Re: [PATCH v2 17/33] xive: Improve irq claim/free path

[David Gibson]

On Fri, Sep 27, 2019 at 10:40:14AM +0200, Greg Kurz wrote:
> On Fri, 27 Sep 2019 15:50:12 +1000
> David Gibson <address@hidden> wrote:
> 
> > spapr_xive_irq_claim() returns a bool to indicate if it succeeded.
> > But most of the callers and one callee use int return values and/or an
> > Error * with more information instead.  In any case, ints are a more
> > common idiom for success/failure states than bools (one never knows
> > what sense they'll be in).
> > 
> > So instead change to an int return value to indicate presence of error
> > + an Error * to describe the details through that call chain.
> > 
> > It also didn't actually check if the irq was already claimed, which is
> > one of the primary purposes of the claim path, so do that.
> > 
> > spapr_xive_irq_free() also returned a bool... which no callers checked
> > and was always true, so just drop it.
> > 
> > Signed-off-by: David Gibson <address@hidden>
> > Reviewed-by: Cédric Le Goater <address@hidden>
> > ---
> >  hw/intc/spapr_xive.c        | 20 +++++++++-----------
> >  hw/intc/spapr_xive_kvm.c    |  8 ++++----
> >  hw/ppc/spapr_irq.c          | 14 ++++++++------
> >  include/hw/ppc/spapr_xive.h |  4 ++--
> >  include/hw/ppc/xive.h       |  2 +-
> >  5 files changed, 24 insertions(+), 24 deletions(-)
> > 
> > diff --git a/hw/intc/spapr_xive.c b/hw/intc/spapr_xive.c
> > index 47b5ec0b56..04879abf2e 100644
> > --- a/hw/intc/spapr_xive.c
> > +++ b/hw/intc/spapr_xive.c
> > @@ -528,12 +528,17 @@ static void spapr_xive_register_types(void)
> >  
> >  type_init(spapr_xive_register_types)
> >  
> > -bool spapr_xive_irq_claim(SpaprXive *xive, uint32_t lisn, bool lsi)
> > +int spapr_xive_irq_claim(SpaprXive *xive, int lisn, bool lsi, Error **errp)
> >  {
> >      XiveSource *xsrc = &xive->source;
> >  
> >      assert(lisn < xive->nr_irqs);
> >  
> > +    if (xive_eas_is_valid(&xive->eat[lisn])) {
> > +        error_setg(errp, "IRQ %d is not free", lisn);
> > +        return -EBUSY;
> > +    }
> > +
> >      /*
> >       * Set default values when allocating an IRQ number
> >       */
> > @@ -543,24 +548,17 @@ bool spapr_xive_irq_claim(SpaprXive *xive, uint32_t 
> > lisn, bool lsi)
> >      }
> >  
> >      if (kvm_irqchip_in_kernel()) {
> > -        Error *local_err = NULL;
> > -
> > -        kvmppc_xive_source_reset_one(xsrc, lisn, &local_err);
> > -        if (local_err) {
> > -            error_report_err(local_err);
> > -            return false;
> > -        }
> > +        return kvmppc_xive_source_reset_one(xsrc, lisn, errp);
> >      }
> >  
> > -    return true;
> > +    return 0;
> >  }
> >  
> > -bool spapr_xive_irq_free(SpaprXive *xive, uint32_t lisn)
> > +void spapr_xive_irq_free(SpaprXive *xive, int lisn)
> >  {
> >      assert(lisn < xive->nr_irqs);
> >  
> >      xive->eat[lisn].w &= cpu_to_be64(~EAS_VALID);
> > -    return true;
> >  }
> >  
> >  /*
> > diff --git a/hw/intc/spapr_xive_kvm.c b/hw/intc/spapr_xive_kvm.c
> > index 2006f96aec..51b334b676 100644
> > --- a/hw/intc/spapr_xive_kvm.c
> > +++ b/hw/intc/spapr_xive_kvm.c
> > @@ -232,14 +232,14 @@ void kvmppc_xive_sync_source(SpaprXive *xive, 
> > uint32_t lisn, Error **errp)
> >   * only need to inform the KVM XIVE device about their type: LSI or
> >   * MSI.
> >   */
> > -void kvmppc_xive_source_reset_one(XiveSource *xsrc, int srcno, Error 
> > **errp)
> > +int kvmppc_xive_source_reset_one(XiveSource *xsrc, int srcno, Error **errp)
> >  {
> >      SpaprXive *xive = SPAPR_XIVE(xsrc->xive);
> >      uint64_t state = 0;
> >  
> >      /* The KVM XIVE device is not in use */
> >      if (xive->fd == -1) {
> > -        return;
> > +        return -ENODEV;
> >      }
> >  
> >      if (xive_source_irq_is_lsi(xsrc, srcno)) {
> > @@ -249,8 +249,8 @@ void kvmppc_xive_source_reset_one(XiveSource *xsrc, int 
> > srcno, Error **errp)
> >          }
> >      }
> >  
> > -    kvm_device_access(xive->fd, KVM_DEV_XIVE_GRP_SOURCE, srcno, &state,
> > -                      true, errp);
> > +    return kvm_device_access(xive->fd, KVM_DEV_XIVE_GRP_SOURCE, srcno, 
> > &state,
> > +                             true, errp);
> >  }
> >  
> >  static void kvmppc_xive_source_reset(XiveSource *xsrc, Error **errp)
> > diff --git a/hw/ppc/spapr_irq.c b/hw/ppc/spapr_irq.c
> > index da9e80b24e..4951329959 100644
> > --- a/hw/ppc/spapr_irq.c
> > +++ b/hw/ppc/spapr_irq.c
> > @@ -246,7 +246,13 @@ static void spapr_irq_init_xive(SpaprMachineState 
> > *spapr, Error **errp)
> >  
> >      /* Enable the CPU IPIs */
> >      for (i = 0; i < nr_servers; ++i) {
> > -        spapr_xive_irq_claim(spapr->xive, SPAPR_IRQ_IPI + i, false);
> > +        Error *local_err = NULL;
> > +
> > +        spapr_xive_irq_claim(spapr->xive, SPAPR_IRQ_IPI + i, false, 
> > &local_err);
> > +        if (local_err) {
> > +            error_propagate(errp, local_err);
> > +            return;
> > +        }
> 
> Quoting the changelog
> 
> > So instead change to an int return value to indicate presence of error
> > + an Error * to describe the details through that call chain.
> 
> Shouldn't this rather be:
> 
>         if (spapr_xive_irq_claim(spapr->xive, SPAPR_IRQ_IPI + i, false, 
> errp)) {
>             return;
>         }
> 
> ?

Yes, yes it should.  Fixed now.

> 
> With or without that fixed,
> 
> Reviewed-by: Greg Kurz <address@hidden>
> 
> >      }
> >  
> >      spapr_xive_hcall_init(spapr);
> > @@ -255,11 +261,7 @@ static void spapr_irq_init_xive(SpaprMachineState 
> > *spapr, Error **errp)
> >  static int spapr_irq_claim_xive(SpaprMachineState *spapr, int irq, bool 
> > lsi,
> >                                  Error **errp)
> >  {
> > -    if (!spapr_xive_irq_claim(spapr->xive, irq, lsi)) {
> > -        error_setg(errp, "IRQ %d is invalid", irq);
> > -        return -1;
> > -    }
> > -    return 0;
> > +    return spapr_xive_irq_claim(spapr->xive, irq, lsi, errp);
> >  }
> >  
> >  static void spapr_irq_free_xive(SpaprMachineState *spapr, int irq)
> > diff --git a/include/hw/ppc/spapr_xive.h b/include/hw/ppc/spapr_xive.h
> > index bfd40f01d8..0df20a6590 100644
> > --- a/include/hw/ppc/spapr_xive.h
> > +++ b/include/hw/ppc/spapr_xive.h
> > @@ -54,8 +54,8 @@ typedef struct SpaprXive {
> >   */
> >  #define SPAPR_XIVE_BLOCK_ID 0x0
> >  
> > -bool spapr_xive_irq_claim(SpaprXive *xive, uint32_t lisn, bool lsi);
> > -bool spapr_xive_irq_free(SpaprXive *xive, uint32_t lisn);
> > +int spapr_xive_irq_claim(SpaprXive *xive, int lisn, bool lsi, Error 
> > **errp);
> > +void spapr_xive_irq_free(SpaprXive *xive, int lisn);
> >  void spapr_xive_pic_print_info(SpaprXive *xive, Monitor *mon);
> >  int spapr_xive_post_load(SpaprXive *xive, int version_id);
> >  
> > diff --git a/include/hw/ppc/xive.h b/include/hw/ppc/xive.h
> > index 6d38755f84..fd3319bd32 100644
> > --- a/include/hw/ppc/xive.h
> > +++ b/include/hw/ppc/xive.h
> > @@ -425,7 +425,7 @@ static inline uint32_t xive_nvt_cam_line(uint8_t 
> > nvt_blk, uint32_t nvt_idx)
> >   * KVM XIVE device helpers
> >   */
> >  
> > -void kvmppc_xive_source_reset_one(XiveSource *xsrc, int srcno, Error 
> > **errp);
> > +int kvmppc_xive_source_reset_one(XiveSource *xsrc, int srcno, Error 
> > **errp);
> >  void kvmppc_xive_source_set_irq(void *opaque, int srcno, int val);
> >  void kvmppc_xive_cpu_connect(XiveTCTX *tctx, Error **errp);
> >  void kvmppc_xive_cpu_synchronize_state(XiveTCTX *tctx, Error **errp);
> 

-- 
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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