ice_dpll_cb_lock(pf))
>>>+		return -EBUSY;
>>>+	p = ice_find_pin(pf, pin, pin_type);
>>
>>This does not make any sense to me. You should avoid the lookups and remove
>>ice_find_pin() function entirely. The purpose of having pin_priv is to
>>carry the struct ice_dpll_pin * directly. You should pass it down during
>>pin register.
>>
>>pf pointer is stored in dpll_priv.
>>
>
>In this case dpll_priv is not passed, so cannot use it.

It should be passed. In general to every op where *dpll is passed, the
dpll_priv pointer should be passed along. Please, fix this.


>But in general it makes sense I will hold pf inside of ice_dpll_pin
>and fix this.

Nope, just use dpll_priv. That's why we have it.


[...]


>>>+/**
>>>+ * ice_dpll_pin_state_set - set pin's state on dpll
>>>+ * @dpll: dpll being configured
>>>+ * @pin: pointer to a pin
>>>+ * @pin_priv: private data pointer passed on pin registration
>>>+ * @state: state of pin to be set
>>>+ * @extack: error reporting
>>>+ * @pin_type: type of a pin
>>>+ *
>>>+ * Set pin state on a pin.
>>>+ *
>>>+ * Return:
>>>+ * * 0 - OK or no change required
>>>+ * * negative - error
>>>+ */
>>>+static int
>>>+ice_dpll_pin_state_set(const struct dpll_device *dpll,
>>>+		       const struct dpll_pin *pin, void *pin_priv,
>>>+		       const enum dpll_pin_state state,
>>
>>Why you use const with enums?
>>
>
>Just show usage intention explicitly.

Does not make any sense what so ever. Please avoid it.


>>>+static int ice_dpll_rclk_state_on_pin_get(const struct dpll_pin *pin,
>>>+					  void *pin_priv,
>>>+					  const struct dpll_pin *parent_pin,
>>>+					  enum dpll_pin_state *state,
>>>+					  struct netlink_ext_ack *extack) {
>>>+	struct ice_pf *pf = pin_priv;
>>>+	u32 parent_idx, hw_idx = ICE_DPLL_PIN_IDX_INVALID, i;
>>
>>Reverse christmas tree ordering please.
>
>Fixed.
>
>>
>>
>>>+	struct ice_dpll_pin *p;
>>>+	int ret = -EFAULT;
>>>+
>>>+	if (!pf)
>>
>>How exacly this can happen. My wild guess is it can't. Don't do such
>>pointless checks please, confuses the reader.
>>
>
>From driver perspective the pf pointer value is given by external entity,
>why shouldn't it be valdiated?

What? You pass it during register, you get it back here. Nothing to
check. Please drop it. Non-sense checks like this have no place in
kernel, they only confuse reader as he/she assumes it is a valid case.


[...]


>>
>>
>>>+			pins[i].pin = NULL;
>>>+			return -ENOMEM;
>>>+		}
>>>+		if (cgu) {
>>>+			ret = dpll_pin_register(pf->dplls.eec.dpll,
>>>+						pins[i].pin,
>>>+						ops, pf, NULL);
>>>+			if (ret)
>>>+				return ret;
>>>+			ret = dpll_pin_register(pf->dplls.pps.dpll,
>>>+						pins[i].pin,
>>>+						ops, pf, NULL);
>>>+			if (ret)
>>>+				return ret;
>>
>>You have to call dpll_pin_unregister(pf->dplls.eec.dpll, pins[i].pin, ..)
>>here.
>>
>
>No, in case of error, the caller releases everything ice_dpll_release_all(..).


How does ice_dpll_release_all() where you failed? If you need to
unregister one or both or none? I know that in ice you have odd ways to
handle error paths in general, but this one clearly seems to be broken.





>
>>
>>>+		}
>>>+	}
>>>+	if (cgu) {
>>>+		ops = &ice_dpll_output_ops;
>>>+		pins = pf->dplls.outputs;
>>>+		for (i = 0; i < pf->dplls.num_outputs; i++) {
>>>+			pins[i].pin = dpll_pin_get(pf->dplls.clock_id,
>>>+						   i + pf->dplls.num_inputs,
>>>+						   THIS_MODULE, &pins[i].prop);
>>>+			if (IS_ERR_OR_NULL(pins[i].pin)) {
>>>+				pins[i].pin = NULL;
>>>+				return -ENOMEM;
>>
>>Don't make up error values when you get them from the function you call:
>>	return PTR_ERR(pins[i].pin);
>
>Fixed.
>
>>
>>>+			}
>>>+			ret = dpll_pin_register(pf->dplls.eec.dpll, pins[i].pin,
>>>+						ops, pf, NULL);
>>>+			if (ret)
>>>+				return ret;
>>>+			ret = dpll_pin_register(pf->dplls.pps.dpll, pins[i].pin,
>>>+						ops, pf, NULL);
>>>+			if (ret)
>>>+				return ret;
>>
>>You have to call dpll_pin_unregister(pf->dplls.eec.dpll, pins[i].pin, ..)
>>here.
>>
>
>As above, in case of error, the caller releases everything.

As above, I don't think it works.


[...]


>>>+	}
>>>+
>>>+	if (cgu) {
>>>+		ret = dpll_device_register(pf->dplls.eec.dpll, DPLL_TYPE_EEC,
>>>+					   &ice_dpll_ops, pf, dev);
>>>+		if (ret)
>>>+			goto put_pps;
>>>+		ret = dpll_device_register(pf->dplls.pps.dpll, DPLL_TYPE_PPS,
>>>+					   &ice_dpll_ops, pf, dev);
>>>+		if (ret)
>>
>>You are missing call to dpll_device_unregister(pf->dplls.eec.dpll,
>>DPLL_TYPE_EEC here. Fix the error path.
>>
>
>The caller shall do the clean up, but yeah will fix this as here clean up
>is not expected.

:) Just make your error paths obvious and easy to follow to not to
confuse anybody, you included.


>
>>
>>>+			goto put_pps;
>>>+	}
>>>+
>>>+	return 0;
>>>+
>>>+put_pps:
>>>+	dpll_device_put(pf->dplls.pps.dpll);
>>>+	pf->dplls.pps.dpll = NULL;
>>>+put_eec:
>>>+	dpll_device_put(pf->dplls.eec.dpll);
>>>+	pf->dplls.eec.dpll = NULL;
>>>+
>>>+	return ret;
>>>+}

[...]