Date: Sun, 14 Jan 2007 02:25:04 +0100 From: Hans Petter Selasky <hselasky@c2i.net> To: "M. Warner Losh" <imp@bsdimp.com> Cc: perforce@freebsd.org Subject: Re: PERFORCE change 112835 for review Message-ID: <200701140225.05299.hselasky@c2i.net> In-Reply-To: <20070113.122940.420518338.imp@bsdimp.com> References: <200701122132.l0CLWuAG096027@repoman.freebsd.org> <20070113.122940.420518338.imp@bsdimp.com>
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On Saturday 13 January 2007 20:29, M. Warner Losh wrote: > In message: <200701122132.l0CLWuAG096027@repoman.freebsd.org> > > Hans Petter Selasky <hselasky@freebsd.org> writes: > : http://perforce.freebsd.org/chv.cgi?CH=112835 > : > : Change 112835 by hselasky@hselasky_mini_itx on 2007/01/12 21:32:24 > : > : ether_ifattach() must be called without any mutexes held, hence > : it can sleep. Use generated typedef's for prototypes for exported > : device methods. This prevents invalid parameter passing and return. > > Why do the attach methods even have locked mutexes to drop? That was > a common error in the early locking efforts that too many network > drivers inherited. Maybe the right fix is to just remove the > lock/unlock pairs in attach entirely... > The attach code in question is run from a separate config thread, which by default locks "sc->sc_mtx" before calling the callback function. Therefore the code unlocks that lock, to avoid sleeping with mutex locked errors. Probably all of the attach code can run without "sc->sc_mtx" locked, but will require Giant locked, when changing the device tree, for example when adding new child devices like MII-bus instances. --HPS
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