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/aspeed_soc.c b/hw/arm/aspeed_soc.c
index ff5f4d6a52..a1a8684216 100644
--- a/hw/arm/aspeed_soc.c
+++ b/hw/arm/aspeed_soc.c
@@ -230,8 +230,7 @@ static void aspeed_soc_realize(DeviceState *dev, Error **errp)
 
     /* CPU */
     for (i = 0; i < sc->num_cpus; i++) {
-        if (!qdev_realize(DEVICE(&s->cpu[i]), NULL, &err)) {
-            error_propagate(errp, err);
+        if (!qdev_realize(DEVICE(&s->cpu[i]), NULL, errp)) {
             return;
         }
     }
@@ -247,15 +246,13 @@ static void aspeed_soc_realize(DeviceState *dev, Error **errp)
                                 sc->memmap[ASPEED_SRAM], &s->sram);
 
     /* SCU */
-    if (!sysbus_realize(SYS_BUS_DEVICE(&s->scu), &err)) {
-        error_propagate(errp, err);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->scu), errp)) {
         return;
     }
     sysbus_mmio_map(SYS_BUS_DEVICE(&s->scu), 0, sc->memmap[ASPEED_SCU]);
 
     /* VIC */
-    if (!sysbus_realize(SYS_BUS_DEVICE(&s->vic), &err)) {
-        error_propagate(errp, err);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->vic), errp)) {
         return;
     }
     sysbus_mmio_map(SYS_BUS_DEVICE(&s->vic), 0, sc->memmap[ASPEED_VIC]);
@@ -265,8 +262,7 @@ static void aspeed_soc_realize(DeviceState *dev, Error **errp)
                        qdev_get_gpio_in(DEVICE(&s->cpu), ARM_CPU_FIQ));
 
     /* RTC */
-    if (!sysbus_realize(SYS_BUS_DEVICE(&s->rtc), &err)) {
-        error_propagate(errp, err);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->rtc), errp)) {
         return;
     }
     sysbus_mmio_map(SYS_BUS_DEVICE(&s->rtc), 0, sc->memmap[ASPEED_RTC]);
@@ -276,8 +272,7 @@ static void aspeed_soc_realize(DeviceState *dev, Error **errp)
     /* Timer */
     object_property_set_link(OBJECT(&s->timerctrl), "scu", OBJECT(&s->scu),
                              &error_abort);
-    if (!sysbus_realize(SYS_BUS_DEVICE(&s->timerctrl), &err)) {
-        error_propagate(errp, err);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->timerctrl), errp)) {
         return;
     }
     sysbus_mmio_map(SYS_BUS_DEVICE(&s->timerctrl), 0,
@@ -297,8 +292,7 @@ static void aspeed_soc_realize(DeviceState *dev, Error **errp)
     /* I2C */
     object_property_set_link(OBJECT(&s->i2c), "dram", OBJECT(s->dram_mr),
                              &error_abort);
-    if (!sysbus_realize(SYS_BUS_DEVICE(&s->i2c), &err)) {
-        error_propagate(errp, err);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->i2c), errp)) {
         return;
     }
     sysbus_mmio_map(SYS_BUS_DEVICE(&s->i2c), 0, sc->memmap[ASPEED_I2C]);
@@ -309,12 +303,10 @@ static void aspeed_soc_realize(DeviceState *dev, Error **errp)
     object_property_set_link(OBJECT(&s->fmc), "dram", OBJECT(s->dram_mr),
                              &error_abort);
     if (!object_property_set_int(OBJECT(&s->fmc), "sdram-base",
-                                 sc->memmap[ASPEED_SDRAM], &err)) {
-        error_propagate(errp, err);
+                                 sc->memmap[ASPEED_SDRAM], errp)) {
         return;
     }
-    if (!sysbus_realize(SYS_BUS_DEVICE(&s->fmc), &err)) {
-        error_propagate(errp, err);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->fmc), errp)) {
         return;
     }
     sysbus_mmio_map(SYS_BUS_DEVICE(&s->fmc), 0, sc->memmap[ASPEED_FMC]);
@@ -326,8 +318,7 @@ static void aspeed_soc_realize(DeviceState *dev, Error **errp)
     /* SPI */
     for (i = 0; i < sc->spis_num; i++) {
         object_property_set_int(OBJECT(&s->spi[i]), "num-cs", 1, &error_abort);
-        if (!sysbus_realize(SYS_BUS_DEVICE(&s->spi[i]), &err)) {
-            error_propagate(errp, err);
+        if (!sysbus_realize(SYS_BUS_DEVICE(&s->spi[i]), errp)) {
             return;
         }
         sysbus_mmio_map(SYS_BUS_DEVICE(&s->spi[i]), 0,
@@ -338,8 +329,7 @@ static void aspeed_soc_realize(DeviceState *dev, Error **errp)
 
     /* EHCI */
     for (i = 0; i < sc->ehcis_num; i++) {
-        if (!sysbus_realize(SYS_BUS_DEVICE(&s->ehci[i]), &err)) {
-            error_propagate(errp, err);
+        if (!sysbus_realize(SYS_BUS_DEVICE(&s->ehci[i]), errp)) {
             return;
         }
         sysbus_mmio_map(SYS_BUS_DEVICE(&s->ehci[i]), 0,
@@ -349,8 +339,7 @@ static void aspeed_soc_realize(DeviceState *dev, Error **errp)
     }
 
     /* SDMC - SDRAM Memory Controller */
-    if (!sysbus_realize(SYS_BUS_DEVICE(&s->sdmc), &err)) {
-        error_propagate(errp, err);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->sdmc), errp)) {
         return;
     }
     sysbus_mmio_map(SYS_BUS_DEVICE(&s->sdmc), 0, sc->memmap[ASPEED_SDMC]);
@@ -361,8 +350,7 @@ static void aspeed_soc_realize(DeviceState *dev, Error **errp)
 
         object_property_set_link(OBJECT(&s->wdt[i]), "scu", OBJECT(&s->scu),
                                  &error_abort);
-        if (!sysbus_realize(SYS_BUS_DEVICE(&s->wdt[i]), &err)) {
-            error_propagate(errp, err);
+        if (!sysbus_realize(SYS_BUS_DEVICE(&s->wdt[i]), errp)) {
             return;
         }
         sysbus_mmio_map(SYS_BUS_DEVICE(&s->wdt[i]), 0,
@@ -373,8 +361,7 @@ static void aspeed_soc_realize(DeviceState *dev, Error **errp)
     for (i = 0; i < sc->macs_num; i++) {
         object_property_set_bool(OBJECT(&s->ftgmac100[i]), "aspeed", true,
                                  &error_abort);
-        if (!sysbus_realize(SYS_BUS_DEVICE(&s->ftgmac100[i]), &err)) {
-            error_propagate(errp, err);
+        if (!sysbus_realize(SYS_BUS_DEVICE(&s->ftgmac100[i]), errp)) {
             return;
         }
         sysbus_mmio_map(SYS_BUS_DEVICE(&s->ftgmac100[i]), 0,
@@ -384,8 +371,7 @@ static void aspeed_soc_realize(DeviceState *dev, Error **errp)
     }
 
     /* XDMA */
-    if (!sysbus_realize(SYS_BUS_DEVICE(&s->xdma), &err)) {
-        error_propagate(errp, err);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->xdma), errp)) {
         return;
     }
     sysbus_mmio_map(SYS_BUS_DEVICE(&s->xdma), 0,
@@ -394,8 +380,7 @@ static void aspeed_soc_realize(DeviceState *dev, Error **errp)
                        aspeed_soc_get_irq(s, ASPEED_XDMA));
 
     /* GPIO */
-    if (!sysbus_realize(SYS_BUS_DEVICE(&s->gpio), &err)) {
-        error_propagate(errp, err);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->gpio), errp)) {
         return;
     }
     sysbus_mmio_map(SYS_BUS_DEVICE(&s->gpio), 0, sc->memmap[ASPEED_GPIO]);
@@ -403,8 +388,7 @@ static void aspeed_soc_realize(DeviceState *dev, Error **errp)
                        aspeed_soc_get_irq(s, ASPEED_GPIO));
 
     /* SDHCI */
-    if (!sysbus_realize(SYS_BUS_DEVICE(&s->sdhci), &err)) {
-        error_propagate(errp, err);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->sdhci), errp)) {
         return;
     }
     sysbus_mmio_map(SYS_BUS_DEVICE(&s->sdhci), 0,