error: Eliminate error_propagate() with Coccinelle, part 1

When all we do with an Error we receive into a local variable is
propagating to somewhere else, we can just as well receive it there
right away.  Convert

    if (!foo(..., &err)) {
        ...
        error_propagate(errp, err);
        ...
        return ...
    }

to

    if (!foo(..., errp)) {
        ...
        ...
        return ...
    }

where nothing else needs @err.  Coccinelle script:

    @rule1 forall@
    identifier fun, err, errp, lbl;
    expression list args, args2;
    binary operator op;
    constant c1, c2;
    symbol false;
    @@
         if (
    (
    -        fun(args, &err, args2)
    +        fun(args, errp, args2)
    |
    -        !fun(args, &err, args2)
    +        !fun(args, errp, args2)
    |
    -        fun(args, &err, args2) op c1
    +        fun(args, errp, args2) op c1
    )
            )
         {
             ... when != err
                 when != lbl:
                 when strict
    -        error_propagate(errp, err);
             ... when != err
    (
             return;
    |
             return c2;
    |
             return false;
    )
         }

    @rule2 forall@
    identifier fun, err, errp, lbl;
    expression list args, args2;
    expression var;
    binary operator op;
    constant c1, c2;
    symbol false;
    @@
    -    var = fun(args, &err, args2);
    +    var = fun(args, errp, args2);
         ... when != err
         if (
    (
             var
    |
             !var
    |
             var op c1
    )
            )
         {
             ... when != err
                 when != lbl:
                 when strict
    -        error_propagate(errp, err);
             ... when != err
    (
             return;
    |
             return c2;
    |
             return false;
    |
             return var;
    )
         }

    @depends on rule1 || rule2@
    identifier err;
    @@
    -    Error *err = NULL;
         ... when != err

Not exactly elegant, I'm afraid.

The "when != lbl:" is necessary to avoid transforming

         if (fun(args, &err)) {
             goto out
         }
         ...
     out:
         error_propagate(errp, err);

even though other paths to label out still need the error_propagate().
For an actual example, see sclp_realize().

Without the "when strict", Coccinelle transforms vfio_msix_setup(),
incorrectly.  I don't know what exactly "when strict" does, only that
it helps here.

The match of return is narrower than what I want, but I can't figure
out how to express "return where the operand doesn't use @err".  For
an example where it's too narrow, see vfio_intx_enable().

Silently fails to convert hw/arm/armsse.c, because Coccinelle gets
confused by ARMSSE being used both as typedef and function-like macro
there.  Converted manually.

Line breaks tidied up manually.  One nested declaration of @local_err
deleted manually.  Preexisting unwanted blank line dropped in
hw/riscv/sifive_e.c.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200707160613.848843-35-armbru@redhat.com>

6 files changed, 9 insertions, 22 deletions

diff --git a/hw/intc/apic_common.c b/hw/intc/apic_common.c
index 76c3f78e11..dc070343c0 100644
--- a/hw/intc/apic_common.c
+++ b/hw/intc/apic_common.c
@@ -420,7 +420,6 @@ static void apic_common_set_id(Object *obj, Visitor *v, const char *name,
 {
     APICCommonState *s = APIC_COMMON(obj);
     DeviceState *dev = DEVICE(obj);
-    Error *local_err = NULL;
     uint32_t value;
 
     if (dev->realized) {
@@ -428,8 +427,7 @@ static void apic_common_set_id(Object *obj, Visitor *v, const char *name,
         return;
     }
 
-    if (!visit_type_uint32(v, name, &value, &local_err)) {
-        error_propagate(errp, local_err);
+    if (!visit_type_uint32(v, name, &value, errp)) {
         return;
     }
 
diff --git a/hw/intc/armv7m_nvic.c b/hw/intc/armv7m_nvic.c
index 80a915e922..3c4b6e6d70 100644
--- a/hw/intc/armv7m_nvic.c
+++ b/hw/intc/armv7m_nvic.c
@@ -2619,7 +2619,6 @@ static void nvic_systick_trigger(void *opaque, int n, int level)
 static void armv7m_nvic_realize(DeviceState *dev, Error **errp)
 {
     NVICState *s = NVIC(dev);
-    Error *err = NULL;
     int regionlen;
 
     /* The armv7m container object will have set our CPU pointer */
@@ -2640,8 +2639,7 @@ static void armv7m_nvic_realize(DeviceState *dev, Error **errp)
 
     s->num_prio_bits = arm_feature(&s->cpu->env, ARM_FEATURE_V7) ? 8 : 2;
 
-    if (!sysbus_realize(SYS_BUS_DEVICE(&s->systick[M_REG_NS]), &err)) {
-        error_propagate(errp, err);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->systick[M_REG_NS]), errp)) {
         return;
     }
     sysbus_connect_irq(SYS_BUS_DEVICE(&s->systick[M_REG_NS]), 0,
@@ -2656,8 +2654,7 @@ static void armv7m_nvic_realize(DeviceState *dev, Error **errp)
         object_initialize_child(OBJECT(dev), "systick-reg-s",
                                 &s->systick[M_REG_S], TYPE_SYSTICK);
 
-        if (!sysbus_realize(SYS_BUS_DEVICE(&s->systick[M_REG_S]), &err)) {
-            error_propagate(errp, err);
+        if (!sysbus_realize(SYS_BUS_DEVICE(&s->systick[M_REG_S]), errp)) {
             return;
         }
         sysbus_connect_irq(SYS_BUS_DEVICE(&s->systick[M_REG_S]), 0,
diff --git a/hw/intc/pnv_xive.c b/hw/intc/pnv_xive.c
index d6780061f4..5f69626b3a 100644
--- a/hw/intc/pnv_xive.c
+++ b/hw/intc/pnv_xive.c
@@ -1832,8 +1832,7 @@ static void pnv_xive_realize(DeviceState *dev, Error **errp)
     object_property_set_int(OBJECT(xsrc), "nr-irqs", PNV_XIVE_NR_IRQS,
                             &error_fatal);
     object_property_set_link(OBJECT(xsrc), "xive", OBJECT(xive), &error_abort);
-    if (!qdev_realize(DEVICE(xsrc), NULL, &local_err)) {
-        error_propagate(errp, local_err);
+    if (!qdev_realize(DEVICE(xsrc), NULL, errp)) {
         return;
     }
 
@@ -1841,8 +1840,7 @@ static void pnv_xive_realize(DeviceState *dev, Error **errp)
                             &error_fatal);
     object_property_set_link(OBJECT(end_xsrc), "xive", OBJECT(xive),
                              &error_abort);
-    if (!qdev_realize(DEVICE(end_xsrc), NULL, &local_err)) {
-        error_propagate(errp, local_err);
+    if (!qdev_realize(DEVICE(end_xsrc), NULL, errp)) {
         return;
     }
 
diff --git a/hw/intc/realview_gic.c b/hw/intc/realview_gic.c
index aa0010e91f..9b12116b2a 100644
--- a/hw/intc/realview_gic.c
+++ b/hw/intc/realview_gic.c
@@ -26,7 +26,6 @@ static void realview_gic_realize(DeviceState *dev, Error **errp)
     SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
     RealViewGICState *s = REALVIEW_GIC(dev);
     SysBusDevice *busdev;
-    Error *err = NULL;
     /* The GICs on the RealView boards have a fixed nonconfigurable
      * number of interrupt lines, so we don't need to expose this as
      * a qdev property.
@@ -34,8 +33,7 @@ static void realview_gic_realize(DeviceState *dev, Error **errp)
     int numirq = 96;
 
     qdev_prop_set_uint32(DEVICE(&s->gic), "num-irq", numirq);
-    if (!sysbus_realize(SYS_BUS_DEVICE(&s->gic), &err)) {
-        error_propagate(errp, err);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->gic), errp)) {
         return;
     }
     busdev = SYS_BUS_DEVICE(&s->gic);
diff --git a/hw/intc/spapr_xive.c b/hw/intc/spapr_xive.c
index 1f42bf4f43..89c8cd9667 100644
--- a/hw/intc/spapr_xive.c
+++ b/hw/intc/spapr_xive.c
@@ -311,8 +311,7 @@ static void spapr_xive_realize(DeviceState *dev, Error **errp)
     object_property_set_int(OBJECT(xsrc), "nr-irqs", xive->nr_irqs,
                             &error_fatal);
     object_property_set_link(OBJECT(xsrc), "xive", OBJECT(xive), &error_abort);
-    if (!qdev_realize(DEVICE(xsrc), NULL, &local_err)) {
-        error_propagate(errp, local_err);
+    if (!qdev_realize(DEVICE(xsrc), NULL, errp)) {
         return;
     }
     sysbus_init_mmio(SYS_BUS_DEVICE(xive), &xsrc->esb_mmio);
@@ -324,8 +323,7 @@ static void spapr_xive_realize(DeviceState *dev, Error **errp)
                             &error_fatal);
     object_property_set_link(OBJECT(end_xsrc), "xive", OBJECT(xive),
                              &error_abort);
-    if (!qdev_realize(DEVICE(end_xsrc), NULL, &local_err)) {
-        error_propagate(errp, local_err);
+    if (!qdev_realize(DEVICE(end_xsrc), NULL, errp)) {
         return;
     }
     sysbus_init_mmio(SYS_BUS_DEVICE(xive), &end_xsrc->esb_mmio);
diff --git a/hw/intc/xics_kvm.c b/hw/intc/xics_kvm.c
index 8d6156578f..68bb1914b9 100644
--- a/hw/intc/xics_kvm.c
+++ b/hw/intc/xics_kvm.c
@@ -309,16 +309,14 @@ int ics_set_kvm_state(ICSState *ics, Error **errp)
     }
 
     for (i = 0; i < ics->nr_irqs; i++) {
-        Error *local_err = NULL;
         int ret;
 
         if (ics_irq_free(ics, i)) {
             continue;
         }
 
-        ret = ics_set_kvm_state_one(ics, i, &local_err);
+        ret = ics_set_kvm_state_one(ics, i, errp);
         if (ret < 0) {
-            error_propagate(errp, local_err);
             return ret;
         }
     }