[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] Re: [PATCH 5/7] mm: New XENMEM space, XENMAPSPACE_gmfn_range
>>> On 10.11.11 at 18:37, Jean Guyader <jean.guyader@xxxxxxxxxxxxx> wrote: > On 10/11 12:47, Jan Beulich wrote: >> >>> On 10.11.11 at 12:35, Jean Guyader <jean.guyader@xxxxxxxxxxxxx> wrote: >> >@@ -4716,6 +4748,17 @@ long arch_memory_op(int op, XEN_GUEST_HANDLE(void) > arg) >> > } >> > >> > rc = xenmem_add_to_physmap(d, &xatp); >> >+ if ( rc == -EAGAIN ) >> >> if ( rc ) >> >> >+ { >> >+ if ( copy_to_guest(arg, &xatp, 1) ) >> >+ { >> >+ rcu_unlock_domain(d); >> >+ return -EFAULT; >> >+ } >> >> } >> if ( rc == -EAGAIN ) >> >> (with some room for further simplification). Without that (or the minimal >> alternative of copying back just .size or yet some other mechanism), as >> pointed out before, the caller won't have a way to know how far into >> the batch things succeeded. >> > > In xenmem_add_to_physmap I modify xatp in place so when I exit this > function xatp will contain the updated value (new start value in > .gpfn and .idx, how far do I need to go in .size). > > The idea here was to call the copy_to_guest only when we got preempted. > If I copy xatp back to the guest I should get the updated value > in xatp from the copy_from_guest when I'll be called by the continuation. I understand the continuation aspect. But you appear to have not read my comments completely: I'm asking how your caller, in the event of failure, would know how much of the batch was processed successfully. Jan _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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