From mboxrd@z Thu Jan  1 00:00:00 1970
From: Doug Ledford <dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Subject: Re: [PATCH for-next] iw_cxgb4: Fix possible circular dependency
 locking warning
Date: Mon, 13 Nov 2017 16:59:39 -0500
Message-ID: <1510610379.3735.44.camel@redhat.com>
References: <1510229853-25875-1-git-send-email-bharat@chelsio.com>
         <012b01d35969$48d7d9a0$da878ce0$@opengridcomputing.com>
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To: Steve Wise <swise-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>, 'Potnuri Bharat Teja' <bharat-ut6Up61K2wZBDgjK7y7TUQ@public.gmane.org>
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On Thu, 2017-11-09 at 08:44 -0600, Steve Wise wrote:
> >=20
> > Locking sequence of iw_cxgb4 and RoCE drivers in ib_register_device() i=
s
> > slightly different and this leads to possible circular dependency locki=
ng
> > warning when both the devices are brought up.
> >=20
> > Here is the locking sequence upto ib_register_device():
> > iw_cxgb4: rtnl_mutex(net stack) --> uld_mutex --> device_mutex
> > RoCE drivers: device_mutex --> rtnl_mutex
> >=20
> > Here is the possibility of cross locking:
> >=20
> > 	CPU #0 (iw_cxgb4) 		     CPU #1 (RoCE drivers)
> >=20
> > -> on interface up cxgb4_up()
> > executed with rtnl_mutex held
> > -> hold uld_mutex and try
> > registering ib device
> > 					-> In ib_register_device() hold
> > 					   device_mutex
> > -> hold device mutex in
> > ib_register_device
> > 					-> try acquiring rtnl_mutex in
> > 					   ib_enum_roce_netdev()
> >=20
> > Current patch schedules the ib_register_device() functionality of
> > iw_cxgb4 to a workqueue to prevent the possible cross-locking.
> > Also rename the labels in c4iw_reister_device().
> >=20
> > Signed-off-by: Potnuri Bharat Teja <bharat-ut6Up61K2wZBDgjK7y7TUQ@public.gmane.org>
>=20
> Reviewed-by: Steve Wise <swise-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>
>=20
>=20

Thanks, applied.

--=20
Doug Ledford <dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
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