[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCHv11 1/4] gnttab: per-active entry locking
>>> On 05.06.15 at 15:41, <david.vrabel@xxxxxxxxxx> wrote: > On 05/06/15 14:32, Jan Beulich wrote: >>>>> On 02.06.15 at 18:26, <david.vrabel@xxxxxxxxxx> wrote: >>> @@ -546,13 +567,19 @@ static void mapcount( >>> >>> *wrc = *rdc = 0; >>> >>> + /* >>> + * Must have the remote domain's grant table lock while counting >>> + * its active entries. >>> + */ >>> + ASSERT(spin_is_locked(&rd->grant_table->lock)); >>> + >>> for ( handle = 0; handle < lgt->maptrack_limit; handle++ ) >> >> The comment and the use of lgt->maptrack_limit contradict the >> documentation you add in patch 2, and it indeed is unclear why >> at this point the local domain's lock (its maptrack lock starting >> with patch 2) doesn't also need to be held. > > Maybe it's a a bit subtle, but holding the local (write) lock means no > new mappings can be created and thus lgt->maptrack_limit cannot change. > > Should I add > > ASSERT(spin_is_locked(&lgt->lock)); > > here as well? Yes, that's what I was basically asking about. And the subtlety should probably be spelled out in a comment. Jan _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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