From: Jiang Liu <jiang.liu@huawei.com>
To: Greg KH <gregkh@linuxfoundation.org>
Cc: Jiang Liu <liuj97@gmail.com>, Yinghai Lu <yinghai@kernel.org>,
Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>,
Bjorn Helgaas <bhelgaas@google.com>,
Don Dutile <ddutile@redhat.com>,
Keping Chen <chenkeping@huawei.com>,
linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org
Subject: Re: [PATCH v2 04/19] PCI: serialize hotplug operations triggered by PCI hotplug sysfs interfaces
Date: Wed, 02 May 2012 15:20:15 +0800 [thread overview]
Message-ID: <4FA0E02F.5040901@huawei.com> (raw)
In-Reply-To: <20120502050625.GB23579@kroah.com>
On 2012-5-2 13:06, Greg KH wrote:
> On Fri, Apr 27, 2012 at 11:16:45PM +0800, Jiang Liu wrote:
>> + /* Avoid deadlock with pci_hp_deregister() */
>> + while (!pci_hotplug_try_enter()) {
>> + /* Check whether the slot has been deregistered. */
>> + if (list_empty(&slot->slot_list)) {
>> + retval = -ENODEV;
>> + goto exit_put;
>> + }
>> + msleep(1);
>> + }
>
> Oh my.
>
> Wow.
>
> {sigh}
>
> ick.
>
> My eyes hurt.
>
> And your cpu load just went crazy.
>
> You can now handle all of the nasty emails from sysadmins asking why
> their systems look like their load is high for no good reason.
My bad, should use schedule_timeout_interruptible() instead of
msleep(1) here to avoid busy waiting.
>
> Not to mention all of the other issues here.
>
> My statement about not inventing new lock types has now been proven
> true.
>
> The fact that this would even be a chunk of code that was proposed to be
> merged makes me weep.
>
> You owe me a bottle of whatever you are drinking if you expect me to
> continue to review these patch submissions.
>
> I'm stopping here in the series, please rework this whole thing in a
> major way.
>
> greg k-h
>
>
next prev parent reply other threads:[~2012-05-02 7:22 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-27 15:16 [PATCH v2 00/19] Introduce a global lock to serialize all PCI hotplug Jiang Liu
2012-04-27 15:16 ` [PATCH v2 01/19] PCI: introduce pci_bus_get()/pci_bus_put() to hide PCI implementation details Jiang Liu
2012-04-27 15:16 ` [PATCH v2 02/19] PCI: introduce recursive rwsem to serialize PCI hotplug operations Jiang Liu
2012-05-02 5:00 ` Greg KH
2012-05-02 7:25 ` Jiang Liu
2012-05-02 21:46 ` Greg KH
2012-04-27 15:16 ` [PATCH v2 03/19] PCI: replace pci_remove_rescan_mutex with the PCI hotplug lock Jiang Liu
2012-04-27 15:16 ` [PATCH v2 04/19] PCI: serialize hotplug operations triggered by PCI hotplug sysfs interfaces Jiang Liu
2012-05-02 5:06 ` Greg KH
2012-05-02 7:20 ` Jiang Liu [this message]
2012-05-02 21:48 ` Greg KH
2012-04-27 15:16 ` [PATCH v2 05/19] PCI: correctly flush workqueue when destroy pcie hotplug controller Jiang Liu
2012-05-02 5:08 ` Greg KH
2012-04-27 15:16 ` [PATCH v2 06/19] PCI: prepare for serializing hotplug operations triggered by pciehp driver Jiang Liu
2012-05-02 5:10 ` Greg KH
2012-04-27 15:16 ` [PATCH v2 07/19] PCI: serialize hotplug operaitons triggered by the " Jiang Liu
2012-04-27 15:16 ` [PATCH v2 08/19] PCI: fix two race windows when probing/removing SHPC controller Jiang Liu
2012-04-27 15:16 ` [PATCH v2 09/19] PCI: correctly flush workqueues and timer when destroy " Jiang Liu
2012-04-27 15:16 ` [PATCH v2 10/19] PCI: serialize hotplug operaitons triggered by the shpchp driver Jiang Liu
2012-04-27 15:16 ` [PATCH v2 11/19] PCI: release IO resource in error handling path in cpcihp_generic_init() Jiang Liu
2012-04-27 15:16 ` [PATCH v2 12/19] PCI: clean up all resources in error handling path in zt5550_hc_init_one() Jiang Liu
2012-04-27 15:16 ` [PATCH v2 13/19] PCI: trivial code clean up in cpci_hotplug_core.c Jiang Liu
2012-04-27 15:16 ` [PATCH v2 14/19] PCI: fix race windows when shutting down cpcihp controller Jiang Liu
2012-04-27 15:16 ` [PATCH v2 15/19] PCI: hold a reference count to the PCI bus used by cpcihp drivers Jiang Liu
2012-04-27 15:16 ` [PATCH v2 16/19] PCI: serialize PCI hotplug operations triggered " Jiang Liu
2012-04-27 15:16 ` [PATCH v2 17/19] PCI: serialize PCI hotplug operations triggered by fakephp drivers Jiang Liu
2012-04-27 15:16 ` [PATCH v2 18/19] PCI, sysfs: Use device_type and attr_groups with pci dev Jiang Liu
2012-04-27 15:17 ` [PATCH v2 19/19] PCI: hide sys interface 'remove' and 'rescan' for SR-IOV virtual devices Jiang Liu
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