Date: Mon, 19 Jun 2006 09:15:50 -0400 From: John Baldwin <jhb@freebsd.org> To: Ian Dowse <iedowse@iedowse.com> Cc: cvs-src@freebsd.org, src-committers@freebsd.org, cvs-all@freebsd.org Subject: Re: cvs commit: src/sys/sys firmware.h src/sys/kern subr_firmware.c Message-ID: <200606190915.50962.jhb@freebsd.org> In-Reply-To: <200606170147.aa09815@nowhere.iedowse.com> References: <200606170147.aa09815@nowhere.iedowse.com>
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On Friday 16 June 2006 20:47, Ian Dowse wrote: > In message <200606161457.23420.jhb@freebsd.org>, John Baldwin writes: > >But unloadentry() would never unload such a module because fp->file > >is NULL. unloadentry() would only call clearentry() and then=20 > >linker_file_unload() on an explicitly loaded firmware module. >=20 > - driver calls firmware_get, firmware image loaded and fp->file set to n= on-NULL > - manually kldload some_module_that_depends_on_firmware_image > - driver calls firmware_put, unloadentry called and sets fp->file =3D NU= LL >=20 > If at this point the entry was cleared then all future calls to > firmware_get would fail even though the module is still available, > referenced and loaded. >=20 > I'm not saying that these cases are particularly important or that > there aren't bugs in the current code; just that mixing up the > layers doesn't help ;-) In practice no modules depend on firmware modules. :) I think we should take the approach of not clearing fp->file in unloadentry() however. That would result in correct behavior in every case I can think of (or as close to correct as you can get). In the above case the linker_file_unload() would have fail leaving the firmware module around. If you later kldunload'ed the other module, the firmware module would still be around and if a driver did another firmware_get/put sequence then the module would finally be unloaded on the second firmware_put(). However, that case will be much more rare than the current standalone firmware modules which can get into a funk where they can never be unloaded since the firmware(9) code would have leaked a reference (since it cleared fp->file just assuming that linker_file_unload() will work, but it might fail) and the user can't use kldunload to unload it even though the firmware isn't in use. =2D-=20 John Baldwin <jhb@FreeBSD.org> =A0<>< =A0http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" =A0=3D =A0http://www.FreeBSD.org
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