Re: [Qemu-devel] [PATCH 06/11] pseries: Improve error handling in find_unknown_sysbus_device()
On Fri, Dec 11, 2015 at 10:49:40AM +0100, Thomas Huth wrote:
> On 11/12/15 01:11, David Gibson wrote:
> > Use error_setg() to return an error instead of using an explicit exit().
> >
> > Signed-off-by: David Gibson
> > ---
> > hw/ppc/spapr.c | 9 +
> > 1 file changed, 5 insertions(+), 4 deletions(-)
> >
> > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> > index 0ff09b9..fd16db4 100644
> > --- a/hw/ppc/spapr.c
> > +++ b/hw/ppc/spapr.c
> > @@ -1107,6 +1107,7 @@ static void spapr_reset_htab(sPAPRMachineState
> > *spapr, Error **errp)
> >
> > static int find_unknown_sysbus_device(SysBusDevice *sbdev, void *opaque)
> > {
> > +Error **errp = opaque;
> > bool matched = false;
> >
> > if (object_dynamic_cast(OBJECT(sbdev), TYPE_SPAPR_PCI_HOST_BRIDGE)) {
> > @@ -1114,9 +1115,9 @@ static int find_unknown_sysbus_device(SysBusDevice
> > *sbdev, void *opaque)
> > }
> >
> > if (!matched) {
> > -error_report("Device %s is not supported by this machine yet.",
> > - qdev_fw_name(DEVICE(sbdev)));
> > -exit(1);
> > +error_setg(errp,
> > + "Device %s is not supported by this machine yet",
> > + qdev_fw_name(DEVICE(sbdev)));
> > }
> >
> > return 0;
> > @@ -1151,7 +1152,7 @@ static void ppc_spapr_reset(void)
> > uint32_t rtas_limit;
> >
> > /* Check for unknown sysbus devices */
> > -foreach_dynamic_sysbus_device(find_unknown_sysbus_device, NULL);
> > +foreach_dynamic_sysbus_device(find_unknown_sysbus_device,
> > &error_abort);
> >
> > /* Reset the hash table & recalc the RMA */
> > spapr_reset_htab(spapr, &error_abort);
>
> Can this error be triggered by the user (by plugging certain devices or
> so)? If so, I'm not sure whether error_abort is the right thing to use
> here ... it's always ugly if the user can trigger an abort directly.
> Maybe error_fatal would be better instead?
Hm. So, yes, I think it can be triggered by the user. I used
&error_abort on the grounds that this is during reset - after the
initial setup phase.
Markus, do you have an opinion on what the right handling here is?
--
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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Re: [Qemu-devel] [PATCH 06/11] pseries: Improve error handling in find_unknown_sysbus_device()
On Fri, Dec 11, 2015 at 08:15:39AM -0700, Eric Blake wrote:
> On 12/10/2015 05:11 PM, David Gibson wrote:
> > Use error_setg() to return an error instead of using an explicit exit().
> >
> > Signed-off-by: David Gibson
> > ---
> > hw/ppc/spapr.c | 9 +
> > 1 file changed, 5 insertions(+), 4 deletions(-)
> >
>
> > +++ b/hw/ppc/spapr.c
> > @@ -1107,6 +1107,7 @@ static void spapr_reset_htab(sPAPRMachineState
> > *spapr, Error **errp)
> >
> > static int find_unknown_sysbus_device(SysBusDevice *sbdev, void *opaque)
> > {
>
> > if (!matched) {
> > -error_report("Device %s is not supported by this machine yet.",
> > - qdev_fw_name(DEVICE(sbdev)));
> > -exit(1);
> > +error_setg(errp,
> > + "Device %s is not supported by this machine yet",
> > + qdev_fw_name(DEVICE(sbdev)));
> > }
> >
> > return 0;
>
> It looks like find_unknown_sysbus_device is designed to be called in a
> loop, and that returning 0 lets the loop continue.
>
> > @@ -1151,7 +1152,7 @@ static void ppc_spapr_reset(void)
> > uint32_t rtas_limit;
> >
> > /* Check for unknown sysbus devices */
> > -foreach_dynamic_sysbus_device(find_unknown_sysbus_device, NULL);
> > +foreach_dynamic_sysbus_device(find_unknown_sysbus_device,
> > &error_abort);
>
> If a caller passes something other than &error_abort as the opaque, AND
> the error condition occurs more than once in the loop iteration, then
> you really need to change find_unknown_sysbus_device() to return
> non-zero after raising error on the first failure, so that the loop
> doesn't continue on to a second pass and attempt an error_setg() onto an
> already-set error.
Ah, good catch. I'll correct in the next spin.
> Of course, since _this_ patch uses &error_abort as the only client, the
> loop will never continue after the first failure, but it's more robust
> to be clean without having to audit the callers.
>
--
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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Re: [Qemu-devel] [PATCH 06/11] pseries: Improve error handling in find_unknown_sysbus_device()
On 12/10/2015 05:11 PM, David Gibson wrote:
> Use error_setg() to return an error instead of using an explicit exit().
>
> Signed-off-by: David Gibson
> ---
> hw/ppc/spapr.c | 9 +
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> +++ b/hw/ppc/spapr.c
> @@ -1107,6 +1107,7 @@ static void spapr_reset_htab(sPAPRMachineState *spapr,
> Error **errp)
>
> static int find_unknown_sysbus_device(SysBusDevice *sbdev, void *opaque)
> {
> if (!matched) {
> -error_report("Device %s is not supported by this machine yet.",
> - qdev_fw_name(DEVICE(sbdev)));
> -exit(1);
> +error_setg(errp,
> + "Device %s is not supported by this machine yet",
> + qdev_fw_name(DEVICE(sbdev)));
> }
>
> return 0;
It looks like find_unknown_sysbus_device is designed to be called in a
loop, and that returning 0 lets the loop continue.
> @@ -1151,7 +1152,7 @@ static void ppc_spapr_reset(void)
> uint32_t rtas_limit;
>
> /* Check for unknown sysbus devices */
> -foreach_dynamic_sysbus_device(find_unknown_sysbus_device, NULL);
> +foreach_dynamic_sysbus_device(find_unknown_sysbus_device, &error_abort);
If a caller passes something other than &error_abort as the opaque, AND
the error condition occurs more than once in the loop iteration, then
you really need to change find_unknown_sysbus_device() to return
non-zero after raising error on the first failure, so that the loop
doesn't continue on to a second pass and attempt an error_setg() onto an
already-set error.
Of course, since _this_ patch uses &error_abort as the only client, the
loop will never continue after the first failure, but it's more robust
to be clean without having to audit the callers.
--
Eric Blake eblake redhat com+1-919-301-3266
Libvirt virtualization library http://libvirt.org
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Re: [Qemu-devel] [PATCH 06/11] pseries: Improve error handling in find_unknown_sysbus_device()
On 11/12/15 01:11, David Gibson wrote:
> Use error_setg() to return an error instead of using an explicit exit().
>
> Signed-off-by: David Gibson
> ---
> hw/ppc/spapr.c | 9 +
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 0ff09b9..fd16db4 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -1107,6 +1107,7 @@ static void spapr_reset_htab(sPAPRMachineState *spapr,
> Error **errp)
>
> static int find_unknown_sysbus_device(SysBusDevice *sbdev, void *opaque)
> {
> +Error **errp = opaque;
> bool matched = false;
>
> if (object_dynamic_cast(OBJECT(sbdev), TYPE_SPAPR_PCI_HOST_BRIDGE)) {
> @@ -1114,9 +1115,9 @@ static int find_unknown_sysbus_device(SysBusDevice
> *sbdev, void *opaque)
> }
>
> if (!matched) {
> -error_report("Device %s is not supported by this machine yet.",
> - qdev_fw_name(DEVICE(sbdev)));
> -exit(1);
> +error_setg(errp,
> + "Device %s is not supported by this machine yet",
> + qdev_fw_name(DEVICE(sbdev)));
> }
>
> return 0;
> @@ -1151,7 +1152,7 @@ static void ppc_spapr_reset(void)
> uint32_t rtas_limit;
>
> /* Check for unknown sysbus devices */
> -foreach_dynamic_sysbus_device(find_unknown_sysbus_device, NULL);
> +foreach_dynamic_sysbus_device(find_unknown_sysbus_device, &error_abort);
>
> /* Reset the hash table & recalc the RMA */
> spapr_reset_htab(spapr, &error_abort);
Can this error be triggered by the user (by plugging certain devices or
so)? If so, I'm not sure whether error_abort is the right thing to use
here ... it's always ugly if the user can trigger an abort directly.
Maybe error_fatal would be better instead?
Thomas
