Date: Mon, 19 Jun 2006 14:27:26 -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: <200606191427.27395.jhb@freebsd.org> In-Reply-To: <200606191924.aa78290@nowhere.iedowse.com> References: <200606191924.aa78290@nowhere.iedowse.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On Monday 19 June 2006 14:24, Ian Dowse wrote:
> In message <200606190915.50962.jhb@freebsd.org>, John Baldwin writes:
> >On Friday 16 June 2006 20:47, Ian Dowse wrote:
> >> - driver calls firmware_get, firmware image loaded and fp->file set to
non-NULL
> >> - manually kldload some_module_that_depends_on_firmware_image
> >> - driver calls firmware_put, unloadentry called and sets fp->file = NULL
> >
> >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.
>
> How about the following patch? In the above case linker_file_unload()
> would actually succeed because the linker file reference count is
> just dropping from 2 to 1, so we'd get a negative reference count
> later if we kept fp->file non-NULL after it returns.
>
> Ian
>
> Index: subr_firmware.c
> ===================================================================
> RCS file: /home/ncvs/src/sys/kern/subr_firmware.c,v
> retrieving revision 1.2
> diff -u -r1.2 subr_firmware.c
> --- subr_firmware.c 10 Jun 2006 17:04:07 -0000 1.2
> +++ subr_firmware.c 19 Jun 2006 18:15:21 -0000
> @@ -206,7 +206,7 @@
> {
> struct firmware *fp;
> linker_file_t file;
> - int i;
> + int i, err;
>
> mtx_lock(&firmware_mtx);
> for (;;) {
> @@ -226,9 +226,18 @@
> fp->file = NULL;
> mtx_unlock(&firmware_mtx);
>
> - linker_file_unload(file, LINKER_UNLOAD_NORMAL);
> -
> + err = linker_file_unload(file, LINKER_UNLOAD_NORMAL);
> mtx_lock(&firmware_mtx);
> + if (err) {
> + /*
> + * If linker_file_unload() failed then we still hold
> + * a reference on the module so it should not be
> + * possible for it to go away or be re-registered.
> + */
> + KASSERT(fp->file == NULL,
> + ("firmware entry reused while referenced!"));
> + fp->file = file;
> + }
> }
> mtx_unlock(&firmware_mtx);
> }
>
Ok.
--
John Baldwin
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200606191427.27395.jhb>