On Tue, Apr 11, 2017 at 1:24 AM, John Baldwin <j...@freebsd.org> wrote:
> On Monday, April 10, 2017 04:26:03 PM Patrick Kelsey wrote: > > On Mon, Apr 10, 2017 at 1:43 PM, John Baldwin <j...@freebsd.org> wrote: > > > > > On Monday, April 10, 2017 01:23:04 PM Jung-uk Kim wrote: > > > > On 04/08/2017 22:00, Patrick Kelsey wrote: > > > > > Author: pkelsey > > > > > Date: Sun Apr 9 02:00:03 2017 > > > > > New Revision: 316648 > > > > > URL: https://svnweb.freebsd.org/changeset/base/316648 > > > > > > > > > > Log: > > > > > Corrected misspelled versions of rendezvous. > > > > > > > > > > The MFC will include a compat definition of > > > smp_no_rendevous_barrier() > > > > > that calls smp_no_rendezvous_barrier(). > > > > > > > > > > Reviewed by: gnn, kib > > > > > MFC after: 1 week > > > > > Differential Revision: https://reviews.freebsd.org/D10313 > > > > ... > > > > > > > > We knew about the problem but we didn't fix it because it breaks KPI. > > > > For example, sysutils/virtualbox-ose-kmod. If you really want to MFC > > > > this change, you have to implement shims. > > > > > > Also, the function isn't actually called, but is only used in > comparisons > > > in smp_rendezvous_action(). To do a compat shim you will need to > either > > > change these comparisons to compare against both function pointers or > > > define the alternate symbol as an alias of the existing function. That > > > only helps the KBI though. For the KPI would just use a #define to > point > > > to the new name. > > > > > > > That's a good point about the comparisons in smp_rendezvous_action() - > if I > > had managed to miss that detail all the way through the compat shim > > implementation, it would have littered pointless empty function > invocations > > and atomic increments into all the uses of smp_rendezvous() that used > > smp_no_rendezvous_barrier for at least one of the stages. > > > > I don't think we have an established place to define machine-independent > > symbol aliases. Approaching that through linker scripts would require > > spamming a PROVIDE() statement into each of the arch-specific scripts. > > Since this is a function, I think a better way than the symbol alias + > > #define approach would be to just define a function pointer called > > smp_no_rendevous_barrier that gets statically initialized to > > smp_no_rendezvous_barrier. In that case, the extern decl takes care of > the > > KPI, the corresponding symbol definition takes care of the KBI, and it > has > > a minimal, MI, code footprint. > > I was thinking something along the lines of __weak_reference() from > sys/cdefs.h. Actually, maybe > __strong_reference(smp_no_rendezvous, smp_no_rendevous_barrier) > would be sufficient? > > __strong_reference() is it. > > Either that, or I relax the goal of purging it entirely and put the > compat > > shim in current also to sidestep the port-patching issue. > > Well, I'd like to not have it live around forever, but we could add the > compat shim to HEAD in the short term (also makes MFC slightly simpler as > you just group the two commits together when you MFC). Once the port is > patched with the updated FreeBSD_version we can remove the shim from HEAD. > > So far it doesn't look like patching ports will be much of an issue. I extracted sources for all ports that contained INSTALL_KLD in their Makefile and grepped them for smp_no_rendevous - the only ports turned up that way are emulators/virtualbox-ose-additions and emulators/virtualbox-ose-kmod. One set of patches will serve both, and I've sent them off to the maintainers. -Patrick _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
