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Date: Mon, 27 Jul 2026 12:13:56 +0200
From: Lukas Wunner <lukas@wunner.de>
To: ZhaoJinming <zhaojinming@uniontech.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>, linux-pci@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>,
	Dragan Simic <dsimic@manjaro.org>,
	Shawn Lin <shawn.lin@rock-chips.com>, Kees Cook <kees@kernel.org>,
	Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
Subject: Re: [PATCH] PCI/ASPM: Add missing NULL check for link in sysfs
 show/store callbacks
Message-ID: <amcvZMBxMFB5ild0@wunner.de>
References: <20260727072915.3954329-1-zhaojinming@uniontech.com>
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In-Reply-To: <20260727072915.3954329-1-zhaojinming@uniontech.com>

On Mon, Jul 27, 2026 at 03:29:15PM +0800, ZhaoJinming wrote:
> The aspm_attr_show_common(), aspm_attr_store_common(), clkpm_show()
> and clkpm_store() sysfs callbacks call pcie_aspm_get_link() without
> checking the return value. A NULL return would indicate the device is
> not PCIe, has no upstream bridge, or the link state has not been
> initialized.
> 
> While the aspm_ctrl_attrs_are_visible() is_visible callback already
> hides these attributes when link is NULL, add the NULL check for
> defense in depth and consistency with other callers of
> pcie_aspm_get_link() in the same file (__pci_disable_link_state,
> __pci_enable_link_state, pcie_aspm_enabled).

Well, if we don't need the checks because the ->is_visible() callback
already hides the attributes, then we shouldn't add them.

Otherwise it's quite possible that someone else comes along and deletes
the checks again because they're superfluous.  

Thanks,

Lukas