| Message ID | 159500760539.383731.10928308889360009122.stgit@bahia.lan (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [for-5.2] spapr: Simplify error handling in spapr_phb_realize() | expand |
Greg Kurz <groug@kaod.org> writes: > The spapr_phb_realize() function has a local_err variable which > is used to: > > 1) check failures of spapr_irq_findone() and spapr_irq_claim() > > 2) prepend extra information to the error message > > Recent work from Markus Armbruster highlighted we get better > code when testing the return value of a function, rather than > setting up all the local_err boiler plate. For similar reasons, > it is now preferred to use ERRP_GUARD() and error_prepend() > rather than error_propagate_prepend(). > > Since spapr_irq_findone() and spapr_irq_claim() return negative > values in case of failure, do both changes. > > This is just cleanup, no functional impact. > > Signed-off-by: Greg Kurz <groug@kaod.org> > --- > > Since we add ERRP_GUARD(), we could theoretically check *errp > rather than the return value, and thus avoid the uint32_t to > int32_t change but I personally find it clearer the other way. > --- > hw/ppc/spapr_pci.c | 16 +++++++--------- > 1 file changed, 7 insertions(+), 9 deletions(-) > > diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c > index 21681215d405..b1ce51327db4 100644 > --- a/hw/ppc/spapr_pci.c > +++ b/hw/ppc/spapr_pci.c > @@ -1796,6 +1796,7 @@ static void spapr_phb_destroy_msi(gpointer opaque) > > static void spapr_phb_realize(DeviceState *dev, Error **errp) > { > + ERRP_GUARD(); > /* We don't use SPAPR_MACHINE() in order to exit gracefully if the user > * tries to add a sPAPR PHB to a non-pseries machine. > */ > @@ -1813,7 +1814,6 @@ static void spapr_phb_realize(DeviceState *dev, Error **errp) > uint64_t msi_window_size = 4096; > SpaprTceTable *tcet; > const unsigned windows_supported = spapr_phb_windows_supported(sphb); > - Error *local_err = NULL; > > if (!spapr) { > error_setg(errp, TYPE_SPAPR_PCI_HOST_BRIDGE " needs a pseries machine"); > @@ -1964,13 +1964,12 @@ static void spapr_phb_realize(DeviceState *dev, Error **errp) > > /* Initialize the LSI table */ > for (i = 0; i < PCI_NUM_PINS; i++) { > - uint32_t irq = SPAPR_IRQ_PCI_LSI + sphb->index * PCI_NUM_PINS + i; > + int32_t irq = SPAPR_IRQ_PCI_LSI + sphb->index * PCI_NUM_PINS + i; (1) > > if (smc->legacy_irq_allocation) { > - irq = spapr_irq_findone(spapr, &local_err); > - if (local_err) { > - error_propagate_prepend(errp, local_err, > - "can't allocate LSIs: "); > + irq = spapr_irq_findone(spapr, errp); (2) > + if (irq < 0) { > + error_prepend(errp, "can't allocate LSIs: "); > /* > * Older machines will never support PHB hotplug, ie, this is an > * init only path and QEMU will terminate. No need to rollback. > @@ -1979,9 +1978,8 @@ static void spapr_phb_realize(DeviceState *dev, Error **errp) > } > } > > - spapr_irq_claim(spapr, irq, true, &local_err); > - if (local_err) { > - error_propagate_prepend(errp, local_err, "can't allocate LSIs: "); > + if (spapr_irq_claim(spapr, irq, true, errp) < 0) { (3) > + error_prepend(errp, "can't allocate LSIs: "); > goto unrealize; > } sphb->lsi_table[i].irq = irq; (4) } The error propagation elimination looks good to me, but I wonder whether int32_t is the best choice for @irq. Before the patch: (1) The initialization converts unsigned (I think) to uint32_t. (2) Converts from int (value of spapr_irq_findone()) to uint32_t. (3) spapr_irq_claim() takes int, we convert back to int. (4) The assignment does not convert. After the patch: (1) The initialization converts unsigned (I think) to int32_t. (2) Converts from int (value of spapr_irq_findone()) to int32_t. (3) spapr_irq_claim() takes int, we convert back to int. (4) Converts from int32_t to uint32_t I assume the conversions are all safe before and after the patch (spapr_irq_claim() asserts @irq is between 0x1000 and 0x1000 + small change). Still, too many conversions for my taste. What about making irq plain int? Then: (1) The initialization converts unsigned (I think) to int. (2) Does not convert. (3) Does not convert. (4) Converts from int to uint32_t. Feels neater to me. Regardless: Reviewed-by: Markus Armbruster <armbru@redhat.com>
On Mon, Jul 20, 2020 at 11:29:06AM +0200, Markus Armbruster wrote: > Greg Kurz <groug@kaod.org> writes: > > > The spapr_phb_realize() function has a local_err variable which > > is used to: > > > > 1) check failures of spapr_irq_findone() and spapr_irq_claim() > > > > 2) prepend extra information to the error message > > > > Recent work from Markus Armbruster highlighted we get better > > code when testing the return value of a function, rather than > > setting up all the local_err boiler plate. For similar reasons, > > it is now preferred to use ERRP_GUARD() and error_prepend() > > rather than error_propagate_prepend(). > > > > Since spapr_irq_findone() and spapr_irq_claim() return negative > > values in case of failure, do both changes. > > > > This is just cleanup, no functional impact. > > > > Signed-off-by: Greg Kurz <groug@kaod.org> > > --- > > > > Since we add ERRP_GUARD(), we could theoretically check *errp > > rather than the return value, and thus avoid the uint32_t to > > int32_t change but I personally find it clearer the other way. > > --- > > hw/ppc/spapr_pci.c | 16 +++++++--------- > > 1 file changed, 7 insertions(+), 9 deletions(-) > > > > diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c > > index 21681215d405..b1ce51327db4 100644 > > --- a/hw/ppc/spapr_pci.c > > +++ b/hw/ppc/spapr_pci.c > > @@ -1796,6 +1796,7 @@ static void spapr_phb_destroy_msi(gpointer opaque) > > > > static void spapr_phb_realize(DeviceState *dev, Error **errp) > > { > > + ERRP_GUARD(); > > /* We don't use SPAPR_MACHINE() in order to exit gracefully if the user > > * tries to add a sPAPR PHB to a non-pseries machine. > > */ > > @@ -1813,7 +1814,6 @@ static void spapr_phb_realize(DeviceState *dev, Error **errp) > > uint64_t msi_window_size = 4096; > > SpaprTceTable *tcet; > > const unsigned windows_supported = spapr_phb_windows_supported(sphb); > > - Error *local_err = NULL; > > > > if (!spapr) { > > error_setg(errp, TYPE_SPAPR_PCI_HOST_BRIDGE " needs a pseries machine"); > > @@ -1964,13 +1964,12 @@ static void spapr_phb_realize(DeviceState *dev, Error **errp) > > > > /* Initialize the LSI table */ > > for (i = 0; i < PCI_NUM_PINS; i++) { > > - uint32_t irq = SPAPR_IRQ_PCI_LSI + sphb->index * PCI_NUM_PINS + i; > > + int32_t irq = SPAPR_IRQ_PCI_LSI + sphb->index * PCI_NUM_PINS + i; > > (1) > > > > > if (smc->legacy_irq_allocation) { > > - irq = spapr_irq_findone(spapr, &local_err); > > - if (local_err) { > > - error_propagate_prepend(errp, local_err, > > - "can't allocate LSIs: "); > > + irq = spapr_irq_findone(spapr, errp); > > (2) > > > + if (irq < 0) { > > + error_prepend(errp, "can't allocate LSIs: "); > > /* > > * Older machines will never support PHB hotplug, ie, this is an > > * init only path and QEMU will terminate. No need to rollback. > > @@ -1979,9 +1978,8 @@ static void spapr_phb_realize(DeviceState *dev, Error **errp) > > } > > } > > > > - spapr_irq_claim(spapr, irq, true, &local_err); > > - if (local_err) { > > - error_propagate_prepend(errp, local_err, "can't allocate LSIs: "); > > + if (spapr_irq_claim(spapr, irq, true, errp) < 0) { > > (3) > > > + error_prepend(errp, "can't allocate LSIs: "); > > goto unrealize; > > } > > sphb->lsi_table[i].irq = irq; > > (4) > > } > > The error propagation elimination looks good to me, but I wonder whether > int32_t is the best choice for @irq. > > Before the patch: > > (1) The initialization converts unsigned (I think) to uint32_t. > > (2) Converts from int (value of spapr_irq_findone()) to uint32_t. > > (3) spapr_irq_claim() takes int, we convert back to int. > > (4) The assignment does not convert. > > After the patch: > > (1) The initialization converts unsigned (I think) to int32_t. > > (2) Converts from int (value of spapr_irq_findone()) to int32_t. > > (3) spapr_irq_claim() takes int, we convert back to int. > > (4) Converts from int32_t to uint32_t > > I assume the conversions are all safe before and after the patch > (spapr_irq_claim() asserts @irq is between 0x1000 and 0x1000 + small > change). Still, too many conversions for my taste. What about making > irq plain int? Then: > > (1) The initialization converts unsigned (I think) to int. > > (2) Does not convert. > > (3) Does not convert. > > (4) Converts from int to uint32_t. > > Feels neater to me. Sounds like a good idea. Greg, care to post a followup patch? > > Regardless: > Reviewed-by: Markus Armbruster <armbru@redhat.com> >
diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c index 21681215d405..b1ce51327db4 100644 --- a/hw/ppc/spapr_pci.c +++ b/hw/ppc/spapr_pci.c @@ -1796,6 +1796,7 @@ static void spapr_phb_destroy_msi(gpointer opaque) static void spapr_phb_realize(DeviceState *dev, Error **errp) { + ERRP_GUARD(); /* We don't use SPAPR_MACHINE() in order to exit gracefully if the user * tries to add a sPAPR PHB to a non-pseries machine. */ @@ -1813,7 +1814,6 @@ static void spapr_phb_realize(DeviceState *dev, Error **errp) uint64_t msi_window_size = 4096; SpaprTceTable *tcet; const unsigned windows_supported = spapr_phb_windows_supported(sphb); - Error *local_err = NULL; if (!spapr) { error_setg(errp, TYPE_SPAPR_PCI_HOST_BRIDGE " needs a pseries machine"); @@ -1964,13 +1964,12 @@ static void spapr_phb_realize(DeviceState *dev, Error **errp) /* Initialize the LSI table */ for (i = 0; i < PCI_NUM_PINS; i++) { - uint32_t irq = SPAPR_IRQ_PCI_LSI + sphb->index * PCI_NUM_PINS + i; + int32_t irq = SPAPR_IRQ_PCI_LSI + sphb->index * PCI_NUM_PINS + i; if (smc->legacy_irq_allocation) { - irq = spapr_irq_findone(spapr, &local_err); - if (local_err) { - error_propagate_prepend(errp, local_err, - "can't allocate LSIs: "); + irq = spapr_irq_findone(spapr, errp); + if (irq < 0) { + error_prepend(errp, "can't allocate LSIs: "); /* * Older machines will never support PHB hotplug, ie, this is an * init only path and QEMU will terminate. No need to rollback. @@ -1979,9 +1978,8 @@ static void spapr_phb_realize(DeviceState *dev, Error **errp) } } - spapr_irq_claim(spapr, irq, true, &local_err); - if (local_err) { - error_propagate_prepend(errp, local_err, "can't allocate LSIs: "); + if (spapr_irq_claim(spapr, irq, true, errp) < 0) { + error_prepend(errp, "can't allocate LSIs: "); goto unrealize; }
The spapr_phb_realize() function has a local_err variable which is used to: 1) check failures of spapr_irq_findone() and spapr_irq_claim() 2) prepend extra information to the error message Recent work from Markus Armbruster highlighted we get better code when testing the return value of a function, rather than setting up all the local_err boiler plate. For similar reasons, it is now preferred to use ERRP_GUARD() and error_prepend() rather than error_propagate_prepend(). Since spapr_irq_findone() and spapr_irq_claim() return negative values in case of failure, do both changes. This is just cleanup, no functional impact. Signed-off-by: Greg Kurz <groug@kaod.org> --- Since we add ERRP_GUARD(), we could theoretically check *errp rather than the return value, and thus avoid the uint32_t to int32_t change but I personally find it clearer the other way. --- hw/ppc/spapr_pci.c | 16 +++++++--------- 1 file changed, 7 insertions(+), 9 deletions(-)