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>

1 files changed, 16 insertions, 32 deletions

diff --git a/hw/arm/bcm2835_peripherals.c b/hw/arm/bcm2835_peripherals.c
index cb724c18e8..a9d7f53f6e 100644
--- a/hw/arm/bcm2835_peripherals.c
+++ b/hw/arm/bcm2835_peripherals.c
@@ -156,8 +156,7 @@ static void bcm2835_peripherals_realize(DeviceState *dev, Error **errp)
     }
 
     /* Interrupt Controller */
-    if (!sysbus_realize(SYS_BUS_DEVICE(&s->ic), &err)) {
-        error_propagate(errp, err);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->ic), errp)) {
         return;
     }
 
@@ -166,8 +165,7 @@ static void bcm2835_peripherals_realize(DeviceState *dev, Error **errp)
     sysbus_pass_irq(SYS_BUS_DEVICE(s), SYS_BUS_DEVICE(&s->ic));
 
     /* Sys Timer */
-    if (!sysbus_realize(SYS_BUS_DEVICE(&s->systmr), &err)) {
-        error_propagate(errp, err);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->systmr), errp)) {
         return;
     }
     memory_region_add_subregion(&s->peri_mr, ST_OFFSET,
@@ -178,8 +176,7 @@ static void bcm2835_peripherals_realize(DeviceState *dev, Error **errp)
 
     /* UART0 */
     qdev_prop_set_chr(DEVICE(&s->uart0), "chardev", serial_hd(0));
-    if (!sysbus_realize(SYS_BUS_DEVICE(&s->uart0), &err)) {
-        error_propagate(errp, err);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->uart0), errp)) {
         return;
     }
 
@@ -192,8 +189,7 @@ static void bcm2835_peripherals_realize(DeviceState *dev, Error **errp)
     /* AUX / UART1 */
     qdev_prop_set_chr(DEVICE(&s->aux), "chardev", serial_hd(1));
 
-    if (!sysbus_realize(SYS_BUS_DEVICE(&s->aux), &err)) {
-        error_propagate(errp, err);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->aux), errp)) {
         return;
     }
 
@@ -204,8 +200,7 @@ static void bcm2835_peripherals_realize(DeviceState *dev, Error **errp)
                                INTERRUPT_AUX));
 
     /* Mailboxes */
-    if (!sysbus_realize(SYS_BUS_DEVICE(&s->mboxes), &err)) {
-        error_propagate(errp, err);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->mboxes), errp)) {
         return;
     }
 
@@ -223,13 +218,11 @@ static void bcm2835_peripherals_realize(DeviceState *dev, Error **errp)
     }
 
     if (!object_property_set_uint(OBJECT(&s->fb), "vcram-base",
-                                  ram_size - vcram_size, &err)) {
-        error_propagate(errp, err);
+                                  ram_size - vcram_size, errp)) {
         return;
     }
 
-    if (!sysbus_realize(SYS_BUS_DEVICE(&s->fb), &err)) {
-        error_propagate(errp, err);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->fb), errp)) {
         return;
     }
 
@@ -239,8 +232,7 @@ static void bcm2835_peripherals_realize(DeviceState *dev, Error **errp)
                        qdev_get_gpio_in(DEVICE(&s->mboxes), MBOX_CHAN_FB));
 
     /* Property channel */
-    if (!sysbus_realize(SYS_BUS_DEVICE(&s->property), &err)) {
-        error_propagate(errp, err);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->property), errp)) {
         return;
     }
 
@@ -251,8 +243,7 @@ static void bcm2835_peripherals_realize(DeviceState *dev, Error **errp)
                       qdev_get_gpio_in(DEVICE(&s->mboxes), MBOX_CHAN_PROPERTY));
 
     /* Random Number Generator */
-    if (!sysbus_realize(SYS_BUS_DEVICE(&s->rng), &err)) {
-        error_propagate(errp, err);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->rng), errp)) {
         return;
     }
 
@@ -275,8 +266,7 @@ static void bcm2835_peripherals_realize(DeviceState *dev, Error **errp)
                              BCM2835_SDHC_CAPAREG, &error_abort);
     object_property_set_bool(OBJECT(&s->sdhci), "pending-insert-quirk", true,
                              &error_abort);
-    if (!sysbus_realize(SYS_BUS_DEVICE(&s->sdhci), &err)) {
-        error_propagate(errp, err);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->sdhci), errp)) {
         return;
     }
 
@@ -287,8 +277,7 @@ static void bcm2835_peripherals_realize(DeviceState *dev, Error **errp)
                                INTERRUPT_ARASANSDIO));
 
     /* SDHOST */
-    if (!sysbus_realize(SYS_BUS_DEVICE(&s->sdhost), &err)) {
-        error_propagate(errp, err);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->sdhost), errp)) {
         return;
     }
 
@@ -299,8 +288,7 @@ static void bcm2835_peripherals_realize(DeviceState *dev, Error **errp)
                                INTERRUPT_SDIO));
 
     /* DMA Channels */
-    if (!sysbus_realize(SYS_BUS_DEVICE(&s->dma), &err)) {
-        error_propagate(errp, err);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->dma), errp)) {
         return;
     }
 
@@ -317,16 +305,14 @@ static void bcm2835_peripherals_realize(DeviceState *dev, Error **errp)
     }
 
     /* THERMAL */
-    if (!sysbus_realize(SYS_BUS_DEVICE(&s->thermal), &err)) {
-        error_propagate(errp, err);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->thermal), errp)) {
         return;
     }
     memory_region_add_subregion(&s->peri_mr, THERMAL_OFFSET,
                 sysbus_mmio_get_region(SYS_BUS_DEVICE(&s->thermal), 0));
 
     /* GPIO */
-    if (!sysbus_realize(SYS_BUS_DEVICE(&s->gpio), &err)) {
-        error_propagate(errp, err);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->gpio), errp)) {
         return;
     }
 
@@ -336,8 +322,7 @@ static void bcm2835_peripherals_realize(DeviceState *dev, Error **errp)
     object_property_add_alias(OBJECT(s), "sd-bus", OBJECT(&s->gpio), "sd-bus");
 
     /* Mphi */
-    if (!sysbus_realize(SYS_BUS_DEVICE(&s->mphi), &err)) {
-        error_propagate(errp, err);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->mphi), errp)) {
         return;
     }
 
@@ -348,8 +333,7 @@ static void bcm2835_peripherals_realize(DeviceState *dev, Error **errp)
                                INTERRUPT_HOSTPORT));
 
     /* DWC2 */
-    if (!sysbus_realize(SYS_BUS_DEVICE(&s->dwc2), &err)) {
-        error_propagate(errp, err);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->dwc2), errp)) {
         return;
     }