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, 12 insertions, 24 deletions

diff --git a/hw/arm/fsl-imx6.c b/hw/arm/fsl-imx6.c
index e359ee579d..0bc9f0b60d 100644
--- a/hw/arm/fsl-imx6.c
+++ b/hw/arm/fsl-imx6.c
@@ -130,8 +130,7 @@ static void fsl_imx6_realize(DeviceState *dev, Error **errp)
                                      true, &error_abort);
         }
 
-        if (!qdev_realize(DEVICE(&s->cpu[i]), NULL, &err)) {
-            error_propagate(errp, err);
+        if (!qdev_realize(DEVICE(&s->cpu[i]), NULL, errp)) {
             return;
         }
     }
@@ -142,8 +141,7 @@ static void fsl_imx6_realize(DeviceState *dev, Error **errp)
     object_property_set_int(OBJECT(&s->a9mpcore), "num-irq",
                             FSL_IMX6_MAX_IRQ + GIC_INTERNAL, &error_abort);
 
-    if (!sysbus_realize(SYS_BUS_DEVICE(&s->a9mpcore), &err)) {
-        error_propagate(errp, err);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->a9mpcore), errp)) {
         return;
     }
     sysbus_mmio_map(SYS_BUS_DEVICE(&s->a9mpcore), 0, FSL_IMX6_A9MPCORE_ADDR);
@@ -155,14 +153,12 @@ static void fsl_imx6_realize(DeviceState *dev, Error **errp)
                            qdev_get_gpio_in(DEVICE(&s->cpu[i]), ARM_CPU_FIQ));
     }
 
-    if (!sysbus_realize(SYS_BUS_DEVICE(&s->ccm), &err)) {
-        error_propagate(errp, err);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->ccm), errp)) {
         return;
     }
     sysbus_mmio_map(SYS_BUS_DEVICE(&s->ccm), 0, FSL_IMX6_CCM_ADDR);
 
-    if (!sysbus_realize(SYS_BUS_DEVICE(&s->src), &err)) {
-        error_propagate(errp, err);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->src), errp)) {
         return;
     }
     sysbus_mmio_map(SYS_BUS_DEVICE(&s->src), 0, FSL_IMX6_SRC_ADDR);
@@ -182,8 +178,7 @@ static void fsl_imx6_realize(DeviceState *dev, Error **errp)
 
         qdev_prop_set_chr(DEVICE(&s->uart[i]), "chardev", serial_hd(i));
 
-        if (!sysbus_realize(SYS_BUS_DEVICE(&s->uart[i]), &err)) {
-            error_propagate(errp, err);
+        if (!sysbus_realize(SYS_BUS_DEVICE(&s->uart[i]), errp)) {
             return;
         }
 
@@ -195,8 +190,7 @@ static void fsl_imx6_realize(DeviceState *dev, Error **errp)
 
     s->gpt.ccm = IMX_CCM(&s->ccm);
 
-    if (!sysbus_realize(SYS_BUS_DEVICE(&s->gpt), &err)) {
-        error_propagate(errp, err);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->gpt), errp)) {
         return;
     }
 
@@ -217,8 +211,7 @@ static void fsl_imx6_realize(DeviceState *dev, Error **errp)
 
         s->epit[i].ccm = IMX_CCM(&s->ccm);
 
-        if (!sysbus_realize(SYS_BUS_DEVICE(&s->epit[i]), &err)) {
-            error_propagate(errp, err);
+        if (!sysbus_realize(SYS_BUS_DEVICE(&s->epit[i]), errp)) {
             return;
         }
 
@@ -239,8 +232,7 @@ static void fsl_imx6_realize(DeviceState *dev, Error **errp)
             { FSL_IMX6_I2C3_ADDR, FSL_IMX6_I2C3_IRQ }
         };
 
-        if (!sysbus_realize(SYS_BUS_DEVICE(&s->i2c[i]), &err)) {
-            error_propagate(errp, err);
+        if (!sysbus_realize(SYS_BUS_DEVICE(&s->i2c[i]), errp)) {
             return;
         }
 
@@ -298,8 +290,7 @@ static void fsl_imx6_realize(DeviceState *dev, Error **errp)
                                  &error_abort);
         object_property_set_bool(OBJECT(&s->gpio[i]), "has-upper-pin-irq",
                                  true, &error_abort);
-        if (!sysbus_realize(SYS_BUS_DEVICE(&s->gpio[i]), &err)) {
-            error_propagate(errp, err);
+        if (!sysbus_realize(SYS_BUS_DEVICE(&s->gpio[i]), errp)) {
             return;
         }
 
@@ -331,8 +322,7 @@ static void fsl_imx6_realize(DeviceState *dev, Error **errp)
                                  IMX6_ESDHC_CAPABILITIES, &error_abort);
         object_property_set_uint(OBJECT(&s->esdhc[i]), "vendor",
                                  SDHCI_VENDOR_IMX, &error_abort);
-        if (!sysbus_realize(SYS_BUS_DEVICE(&s->esdhc[i]), &err)) {
-            error_propagate(errp, err);
+        if (!sysbus_realize(SYS_BUS_DEVICE(&s->esdhc[i]), errp)) {
             return;
         }
         sysbus_mmio_map(SYS_BUS_DEVICE(&s->esdhc[i]), 0, esdhc_table[i].addr);
@@ -377,8 +367,7 @@ static void fsl_imx6_realize(DeviceState *dev, Error **errp)
         };
 
         /* Initialize the SPI */
-        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;
         }
 
@@ -389,8 +378,7 @@ static void fsl_imx6_realize(DeviceState *dev, Error **errp)
     }
 
     qdev_set_nic_properties(DEVICE(&s->eth), &nd_table[0]);
-    if (!sysbus_realize(SYS_BUS_DEVICE(&s->eth), &err)) {
-        error_propagate(errp, err);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->eth), errp)) {
         return;
     }
     sysbus_mmio_map(SYS_BUS_DEVICE(&s->eth), 0, FSL_IMX6_ENET_ADDR);