2009/5/21 Kostik Belousov <kostikbel@gmail.com>:
> On Thu, May 21, 2009 at 01:22:07PM +0000, Attilio Rao wrote:
>> Author: attilio
>> Date: Thu May 21 13:22:07 2009
>> New Revision: 192535
>> URL: http://svn.freebsd.org/changeset/base/192535
>>
>> Log:
>> Move the M_WAITOK flag in notify() into an M_NOWAIT one in order to match
>> the behaviour alredy present with the further malloc() call in
>> devctl_notify().
>> This fixes a bug in the CAM layer where the camisr handler finished to
>> call camperiphfree() (and subsequently destroy_dev() resulting in a new
>> dev notify) while the xpt lock is held.
> This is wrong. You cannot call destroy_dev() while holding any mutex.
> Taking this into account, it makes no sense to use M_NOWAIT in notify().
As long as devctl_notify() also calls M_NOWAIT and if not available
skips "silently" it just does the same thing, I think this approach is
more consistent.
It remains, though, the fact to fix CAM when calling destroy_dev().
Maybe we should add a witness_warn() there?
Thanks,
Attilio
--
Peace can only be achieved by understanding - A. Einstein