Re: mpt2sas,mpt3sas watchdog device removal

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Fri, May 17, 2013 at 3:42 PM, Joe Lawrence <joe.lawrence@xxxxxxxxxxx> wrote:
> On Fri, 17 May 2013 09:29:06 -0600
> Bjorn Helgaas <bhelgaas@xxxxxxxxxx> wrote:
>
>> [+cc linux-pci]
>>
>> On Wed, May 15, 2013 at 11:29 AM, Joe Lawrence
>> <joe.lawrence@xxxxxxxxxxx> wrote:
>> > From 84ac7a35ebd61e84d4254eae78bb967de17254c2 Mon Sep 17 00:00:00
>> > 2001 From: Joe Lawrence <joe.lawrence@xxxxxxxxxxx>
>> > Date: Wed, 15 May 2013 12:52:31 -0400
>> > Subject: [PATCH] mpt2sas,mpt3sas: make watchdog instantiated device
>> > removal safe
>> >
>> > Calling pci_stop_and_remove_bus_device from a SCSI LLD may introduce
>> > device removal races with PCI callback functions.
>> >
>> > Simplify the mpt2sas watchdog mechanism by separating PCI device
>> > removal from SCSI midlayer detachment. When the watchdog wishes to
>> > remove a SCSI device from the topology, detach from the SCSI
>> > midlayer, leaving the PCI device alone. Adjust various pci_driver
>> > callbacks to account for a potentially SCSI detached PCI device.
>>
>> I don't know the details of the SCSI detachment, but this approach
>> looks much cleaner to me.
>
> Thanks for commenting, Bjorn.  I think this approach more closely
> represents what this watchdog is trying to accomplish.
>
> Off list, Sreekanth from LSI tested and noticed a few issues with this
> patch:
>
>  - mpt2sas_base_stop_watchdog is called twice: The call from
>    mpt2sas_base_detach is safe, but now unnecessary (as a call was
>    added earlier up in the PCI driver callbacks to ensure that the
>    watchdog was out of the way.) This second invocation can be removed.
>
>  - If the watchdog detects a bad IOC, the watchdog remains running:
>    The watchdog workqueue isn't cleaned up until
>    mpt2sas_base_stop_watchdog is called, so in the case that the
>    watchdog removes the device from SCSI topo, the workqueue will
>    remain unused until PCI .remove/.shutdown cleans it up. Perhaps a
>    single watchdog that iterates over all adapters would be simpler?
>
> Finally, if SCSI topo detachment is all that is interesting here, would
> it make more sense to move the watchdog into the MPT "scsi" code?  I
> haven't looked at the code yet, but this might make an MPT fusion patch
> easier (due to dependencies between its "scsi" and "base" modules).

Hi Joe,

I noticed this when looking through old email.  I can't remember if
anything happened with this.  It seems like nice work; did it go
anywhere?

Bjorn
--
To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html




[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Index of Archives]     [SCSI Target Devel]     [Linux SCSI Target Infrastructure]     [Kernel Newbies]     [IDE]     [Security]     [Git]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Linux ATA RAID]     [Linux IIO]     [Samba]     [Device Mapper]
  Powered by Linux