On Mon, Jan 18, 2016 at 11:21:08AM +0100, Markus Armbruster wrote:
> Thomas Huth <th...@redhat.com> writes:
>
> > On 18.01.2016 05:24, David Gibson wrote:
> >> The spapr_alloc_htab() and spapr_reset_htab() functions currently handle
> >> all errors with error_setg(&error_abort, ...).
> >>
> >> But really, the callers are really better placed to decide on the error
> >> handling. So, instead make the functions use the error propagation
> >> infrastructure.
> >>
> >> In the callers we change to &error_fatal instead of &error_abort, since
> >> this can be triggered by a bad configuration or kernel error rather than
> >> indicating a programming error in qemu.
> >>
> >> While we're at it improve the messages themselves a bit, and clean up the
> >> indentation a little.
> >>
> >> Signed-off-by: David Gibson <da...@gibson.dropbear.id.au>
> >> ---
> >> hw/ppc/spapr.c | 24 ++++++++++++++++--------
> >> 1 file changed, 16 insertions(+), 8 deletions(-)
> >>
> >> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> >> index b7fd09a..d28e349 100644
> >> --- a/hw/ppc/spapr.c
> >> +++ b/hw/ppc/spapr.c
> >> @@ -1016,7 +1016,7 @@ static void emulate_spapr_hypercall(PowerPCCPU *cpu)
> >> #define CLEAN_HPTE(_hpte) ((*(uint64_t *)(_hpte)) &=
> >> tswap64(~HPTE64_V_HPTE_DIRTY))
> >> #define DIRTY_HPTE(_hpte) ((*(uint64_t *)(_hpte)) |=
> >> tswap64(HPTE64_V_HPTE_DIRTY))
> >>
> >> -static void spapr_alloc_htab(sPAPRMachineState *spapr)
> >> +static void spapr_alloc_htab(sPAPRMachineState *spapr, Error **errp)
> >> {
> >> long shift;
> >> int index;
> >> @@ -1031,7 +1031,8 @@ static void spapr_alloc_htab(sPAPRMachineState
> >> *spapr)
> >> * For HV KVM, host kernel will return -ENOMEM when requested
> >> * HTAB size can't be allocated.
> >> */
> >> - error_setg(&error_abort, "Failed to allocate HTAB of requested
> >> size, try with smaller maxmem");
> >> + error_setg_errno(errp, -shift,
> >> + "Error allocating KVM hash page table, try
> >> smaller maxmem");
> >> } else if (shift > 0) {
> >> /*
> >> * Kernel handles htab, we don't need to allocate one
> >> @@ -1040,7 +1041,10 @@ static void spapr_alloc_htab(sPAPRMachineState
> >> *spapr)
> >> * but we don't allow booting of such guests.
> >> */
> >> if (shift != spapr->htab_shift) {
> >> - error_setg(&error_abort, "Failed to allocate HTAB of
> >> requested size, try with smaller maxmem");
> >> + error_setg(errp,
> >> + "Small allocation for KVM hash page table (%ld < %"
> >> + PRIu32 "), try smaller maxmem",
> >> + shift, spapr->htab_shift);
> >
> > Maybe you should add an "return" statement here - theoretically you do
> > not want to continue with "kvmppc_kern_htab = true" in case of errors.
> > (practically this does not happen because errp = error_fatal, but in
> > case the caller gets changed, this might introduce subtle errors otherwise)
>
> Good point.
>
> With abort() / exit(), we don't have to worry about recovery. In
> particular, we don't have to revert half-done changes.
>
> Conversions away from abort() / exit() need to consider error recovery.
> We have to make sure the function leaves things in a sane state on
> error. This normally means taking an early return, and often means
> reverting some state changes.
That's true, but Thomas is mistaken about what error recovery is
needed here.
However, I'm going to drop this patch from the series anyway - I've
realised I need to rework the htab allocation substantially for other
reasons, so it would be better to not have that conflict with this
series.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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