Re: [PATCH 3/3] Add disk hotswap support to libata RESEND #2

From: George Anzinger
Date: Tue Aug 23 2005 - 18:00:50 EST


Jim Ramsay wrote:
On 8/23/05, Jim Ramsay <jim.ramsay@xxxxxxxxx> wrote:

Then I must have found an undocumented feature! I've applied this set
of patches to a 2.6.11 kernel (with few problems) and ran into a bunch
of "scheduling while atomic" errors when hotplugging a drive, culprit
being probably scsi_sysfs.c where scsi_remove_device locks a mutex, or
perhaps when it then calls class_device_unregister, which does a
'down_write'.


After further debugging, it appears that the problem is the debounce
timer in libata-core.c.

Timers appear to operate in an atomic context, so timers should not be
allowed to call scsi_remove_device, which eventually schedules.

Any suggestions on the best way to fix this?

Workqueue, perhaps.


--
George Anzinger george@xxxxxxxxxx
HRT (High-res-timers): http://sourceforge.net/projects/high-res-timers/
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