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>

3 files changed, 8 insertions, 19 deletions

diff --git a/hw/misc/macio/cuda.c b/hw/misc/macio/cuda.c
index cc7c26d..286e7a5 100644
--- a/hw/misc/macio/cuda.c
+++ b/hw/misc/macio/cuda.c
@@ -521,13 +521,11 @@ static void cuda_reset(DeviceState *dev)
 static void cuda_realize(DeviceState *dev, Error **errp)
 {
     CUDAState *s = CUDA(dev);
-    Error *err = NULL;
     SysBusDevice *sbd;
     ADBBusState *adb_bus = &s->adb_bus;
     struct tm tm;
 
-    if (!sysbus_realize(SYS_BUS_DEVICE(&s->mos6522_cuda), &err)) {
-        error_propagate(errp, err);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->mos6522_cuda), errp)) {
         return;
     }
 
diff --git a/hw/misc/macio/macio.c b/hw/misc/macio/macio.c
index 9b6e3f1..6797226 100644
--- a/hw/misc/macio/macio.c
+++ b/hw/misc/macio/macio.c
@@ -98,10 +98,8 @@ static void macio_common_realize(PCIDevice *d, Error **errp)
 {
     MacIOState *s = MACIO(d);
     SysBusDevice *sysbus_dev;
-    Error *err = NULL;
 
-    if (!qdev_realize(DEVICE(&s->dbdma), BUS(&s->macio_bus), &err)) {
-        error_propagate(errp, err);
+    if (!qdev_realize(DEVICE(&s->dbdma), BUS(&s->macio_bus), errp)) {
         return;
     }
     sysbus_dev = SYS_BUS_DEVICE(&s->dbdma);
@@ -115,8 +113,7 @@ static void macio_common_realize(PCIDevice *d, Error **errp)
     qdev_prop_set_chr(DEVICE(&s->escc), "chrB", serial_hd(1));
     qdev_prop_set_uint32(DEVICE(&s->escc), "chnBtype", escc_serial);
     qdev_prop_set_uint32(DEVICE(&s->escc), "chnAtype", escc_serial);
-    if (!qdev_realize(DEVICE(&s->escc), BUS(&s->macio_bus), &err)) {
-        error_propagate(errp, err);
+    if (!qdev_realize(DEVICE(&s->escc), BUS(&s->macio_bus), errp)) {
         return;
     }
 
@@ -157,8 +154,7 @@ static void macio_oldworld_realize(PCIDevice *d, Error **errp)
 
     qdev_prop_set_uint64(DEVICE(&s->cuda), "timebase-frequency",
                          s->frequency);
-    if (!qdev_realize(DEVICE(&s->cuda), BUS(&s->macio_bus), &err)) {
-        error_propagate(errp, err);
+    if (!qdev_realize(DEVICE(&s->cuda), BUS(&s->macio_bus), errp)) {
         return;
     }
     sysbus_dev = SYS_BUS_DEVICE(&s->cuda);
@@ -173,8 +169,7 @@ static void macio_oldworld_realize(PCIDevice *d, Error **errp)
     sysbus_connect_irq(sysbus_dev, 1, qdev_get_gpio_in(pic_dev,
                                                        OLDWORLD_ESCCA_IRQ));
 
-    if (!qdev_realize(DEVICE(&os->nvram), BUS(&s->macio_bus), &err)) {
-        error_propagate(errp, err);
+    if (!qdev_realize(DEVICE(&os->nvram), BUS(&s->macio_bus), errp)) {
         return;
     }
     sysbus_dev = SYS_BUS_DEVICE(&os->nvram);
@@ -343,8 +338,7 @@ static void macio_newworld_realize(PCIDevice *d, Error **errp)
         object_property_set_link(OBJECT(&s->pmu), "gpio", OBJECT(sysbus_dev),
                                  &error_abort);
         qdev_prop_set_bit(DEVICE(&s->pmu), "has-adb", ns->has_adb);
-        if (!qdev_realize(DEVICE(&s->pmu), BUS(&s->macio_bus), &err)) {
-            error_propagate(errp, err);
+        if (!qdev_realize(DEVICE(&s->pmu), BUS(&s->macio_bus), errp)) {
             return;
         }
         sysbus_dev = SYS_BUS_DEVICE(&s->pmu);
@@ -360,8 +354,7 @@ static void macio_newworld_realize(PCIDevice *d, Error **errp)
         qdev_prop_set_uint64(DEVICE(&s->cuda), "timebase-frequency",
                              s->frequency);
 
-        if (!qdev_realize(DEVICE(&s->cuda), BUS(&s->macio_bus), &err)) {
-            error_propagate(errp, err);
+        if (!qdev_realize(DEVICE(&s->cuda), BUS(&s->macio_bus), errp)) {
             return;
         }
         sysbus_dev = SYS_BUS_DEVICE(&s->cuda);
diff --git a/hw/misc/macio/pmu.c b/hw/misc/macio/pmu.c
index 42ba963..0902299 100644
--- a/hw/misc/macio/pmu.c
+++ b/hw/misc/macio/pmu.c
@@ -735,13 +735,11 @@ static void pmu_reset(DeviceState *dev)
 static void pmu_realize(DeviceState *dev, Error **errp)
 {
     PMUState *s = VIA_PMU(dev);
-    Error *err = NULL;
     SysBusDevice *sbd;
     ADBBusState *adb_bus = &s->adb_bus;
     struct tm tm;
 
-    if (!sysbus_realize(SYS_BUS_DEVICE(&s->mos6522_pmu), &err)) {
-        error_propagate(errp, err);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->mos6522_pmu), errp)) {
         return;
     }