Messages in this thread | | | Date | Tue, 30 Jun 2009 13:30:01 +0300 | From | "Michael S. Tsirkin" <> | Subject | Re: [PATCH v4] slow-work: add (module*)work->ops->owner to fix races with module clients |
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On Tue, Jun 30, 2009 at 10:18:32AM +0100, steve@chygwyn.com wrote: > Hi, > > On Tue, Jun 30, 2009 at 12:07:15PM +0300, Michael S. Tsirkin wrote: > > On Tue, Jun 30, 2009 at 09:43:03AM +0100, Steven Whitehouse wrote: > > > Hi, > > > > > > I'm happy to ACK this, but the race doesn't exist in GFS2's case because > > > we wait for all work related to each GFS2 fs at umount time and the > > > module unload cannot happen until all GFS2 fs are umounted, > > > > > > Steve. > > > > I wonder whether the following holds: > > > > static void gfs2_recover_put_ref(struct slow_work *work) > > { > > struct gfs2_jdesc *jd = container_of(work, struct gfs2_jdesc, jd_work); > > clear_bit(JDF_RECOVERY, &jd->jd_flags); > > smp_mb__after_clear_bit(); > > wake_up_bit(&jd->jd_flags, JDF_RECOVERY); > > > > <- umount can complete here? > > > > } > > > > > > If yes, .text of the module could go away between the point marked by <- > > and return from gfs2_recover_put_ref. > > > > > Well in theory, yes. In reality I don't think it could ever happen
Right. IIUC, that's all Gregory's patch is trying to address: a theoretical race condition.
-- MST
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