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Re: [Qemu-devel] [Qemu-ppc] [PATCH v2] spapr: fix memory hotplug error p
From: |
Greg Kurz |
Subject: |
Re: [Qemu-devel] [Qemu-ppc] [PATCH v2] spapr: fix memory hotplug error path |
Date: |
Tue, 4 Jul 2017 09:42:52 +0200 |
On Mon, 3 Jul 2017 14:03:07 -0300
Daniel Henrique Barboza <address@hidden> wrote:
> On 07/03/2017 11:54 AM, Greg Kurz wrote:
> > QEMU shouldn't abort if spapr_add_lmbs()->spapr_drc_attach() fails.
> > Let's propagate the error instead, like it is done everywhere else
> > where spapr_drc_attach() is called.
> >
> > Signed-off-by: Greg Kurz <address@hidden>
> > ---
> > Changes in v2: - added rollback code
> > ---
> > hw/ppc/spapr.c | 26 ++++++++++++++++++++++----
> > 1 file changed, 22 insertions(+), 4 deletions(-)
> >
> > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> > index 70b3fd374e2b..ba8f57a5a054 100644
> > --- a/hw/ppc/spapr.c
> > +++ b/hw/ppc/spapr.c
> > @@ -2601,6 +2601,7 @@ static void spapr_add_lmbs(DeviceState *dev, uint64_t
> > addr_start, uint64_t size,
> > int i, fdt_offset, fdt_size;
> > void *fdt;
> > uint64_t addr = addr_start;
> > + Error *local_err = NULL;
> >
> > for (i = 0; i < nr_lmbs; i++) {
> > drc = spapr_drc_by_id(TYPE_SPAPR_DRC_LMB,
> > @@ -2611,7 +2612,18 @@ static void spapr_add_lmbs(DeviceState *dev,
> > uint64_t addr_start, uint64_t size,
> > fdt_offset = spapr_populate_memory_node(fdt, node, addr,
> > SPAPR_MEMORY_BLOCK_SIZE);
> >
> > - spapr_drc_attach(drc, dev, fdt, fdt_offset, errp);
> > + spapr_drc_attach(drc, dev, fdt, fdt_offset, &local_err);
> > + if (local_err) {
> > + while (addr > addr_start) {
> > + addr -= SPAPR_MEMORY_BLOCK_SIZE;
> > + drc = spapr_drc_by_id(TYPE_SPAPR_DRC_LMB,
> > + addr / SPAPR_MEMORY_BLOCK_SIZE);
> > + spapr_drc_detach(drc, dev, NULL);
>
> Question: why pass NULL instead of '&local_err' in detach() ?
local_err already contains the error returned by spapr_drc_attach(), it
cannot be used anymore.
> Can we ignore any
> any error that happens in detach() because you're propagating the
> local_err set
> in spapr_drc_attach() already?
>
This is a rollback path: the best we can do is to try to undo the
already attached DRCs...
> ps: I am aware that ATM detach() does not propagate anything to the errp
> being
> passed. I don't think it's wise to write new code based on this
> assumption though.
>
... and indeed detach() cannot fail with the current code base. :)
David was even planning to drop the errp argument in the "spapr:
Refactor spapr_drc_detach()" patch.
Otherwise, maybe pass &error_abort since failing to rollback is
likely to be a bug ?
Cheers,
--
Greg
>
> Thanks,
>
>
> Daniel
>
> > + }
> > + g_free(fdt);
> > + error_propagate(errp, local_err);
> > + return;
> > + }
> > addr += SPAPR_MEMORY_BLOCK_SIZE;
> > }
> > /* send hotplug notification to the
> > @@ -2651,14 +2663,20 @@ static void spapr_memory_plug(HotplugHandler
> > *hotplug_dev, DeviceState *dev,
> > addr = object_property_get_uint(OBJECT(dimm),
> > PC_DIMM_ADDR_PROP, &local_err);
> > if (local_err) {
> > - pc_dimm_memory_unplug(dev, &ms->hotplug_memory, mr);
> > - goto out;
> > + goto out_unplug;
> > }
> >
> > spapr_add_lmbs(dev, addr, size, node,
> > spapr_ovec_test(ms->ov5_cas, OV5_HP_EVT),
> > - &error_abort);
> > + &local_err);
> > + if (local_err) {
> > + goto out_unplug;
> > + }
> > +
> > + return;
> >
> > +out_unplug:
> > + pc_dimm_memory_unplug(dev, &ms->hotplug_memory, mr);
> > out:
> > error_propagate(errp, local_err);
> > }
> >
> >
>
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