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From: "Zhao, Haifeng" <haifeng.zhao@intel.com>
To: Sinan Kaya <okaya@kernel.org>,
	"bhelgaas@google.com" <bhelgaas@google.com>,
	"oohall@gmail.com" <oohall@gmail.com>,
	"ruscur@russell.cc" <ruscur@russell.cc>,
	"lukas@wunner.de" <lukas@wunner.de>,
	"andriy.shevchenko@linux.intel.com" 
	<andriy.shevchenko@linux.intel.com>,
	"stuart.w.hayes@gmail.com" <stuart.w.hayes@gmail.com>,
	"mr.nuke.me@gmail.com" <mr.nuke.me@gmail.com>,
	"mika.westerberg@linux.intel.com"
	<mika.westerberg@linux.intel.com>,
	Keith Busch <keith.busch@intel.com>
Cc: "linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"Jia, Pei P" <pei.p.jia@intel.com>,
	"ashok.raj@linux.intel.com" <ashok.raj@linux.intel.com>,
	"Kuppuswamy,
	Sathyanarayanan" <sathyanarayanan.kuppuswamy@intel.com>
Subject: RE: [PATCH 2/5 V2] PCI: pciehp: check and wait port status out of DPC before handling DLLSC and PDC
Date: Mon, 28 Sep 2020 02:01:34 +0000	[thread overview]
Message-ID: <MWHPR11MB1696BA6B8473248A8638FD3797350@MWHPR11MB1696.namprd11.prod.outlook.com> (raw)
In-Reply-To: <f2c9e3db-2027-f669-fcdd-fbc80888b934@kernel.org>

Sinan,
   I explained the reason why locks don't protect this case in the patch description part. 
Write side and read side hold different semaphore and mutex.

Thanks,
Ethan

-----Original Message-----
From: Sinan Kaya <okaya@kernel.org> 
Sent: Sunday, September 27, 2020 11:28 PM
To: Zhao, Haifeng <haifeng.zhao@intel.com>; bhelgaas@google.com; oohall@gmail.com; ruscur@russell.cc; lukas@wunner.de; andriy.shevchenko@linux.intel.com; stuart.w.hayes@gmail.com; mr.nuke.me@gmail.com; mika.westerberg@linux.intel.com; Keith Busch <keith.busch@intel.com>
Cc: linux-pci@vger.kernel.org; linux-kernel@vger.kernel.org; Jia, Pei P <pei.p.jia@intel.com>; ashok.raj@linux.intel.com; Kuppuswamy, Sathyanarayanan <sathyanarayanan.kuppuswamy@intel.com>
Subject: Re: [PATCH 2/5 V2] PCI: pciehp: check and wait port status out of DPC before handling DLLSC and PDC

On 9/26/2020 11:28 PM, Ethan Zhao wrote:
> diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
> index 53433b37e181..6f271160f18d 100644
> --- a/drivers/pci/hotplug/pciehp_hpc.c
> +++ b/drivers/pci/hotplug/pciehp_hpc.c
> @@ -710,8 +710,10 @@ static irqreturn_t pciehp_ist(int irq, void *dev_id)
>  	down_read(&ctrl->reset_lock);
>  	if (events & DISABLE_SLOT)
>  		pciehp_handle_disable_request(ctrl);
> -	else if (events & (PCI_EXP_SLTSTA_PDC | PCI_EXP_SLTSTA_DLLSC))
> +	else if (events & (PCI_EXP_SLTSTA_PDC | PCI_EXP_SLTSTA_DLLSC)) {
> +		pci_wait_port_outdpc(pdev);
>  		pciehp_handle_presence_or_link_change(ctrl, events);
> +	}
>  	up_read(&ctrl->reset_lock);

This looks like a hack TBH.

Lukas, Keith;

What is your take on this?
Why is device lock not protecting this situation?

Is there a lock missing in hotplug driver?

Sinan

  reply	other threads:[~2020-09-28  2:14 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-27  3:28 [PATCH 0/5 V2] Fix DPC hotplug race and enhance error handling Ethan Zhao
2020-09-27  3:28 ` [PATCH 1/5 V2] PCI: define a function to check and wait till port finish DPC handling Ethan Zhao
2020-09-27  6:23   ` Christoph Hellwig
2020-09-27  6:43     ` Zhao, Haifeng
2020-09-29  2:32     ` Ethan Zhao
2020-09-27  3:28 ` [PATCH 2/5 V2] PCI: pciehp: check and wait port status out of DPC before handling DLLSC and PDC Ethan Zhao
2020-09-27 15:27   ` Sinan Kaya
2020-09-28  2:01     ` Zhao, Haifeng [this message]
2020-09-28 11:10       ` Sinan Kaya
2020-09-28 16:43         ` Sinan Kaya
2020-09-28 16:44           ` Kuppuswamy, Sathyanarayanan
2020-09-29  2:28             ` Ethan Zhao
2020-09-29  2:50           ` Ethan Zhao
2020-09-29  8:18     ` Lukas Wunner
2020-09-29  9:46       ` Ethan Zhao
2020-09-29 10:07         ` Lukas Wunner
2020-09-30  2:20           ` Ethan Zhao
2020-09-27  3:28 ` [PATCH 3/5 V2] PCI/ERR: get device before call device driver to avoid NULL pointer reference Ethan Zhao
2020-09-27  3:28 ` [PATCH 4/5 V2] PCI: only return true when dev io state is really changed Ethan Zhao
2020-09-27  4:16   ` Joe Perches
2020-09-27  5:12     ` Zhao, Haifeng
2020-09-27  3:28 ` [PATCH 5/5 V2] PCI/ERR: don't mix io state not changed and no driver together Ethan Zhao

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