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, 13 insertions, 27 deletions

diff --git a/hw/ppc/pnv.c b/hw/ppc/pnv.c
index 194b457..6670967 100644
--- a/hw/ppc/pnv.c
+++ b/hw/ppc/pnv.c
@@ -1140,8 +1140,7 @@ static void pnv_chip_power8_realize(DeviceState *dev, Error **errp)
                             &error_fatal);
     object_property_set_link(OBJECT(&chip8->psi), ICS_PROP_XICS,
                              OBJECT(chip8->xics), &error_abort);
-    if (!qdev_realize(DEVICE(&chip8->psi), NULL, &local_err)) {
-        error_propagate(errp, local_err);
+    if (!qdev_realize(DEVICE(&chip8->psi), NULL, errp)) {
         return;
     }
     pnv_xscom_add_subregion(chip, PNV_XSCOM_PSIHB_BASE,
@@ -1170,8 +1169,7 @@ static void pnv_chip_power8_realize(DeviceState *dev, Error **errp)
     /* Create the simplified OCC model */
     object_property_set_link(OBJECT(&chip8->occ), "psi", OBJECT(&chip8->psi),
                              &error_abort);
-    if (!qdev_realize(DEVICE(&chip8->occ), NULL, &local_err)) {
-        error_propagate(errp, local_err);
+    if (!qdev_realize(DEVICE(&chip8->occ), NULL, errp)) {
         return;
     }
     pnv_xscom_add_subregion(chip, PNV_XSCOM_OCC_BASE, &chip8->occ.xscom_regs);
@@ -1183,8 +1181,7 @@ static void pnv_chip_power8_realize(DeviceState *dev, Error **errp)
     /* HOMER */
     object_property_set_link(OBJECT(&chip8->homer), "chip", OBJECT(chip),
                              &error_abort);
-    if (!qdev_realize(DEVICE(&chip8->homer), NULL, &local_err)) {
-        error_propagate(errp, local_err);
+    if (!qdev_realize(DEVICE(&chip8->homer), NULL, errp)) {
         return;
     }
     /* Homer Xscom region */
@@ -1202,8 +1199,7 @@ static void pnv_chip_power8_realize(DeviceState *dev, Error **errp)
         object_property_set_int(OBJECT(phb), "index", i, &error_fatal);
         object_property_set_int(OBJECT(phb), "chip-id", chip->chip_id,
                                 &error_fatal);
-        if (!sysbus_realize(SYS_BUS_DEVICE(phb), &local_err)) {
-            error_propagate(errp, local_err);
+        if (!sysbus_realize(SYS_BUS_DEVICE(phb), errp)) {
             return;
         }
 
@@ -1358,7 +1354,6 @@ static void pnv_chip_quad_realize(Pnv9Chip *chip9, Error **errp)
 static void pnv_chip_power9_phb_realize(PnvChip *chip, Error **errp)
 {
     Pnv9Chip *chip9 = PNV9_CHIP(chip);
-    Error *local_err = NULL;
     int i, j;
     int phb_id = 0;
 
@@ -1380,8 +1375,7 @@ static void pnv_chip_power9_phb_realize(PnvChip *chip, Error **errp)
                                 &error_fatal);
         object_property_set_link(OBJECT(pec), "system-memory",
                                  OBJECT(get_system_memory()), &error_abort);
-        if (!qdev_realize(DEVICE(pec), NULL, &local_err)) {
-            error_propagate(errp, local_err);
+        if (!qdev_realize(DEVICE(pec), NULL, errp)) {
             return;
         }
 
@@ -1405,8 +1399,7 @@ static void pnv_chip_power9_phb_realize(PnvChip *chip, Error **errp)
                                     &error_fatal);
             object_property_set_link(obj, "stack", OBJECT(stack),
                                      &error_abort);
-            if (!sysbus_realize(SYS_BUS_DEVICE(obj), &local_err)) {
-                error_propagate(errp, local_err);
+            if (!sysbus_realize(SYS_BUS_DEVICE(obj), errp)) {
                 return;
             }
 
@@ -1464,8 +1457,7 @@ static void pnv_chip_power9_realize(DeviceState *dev, Error **errp)
                             PNV9_XIVE_TM_BASE(chip), &error_fatal);
     object_property_set_link(OBJECT(&chip9->xive), "chip", OBJECT(chip),
                              &error_abort);
-    if (!sysbus_realize(SYS_BUS_DEVICE(&chip9->xive), &local_err)) {
-        error_propagate(errp, local_err);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&chip9->xive), errp)) {
         return;
     }
     pnv_xscom_add_subregion(chip, PNV9_XSCOM_XIVE_BASE,
@@ -1474,8 +1466,7 @@ static void pnv_chip_power9_realize(DeviceState *dev, Error **errp)
     /* Processor Service Interface (PSI) Host Bridge */
     object_property_set_int(OBJECT(&chip9->psi), "bar", PNV9_PSIHB_BASE(chip),
                             &error_fatal);
-    if (!qdev_realize(DEVICE(&chip9->psi), NULL, &local_err)) {
-        error_propagate(errp, local_err);
+    if (!qdev_realize(DEVICE(&chip9->psi), NULL, errp)) {
         return;
     }
     pnv_xscom_add_subregion(chip, PNV9_XSCOM_PSIHB_BASE,
@@ -1484,8 +1475,7 @@ static void pnv_chip_power9_realize(DeviceState *dev, Error **errp)
     /* LPC */
     object_property_set_link(OBJECT(&chip9->lpc), "psi", OBJECT(&chip9->psi),
                              &error_abort);
-    if (!qdev_realize(DEVICE(&chip9->lpc), NULL, &local_err)) {
-        error_propagate(errp, local_err);
+    if (!qdev_realize(DEVICE(&chip9->lpc), NULL, errp)) {
         return;
     }
     memory_region_add_subregion(get_system_memory(), PNV9_LPCM_BASE(chip),
@@ -1497,8 +1487,7 @@ static void pnv_chip_power9_realize(DeviceState *dev, Error **errp)
     /* Create the simplified OCC model */
     object_property_set_link(OBJECT(&chip9->occ), "psi", OBJECT(&chip9->psi),
                              &error_abort);
-    if (!qdev_realize(DEVICE(&chip9->occ), NULL, &local_err)) {
-        error_propagate(errp, local_err);
+    if (!qdev_realize(DEVICE(&chip9->occ), NULL, errp)) {
         return;
     }
     pnv_xscom_add_subregion(chip, PNV9_XSCOM_OCC_BASE, &chip9->occ.xscom_regs);
@@ -1510,8 +1499,7 @@ static void pnv_chip_power9_realize(DeviceState *dev, Error **errp)
     /* HOMER */
     object_property_set_link(OBJECT(&chip9->homer), "chip", OBJECT(chip),
                              &error_abort);
-    if (!qdev_realize(DEVICE(&chip9->homer), NULL, &local_err)) {
-        error_propagate(errp, local_err);
+    if (!qdev_realize(DEVICE(&chip9->homer), NULL, errp)) {
         return;
     }
     /* Homer Xscom region */
@@ -1591,8 +1579,7 @@ static void pnv_chip_power10_realize(DeviceState *dev, Error **errp)
     /* Processor Service Interface (PSI) Host Bridge */
     object_property_set_int(OBJECT(&chip10->psi), "bar",
                             PNV10_PSIHB_BASE(chip), &error_fatal);
-    if (!qdev_realize(DEVICE(&chip10->psi), NULL, &local_err)) {
-        error_propagate(errp, local_err);
+    if (!qdev_realize(DEVICE(&chip10->psi), NULL, errp)) {
         return;
     }
     pnv_xscom_add_subregion(chip, PNV10_XSCOM_PSIHB_BASE,
@@ -1601,8 +1588,7 @@ static void pnv_chip_power10_realize(DeviceState *dev, Error **errp)
     /* LPC */
     object_property_set_link(OBJECT(&chip10->lpc), "psi",
                              OBJECT(&chip10->psi), &error_abort);
-    if (!qdev_realize(DEVICE(&chip10->lpc), NULL, &local_err)) {
-        error_propagate(errp, local_err);
+    if (!qdev_realize(DEVICE(&chip10->lpc), NULL, errp)) {
         return;
     }
     memory_region_add_subregion(get_system_memory(), PNV10_LPCM_BASE(chip),