From: "Kuppuswamy, Sathyanarayanan" <sathyanarayanan.kuppuswamy@intel.com>
To: Sinan Kaya <okaya@kernel.org>,
"Zhao, Haifeng" <haifeng.zhao@intel.com>,
"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>
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 09:44:36 -0700 [thread overview]
Message-ID: <38cc8252-e485-ef11-93a1-7b43ad85fc2e@intel.com> (raw)
In-Reply-To: <16431a60-027e-eca9-36f4-74d348e88090@kernel.org>
On 9/28/20 9:43 AM, Sinan Kaya wrote:
> On 9/28/2020 7:10 AM, Sinan Kaya wrote:
>> On 9/27/2020 10:01 PM, Zhao, Haifeng wrote:
>>> 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.
>>>
>> I have been thinking about it some time but is there any reason why we
>> have to handle all port AER/DPC/HP events in different threads?
>>
>> Can we go to single threaded event loop for all port drivers events?
>>
>> This will require some refactoring but it wlll eliminate the lock
>> nightmares we are having.
>>
>> This means no sleeping. All sleeps need to happen outside of the loop.
>>
>> I wanted to see what you all are thinking about this.
>>
>> It might become a performance problem if the system is
>> continuously observing a hotplug/aer/dpc events.
>>
>> I always think that these should be rare events.
> If restructuring would be too costly, the preferred solution should be
> to fix the locks in hotplug driver rather than throwing there a random
> wait call.
Since the current race condition is detected between DPC and
hotplug, I recommend synchronizing them.
--
Sathyanarayanan Kuppuswamy
Linux Kernel Developer
next prev parent reply other threads:[~2020-09-28 16:44 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
2020-09-28 11:10 ` Sinan Kaya
2020-09-28 16:43 ` Sinan Kaya
2020-09-28 16:44 ` Kuppuswamy, Sathyanarayanan [this message]
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=38cc8252-e485-ef11-93a1-7b43ad85fc2e@intel.com \
--to=sathyanarayanan.kuppuswamy@intel.com \
--cc=andriy.shevchenko@linux.intel.com \
--cc=ashok.raj@linux.intel.com \
--cc=bhelgaas@google.com \
--cc=haifeng.zhao@intel.com \
--cc=keith.busch@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pci@vger.kernel.org \
--cc=lukas@wunner.de \
--cc=mika.westerberg@linux.intel.com \
--cc=mr.nuke.me@gmail.com \
--cc=okaya@kernel.org \
--cc=oohall@gmail.com \
--cc=pei.p.jia@intel.com \
--cc=ruscur@russell.cc \
--cc=stuart.w.hayes@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).