Date: Fri, 03 Oct 2003 13:17:59 -0400 (EDT) From: John Baldwin <jhb@FreeBSD.org> To: "M. Warner Losh" <imp@bsdimp.com> Cc: julian@elischer.org Subject: Re: PERFORCE change 38917 for review Message-ID: <XFMail.20031003131759.jhb@FreeBSD.org> In-Reply-To: <20031003.000052.96921421.imp@bsdimp.com>
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On 03-Oct-2003 M. Warner Losh wrote: > In message: <20031002022135.GA26666@perrin.nxad.com> > Hiten Pandya <hmp@nxad.com> writes: >: Does this also include PCI Hotplugging or is this going to be >: a separate effort? > > Yes and no. > > We already have removable devices in the tree. CardBus, PC Card, USB > and Firewire. Right now the drivers take liberties and chances and > there are a number of ugly races that rear their ugly heads. This is > an effort to clean that up and make things totally safe in all the > cases that we can think of, and to document those areas where we > can't. > > There's no specific plans on my part to implement the hot plug state > transition and deal with it. People have raised their hands in the > past to work on it, but so far no one has made significant progress in > public view. BTW, I thought of a locking concern in attach routines this morning. Basically, as soon as a driver does bus_setup_intr(), it needs to start using any locks shared with its interrupt handler and the hardware and driver state need to be able to handle having the handler invoked when that function is called. The reason is that the device may be attached to an interrupt line shared with another device and thus the other device may generate an interrupt and call the new devices handler before bus_setup_intr() even returns. Similarly, locking will be needed after calls to disk_create(), if_attach(), etc. -- John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/
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