Received-SPF: pass (google.com: domain of linux-kernel+bounces-189762-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:4601:e00::3 as permitted sender) client-ip=2604:1380:4601:e00::3;
Content-Type: text/plain;
	charset=utf-8
Precedence: bulk
Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3696.120.41.1.1\))
Subject: Re: [PATCH] PCI: pciehp: Use appropriate conditions to check the
 hotplug controller status
From: yaoma <yaoma@linux.alibaba.com>
In-Reply-To: <ZlBHjbmjjSEnXCMp@wunner.de>
Date: Sun, 26 May 2024 22:45:36 +0800
Cc: yaoma <yaoma@linux.alibaba.com>,
 bhelgaas@google.com,
 weirongguang@kylinos.cn,
 kanie@linux.alibaba.com,
 linux-pci@vger.kernel.org,
 linux-kernel@vger.kernel.org
Content-Transfer-Encoding: quoted-printable
Message-Id: <7855600C-4BB6-417B-8F91-24F4F7E0820E@linux.alibaba.com>
References: <20240524063023.77148-1-yaoma@linux.alibaba.com>
 <ZlBHjbmjjSEnXCMp@wunner.de>
To: Lukas Wunner <lukas@wunner.de>

Hi,

> 2024=E5=B9=B45=E6=9C=8824=E6=97=A5 15:53=EF=BC=8CLukas Wunner =
<lukas@wunner.de> =E5=86=99=E9=81=93=EF=BC=9A
>=20
> On Fri, May 24, 2024 at 02:30:23PM +0800, Bitao Hu wrote:
>> The values of 'present' and 'link_active' have similar meanings:
>> the value is %1 if the status is ready, and %0 if it is not. If the
>> hotplug controller itself is not available, the value should be
>> %-ENODEV. However, both %1 and %-ENODEV are considered true, which
>> obviously does not meet expectations. 'Slot(xx): Card present' and
>> 'Slot(xx): Link Up' should only be output when the value is %1.
> [...]
>> --- a/drivers/pci/hotplug/pciehp_ctrl.c
>> +++ b/drivers/pci/hotplug/pciehp_ctrl.c
>> @@ -276,10 +276,10 @@ void =
pciehp_handle_presence_or_link_change(struct controller *ctrl, u32 =
events)
>> 	case OFF_STATE:
>> 		ctrl->state =3D POWERON_STATE;
>> 		mutex_unlock(&ctrl->state_lock);
>> -		if (present)
>> +		if (present > 0)
>> 			ctrl_info(ctrl, "Slot(%s): Card present\n",
>> 				  slot_name(ctrl));
>> -		if (link_active)
>> +		if (link_active > 0)
>> 			ctrl_info(ctrl, "Slot(%s): Link Up\n",
>> 				  slot_name(ctrl));
>> 		ctrl->request_result =3D pciehp_enable_slot(ctrl);
>=20
> We already handle the "<=3D 0" case immediately above this code =
excerpt:
>=20
> 	if (present <=3D 0 && link_active <=3D 0) {
> 	...
> 	}
I'm not sure if the following scenarios would occur in actual production =
environment,
but from the code level, there is the possibility of =E2=80=9Cpresent <=3D=
 0 && link_active > 0=E2=80=9D
or =E2=80=9Cpresent > 0 && link_active <=3D 0=E2=80=9D. In these cases, =
the =E2=80=9C<=3D 0=E2=80=9D conditions will
not be properly handled, and =E2=80=9Cctrl_info=E2=80=9D will output =
incorrect prompt messages.
> So neither "present" nor "link_active" can be < 0 at this point.
>=20
Best Regards,

	Bitao Hu=