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From: "Krzysztof Wilczyński" <kw@linux.com>
To: Dongdong Liu <liudongdong3@huawei.com>
Cc: helgaas@kernel.org, hch@infradead.org, logang@deltatee.com,
	leon@kernel.org, linux-pci@vger.kernel.org, rajur@chelsio.com,
	hverkuil-cisco@xs4all.nl, linux-media@vger.kernel.org,
	netdev@vger.kernel.org
Subject: Re: [PATCH V9 4/8] PCI/sysfs: Add a 10-Bit Tag sysfs file PCIe Endpoint devices
Date: Thu, 23 Sep 2021 06:21:57 +0200	[thread overview]
Message-ID: <YUwA5eC7wiDoHy0F@rocinante> (raw)
In-Reply-To: <20210922133655.51811-5-liudongdong3@huawei.com>

Hi,

Thank you for sending the patch over!  A few small comments below.

[...]
> +static ssize_t pci_10bit_tag_store(struct device *dev,
> +				   struct device_attribute *attr,
> +				   const char *buf, size_t count)
> +{
> +	struct pci_dev *pdev = to_pci_dev(dev);
> +	bool enable;

Would you mind adding the following capabilities check here?

	if (!capable(CAP_SYS_ADMIN))
		return -EPERM;

This is so we make sure that whatever user is going to use this sysfs
attribute actually has enough permissions to update this value safely.

> +	if (kstrtobool(buf, &enable) < 0)
> +		return -EINVAL;
> +
> +	if (pdev->driver)
> +		return -EBUSY;
> +
> +	if (enable) {
> +		if (!pcie_rp_10bit_tag_cmp_supported(pdev))
> +			return -EPERM;

Would it make sense to also verify 10-Bit Tag Completer support on the
"disable" path too?   We won't be able to set a value if there is no
support, but nothing will stop us from clearing it regardless - unless
this would be safe to do?  What do you think?

> +		pcie_capability_set_word(pdev, PCI_EXP_DEVCTL2,
> +				PCI_EXP_DEVCTL2_10BIT_TAG_REQ_EN);
> +	} else {
> +		pcie_capability_clear_word(pdev, PCI_EXP_DEVCTL2,
> +				   PCI_EXP_DEVCTL2_10BIT_TAG_REQ_EN);
> +	}
> +
> +	return count;
> +}

[...]
> +> +static umode_t pcie_dev_10bit_tag_attrs_are_visible(struct kobject *kobj,
> +					  struct attribute *a, int n)

The preferred function name for the .is_visible() callback in a case when
there is only a single sysfs attribute being added would be:

  pcie_dev_10bit_tag_attr_is_visible()

Albeit, I appreciate that you followed the existing naming pattern.

	Krzysztof

  reply	other threads:[~2021-09-23  4:22 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-22 13:36 [PATCH V9 0/8] PCI: Enable 10-Bit tag support for PCIe devices Dongdong Liu
2021-09-22 13:36 ` [PATCH V9 1/8] PCI: Use cached devcap in more places Dongdong Liu
2021-09-22 13:36 ` [PATCH V9 2/8] PCI: Cache Device Capabilities 2 Register Dongdong Liu
2021-09-22 13:36 ` [PATCH V9 3/8] PCI: Add 10-Bit Tag register definitions Dongdong Liu
2021-09-22 13:36 ` [PATCH V9 4/8] PCI/sysfs: Add a 10-Bit Tag sysfs file PCIe Endpoint devices Dongdong Liu
2021-09-23  4:21   ` Krzysztof Wilczyński [this message]
2021-09-23 11:06     ` Dongdong Liu
2021-09-22 13:36 ` [PATCH V9 5/8] PCI/IOV: Add 10-Bit Tag sysfs files for VF devices Dongdong Liu
2021-09-22 13:36 ` [PATCH V9 6/8] PCI/P2PDMA: Add a 10-Bit Tag check in P2PDMA Dongdong Liu
2021-09-22 13:36 ` [PATCH V9 7/8] PCI: Enable 10-Bit Tag support for PCIe Endpoint device Dongdong Liu
2021-09-22 13:36 ` [PATCH V9 8/8] PCI/IOV: Enable 10-Bit Tag support for PCIe VF devices Dongdong Liu

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