Re: [PATCH V2 net-next 01/21] net-next/hinic: Initialize hw interface

Hi Francois,

ERR_PTR / IS ERR - we will change it

err_xyz labels - we will change it according to other companies style.

hinic_free_hwdev - It is there to mark us changes for VF code. We will remove it,
it can't be failed.

hinic_remove - If insmod failed and someone calls rmmod, we will get a crash because
the resource are already free. Therefore we test if the device exists, please tell me
if you meant to something different

pci_id_tbl - will be moved to the .c file.

void* - usually void * is something to avoid.

The priv data is in type void * because the
caller can use any struct that it wants, like the priv data in Linux
(netdev, irq, tasklet, work..) -

we can change it but if we will pass different struct
in the future, we will have to change the prototype of the functions.

According to the other void *:
The wq struct is used for cmdq, sq and rq. Therefore the wqe is in type
void *. There are 4 operations get_wqe, write_wqe, read_wqe and put_wqe - there
is no option that one function will be fed with a wrong pointer because the caller
should use what it got in get_wqe function.

When something is used as multiple types, it can be used as void * or union.
Usually, I would prefer union. But, in this case if we will use union, maybe there is a chance
of using the wrong wqe type in the wrong work queue type.
Another option is to use a wrapper for each wq type operations, so only the basic wq ops will
use void *.

Then, there will be cmdq, rq, sq operations with the correct wqe type and wq operations that
will use void *.

I will be glad to hear your opinion about the preferred style and about hinic_remove issue you mentioned
above.

Thanks for your time and review,
Aviad



On 7/20/2017 1:27 AM, Francois Romieu wrote:

Aviad Krawczyk [off-list ref] :
[...]

quoted

diff --git a/drivers/net/ethernet/huawei/hinic/hinic_hw_dev.c b/drivers/net/ethernet/huawei/hinic/hinic_hw_dev.c
new file mode 100644
index 0000000..fbc9de4
--- /dev/null
+++ b/drivers/net/ethernet/huawei/hinic/hinic_hw_dev.c

[...]

quoted

+/**
+ * hinic_init_hwdev - Initialize the NIC HW
+ * @hwdev: the NIC HW device that is returned from the initialization
+ * @pdev: the NIC pci device
+ *
+ * Return 0 - Success, negative - Failure
+ *
+ * Initialize the NIC HW device and return a pointer to it in the first arg
+ **/

Return a pointer and use ERR_PTR / IS_ERR ?

quoted

+int hinic_init_hwdev(struct hinic_hwdev **hwdev, struct pci_dev *pdev)
+{
+	struct hinic_pfhwdev *pfhwdev;
+	struct hinic_hwif *hwif;
+	int err;
+
+	hwif = devm_kzalloc(&pdev->dev, sizeof(*hwif), GFP_KERNEL);
+	if (!hwif)
+		return -ENOMEM;
+
+	err = hinic_init_hwif(hwif, pdev);
+	if (err) {
+		dev_err(&pdev->dev, "Failed to init HW interface\n");
+		return err;
+	}
+
+	if (!HINIC_IS_PF(hwif) && !HINIC_IS_PPF(hwif)) {
+		dev_err(&pdev->dev, "Unsupported PCI Function type\n");
+		err = -EFAULT;
+		goto func_type_err;
+	}
+
+	pfhwdev = devm_kzalloc(&pdev->dev, sizeof(*pfhwdev), GFP_KERNEL);
+	if (!pfhwdev) {
+		err = -ENOMEM;
+		goto pfhwdev_alloc_err;

Intel, Mellanox, Broadcom, Amazon and friends use "err_xyz" labels.

Please consider using the same style.

[...]

quoted

+void hinic_free_hwdev(struct hinic_hwdev *hwdev)
+{
+	struct hinic_hwif *hwif = hwdev->hwif;
+	struct pci_dev *pdev = hwif->pdev;
+	struct hinic_pfhwdev *pfhwdev;
+
+	if (!HINIC_IS_PF(hwif) && !HINIC_IS_PPF(hwif)) {
+		dev_err(&pdev->dev, "unsupported PCI Function type\n");
+		return;
+	}

If it succeeded in hinic_init_hwdev, how could it fail here ?

If it failed in hinic_init_hwdev, hinic_free_hwdev should not even
be called.

-> remove ?

[...]

quoted

diff --git a/drivers/net/ethernet/huawei/hinic/hinic_main.c b/drivers/net/ethernet/huawei/hinic/hinic_main.c
new file mode 100644
index 0000000..c61c769
--- /dev/null
+++ b/drivers/net/ethernet/huawei/hinic/hinic_main.c

[...]

quoted

+static void hinic_remove(struct pci_dev *pdev)
+{
+	struct net_device *netdev = pci_get_drvdata(pdev);
+	struct hinic_dev *nic_dev;
+
+	if (!netdev)
+		return;

Your driver is flawed if this test can ever succeed.

[...]

quoted

+static int __init hinic_init(void)
+{
+	return pci_register_driver(&hinic_driver);
+}
+
+static void __exit hinic_exit(void)
+{
+	pci_unregister_driver(&hinic_driver);
+}

Use module_pci_driver(hinic_driver).

Remove hinic_init() and hinic_exit().

quoted

diff --git a/drivers/net/ethernet/huawei/hinic/hinic_pci_id_tbl.h b/drivers/net/ethernet/huawei/hinic/hinic_pci_id_tbl.h
new file mode 100644
index 0000000..1d92617
--- /dev/null
+++ b/drivers/net/ethernet/huawei/hinic/hinic_pci_id_tbl.h

[...]

quoted

+#ifndef HINIC_PCI_ID_TBL_H
+#define HINIC_PCI_ID_TBL_H
+
+#ifndef PCI_VENDOR_ID_HUAWEI
+#define PCI_VENDOR_ID_HUAWEI            0x19e5
+#endif

Useless: it duplicates include/linux/pci_ids.h

quoted

+
+#ifndef PCI_DEVICE_ID_HI1822_PF
+#define PCI_DEVICE_ID_HI1822_PF         0x1822
+#endif

Please move it to the .c file where it is actually used.


Extra:

grep -E 'void\ \*' drivers/net/ethernet/huawei/hinic/* makes me nervous.

At some point one function will be fed with a wrong pointer and the
compiler won't notice it.

For instance hinic_sq_read_wqe is only called with &skb. There's no
reason to declare it using a 'void **' argument.