linux-kernel - Re: [PATCH] Revert "PCI: Fix reference leak in pci_register_host

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Message-ID: <4a967093-97e2-401f-a0ea-9d7447d518c4@nfschina.com>
Date: Thu, 10 Apr 2025 19:19:17 +0800
From: Su Hui <suhui@...china.com>
To: Xiangwei Li <liwei728@...wei.com>
Cc: linux-kernel@...r.kernel.org, make24@...as.ac.cn, bhelgaas@...gle.com,
 linux-pci@...r.kernel.org, bobo.shaobowang@...wei.com,
 wangxiongfeng2@...wei.com
Subject: Re: [PATCH] Revert "PCI: Fix reference leak in
 pci_register_host_bridge()"

On 2025/4/10 11:28, Xiangwei Li wrote:
> This reverts commit 804443c1f27883926de94c849d91f5b7d7d696e9.
>
> The newly added logic incorrectly sets bus_registered to true even when
> device_register returns an error, this is incorrect.
>
> When device_register fails, there is no need to release the reference count,
I think you missed some thing about device_register(). This patch is wrong.

device_register()
     -> device_initialize()
               -> kobject_init()
                     -> kobject_init_internal()
                         -> kref_init(&kobj->kref);  //set 
kref->refcount to 1
                            ^^^^^^^^^^^^^^^^^^^^^

device_register() only  fails when device_add() fails, and 
kerf->refcount can be 1
at this time ,  so we need to call put_deivce() to release  memory.
> and there are no direct error-handling operations following its execution.
>
> Therefore, this patch is meaningless and should be reverted.
>
> Fixes: 804443c1f278 ("PCI: Fix reference leak in pci_register_host_bridge()")
> Signed-off-by: Xiangwei Li <liwei728@...wei.com>
> Signed-off-by: Xiongfeng Wang <wangxiongfeng2@...wei.com>