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, 16 insertions, 48 deletions

diff --git a/hw/core/machine.c b/hw/core/machine.c
index 7ff0af9..eb267b8 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -290,11 +290,9 @@ static void machine_set_phandle_start(Object *obj, Visitor *v,
                                       Error **errp)
 {
     MachineState *ms = MACHINE(obj);
-    Error *error = NULL;
     int64_t value;
 
-    if (!visit_type_int(v, name, &value, &error)) {
-        error_propagate(errp, error);
+    if (!visit_type_int(v, name, &value, errp)) {
         return;
     }
 
diff --git a/hw/core/qdev-properties-system.c b/hw/core/qdev-properties-system.c
index 7d2387f..3e4f16f 100644
--- a/hw/core/qdev-properties-system.c
+++ b/hw/core/qdev-properties-system.c
@@ -80,7 +80,6 @@ static void set_drive_helper(Object *obj, Visitor *v, const char *name,
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
-    Error *local_err = NULL;
     void **ptr = qdev_get_prop_ptr(dev, prop);
     char *str;
     BlockBackend *blk;
@@ -92,8 +91,7 @@ static void set_drive_helper(Object *obj, Visitor *v, const char *name,
         return;
     }
 
-    if (!visit_type_str(v, name, &str, &local_err)) {
-        error_propagate(errp, local_err);
+    if (!visit_type_str(v, name, &str, errp)) {
         return;
     }
 
@@ -226,7 +224,6 @@ static void set_chr(Object *obj, Visitor *v, const char *name, void *opaque,
                     Error **errp)
 {
     DeviceState *dev = DEVICE(obj);
-    Error *local_err = NULL;
     Property *prop = opaque;
     CharBackend *be = qdev_get_prop_ptr(dev, prop);
     Chardev *s;
@@ -237,8 +234,7 @@ static void set_chr(Object *obj, Visitor *v, const char *name, void *opaque,
         return;
     }
 
-    if (!visit_type_str(v, name, &str, &local_err)) {
-        error_propagate(errp, local_err);
+    if (!visit_type_str(v, name, &str, errp)) {
         return;
     }
 
@@ -305,7 +301,6 @@ static void set_netdev(Object *obj, Visitor *v, const char *name,
     NICPeers *peers_ptr = qdev_get_prop_ptr(dev, prop);
     NetClientState **ncs = peers_ptr->ncs;
     NetClientState *peers[MAX_QUEUE_NUM];
-    Error *local_err = NULL;
     int queues, err = 0, i = 0;
     char *str;
 
@@ -314,8 +309,7 @@ static void set_netdev(Object *obj, Visitor *v, const char *name,
         return;
     }
 
-    if (!visit_type_str(v, name, &str, &local_err)) {
-        error_propagate(errp, local_err);
+    if (!visit_type_str(v, name, &str, errp)) {
         return;
     }
 
@@ -386,7 +380,6 @@ static void set_audiodev(Object *obj, Visitor *v, const char* name,
     Property *prop = opaque;
     QEMUSoundCard *card = qdev_get_prop_ptr(dev, prop);
     AudioState *state;
-    Error *local_err = NULL;
     int err = 0;
     char *str;
 
@@ -395,8 +388,7 @@ static void set_audiodev(Object *obj, Visitor *v, const char* name,
         return;
     }
 
-    if (!visit_type_str(v, name, &str, &local_err)) {
-        error_propagate(errp, local_err);
+    if (!visit_type_str(v, name, &str, errp)) {
         return;
     }
 
diff --git a/hw/core/qdev-properties.c b/hw/core/qdev-properties.c
index be8d4eb..2bec8a8 100644
--- a/hw/core/qdev-properties.c
+++ b/hw/core/qdev-properties.c
@@ -117,7 +117,6 @@ static void prop_set_bit(Object *obj, Visitor *v, const char *name,
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
-    Error *local_err = NULL;
     bool value;
 
     if (dev->realized) {
@@ -125,8 +124,7 @@ static void prop_set_bit(Object *obj, Visitor *v, const char *name,
         return;
     }
 
-    if (!visit_type_bool(v, name, &value, &local_err)) {
-        error_propagate(errp, local_err);
+    if (!visit_type_bool(v, name, &value, errp)) {
         return;
     }
     bit_prop_set(dev, prop, value);
@@ -180,7 +178,6 @@ static void prop_set_bit64(Object *obj, Visitor *v, const char *name,
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
-    Error *local_err = NULL;
     bool value;
 
     if (dev->realized) {
@@ -188,8 +185,7 @@ static void prop_set_bit64(Object *obj, Visitor *v, const char *name,
         return;
     }
 
-    if (!visit_type_bool(v, name, &value, &local_err)) {
-        error_propagate(errp, local_err);
+    if (!visit_type_bool(v, name, &value, errp)) {
         return;
     }
     bit64_prop_set(dev, prop, value);
@@ -476,7 +472,6 @@ static void set_string(Object *obj, Visitor *v, const char *name,
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
     char **ptr = qdev_get_prop_ptr(dev, prop);
-    Error *local_err = NULL;
     char *str;
 
     if (dev->realized) {
@@ -484,8 +479,7 @@ static void set_string(Object *obj, Visitor *v, const char *name,
         return;
     }
 
-    if (!visit_type_str(v, name, &str, &local_err)) {
-        error_propagate(errp, local_err);
+    if (!visit_type_str(v, name, &str, errp)) {
         return;
     }
     g_free(*ptr);
@@ -528,7 +522,6 @@ static void set_mac(Object *obj, Visitor *v, const char *name, void *opaque,
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
     MACAddr *mac = qdev_get_prop_ptr(dev, prop);
-    Error *local_err = NULL;
     int i, pos;
     char *str, *p;
 
@@ -537,8 +530,7 @@ static void set_mac(Object *obj, Visitor *v, const char *name, void *opaque,
         return;
     }
 
-    if (!visit_type_str(v, name, &str, &local_err)) {
-        error_propagate(errp, local_err);
+    if (!visit_type_str(v, name, &str, errp)) {
         return;
     }
 
@@ -832,15 +824,13 @@ static void set_size32(Object *obj, Visitor *v, const char *name, void *opaque,
     Property *prop = opaque;
     uint32_t *ptr = qdev_get_prop_ptr(dev, prop);
     uint64_t value;
-    Error *local_err = NULL;
 
     if (dev->realized) {
         qdev_prop_set_after_realize(dev, name, errp);
         return;
     }
 
-    if (!visit_type_size(v, name, &value, &local_err)) {
-        error_propagate(errp, local_err);
+    if (!visit_type_size(v, name, &value, errp)) {
         return;
     }
 
@@ -881,15 +871,13 @@ static void set_blocksize(Object *obj, Visitor *v, const char *name,
     Property *prop = opaque;
     uint32_t *ptr = qdev_get_prop_ptr(dev, prop);
     uint64_t value;
-    Error *local_err = NULL;
 
     if (dev->realized) {
         qdev_prop_set_after_realize(dev, name, errp);
         return;
     }
 
-    if (!visit_type_size(v, name, &value, &local_err)) {
-        error_propagate(errp, local_err);
+    if (!visit_type_size(v, name, &value, errp)) {
         return;
     }
     /* value of 0 means "unset" */
@@ -957,7 +945,6 @@ static void set_pci_host_devaddr(Object *obj, Visitor *v, const char *name,
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
     PCIHostDeviceAddress *addr = qdev_get_prop_ptr(dev, prop);
-    Error *local_err = NULL;
     char *str, *p;
     char *e;
     unsigned long val;
@@ -969,8 +956,7 @@ static void set_pci_host_devaddr(Object *obj, Visitor *v, const char *name,
         return;
     }
 
-    if (!visit_type_str(v, name, &str, &local_err)) {
-        error_propagate(errp, local_err);
+    if (!visit_type_str(v, name, &str, errp)) {
         return;
     }
 
@@ -1060,7 +1046,6 @@ static void set_uuid(Object *obj, Visitor *v, const char *name, void *opaque,
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
     QemuUUID *uuid = qdev_get_prop_ptr(dev, prop);
-    Error *local_err = NULL;
     char *str;
 
     if (dev->realized) {
@@ -1068,8 +1053,7 @@ static void set_uuid(Object *obj, Visitor *v, const char *name, void *opaque,
         return;
     }
 
-    if (!visit_type_str(v, name, &str, &local_err)) {
-        error_propagate(errp, local_err);
+    if (!visit_type_str(v, name, &str, errp)) {
         return;
     }
 
@@ -1135,7 +1119,6 @@ static void set_prop_arraylen(Object *obj, Visitor *v, const char *name,
     Property *prop = opaque;
     uint32_t *alenptr = qdev_get_prop_ptr(dev, prop);
     void **arrayptr = (void *)dev + prop->arrayoffset;
-    Error *local_err = NULL;
     void *eltptr;
     const char *arrayname;
     int i;
@@ -1149,8 +1132,7 @@ static void set_prop_arraylen(Object *obj, Visitor *v, const char *name,
                    name);
         return;
     }
-    if (!visit_type_uint32(v, name, alenptr, &local_err)) {
-        error_propagate(errp, local_err);
+    if (!visit_type_uint32(v, name, alenptr, errp)) {
         return;
     }
     if (!*alenptr) {
@@ -1473,7 +1455,6 @@ static void set_prop_pcielinkspeed(Object *obj, Visitor *v, const char *name,
     Property *prop = opaque;
     PCIExpLinkSpeed *p = qdev_get_prop_ptr(dev, prop);
     int speed;
-    Error *local_err = NULL;
 
     if (dev->realized) {
         qdev_prop_set_after_realize(dev, name, errp);
@@ -1481,8 +1462,7 @@ static void set_prop_pcielinkspeed(Object *obj, Visitor *v, const char *name,
     }
 
     if (!visit_type_enum(v, prop->name, &speed, prop->info->enum_table,
-                         &local_err)) {
-        error_propagate(errp, local_err);
+                         errp)) {
         return;
     }
 
@@ -1561,7 +1541,6 @@ static void set_prop_pcielinkwidth(Object *obj, Visitor *v, const char *name,
     Property *prop = opaque;
     PCIExpLinkWidth *p = qdev_get_prop_ptr(dev, prop);
     int width;
-    Error *local_err = NULL;
 
     if (dev->realized) {
         qdev_prop_set_after_realize(dev, name, errp);
@@ -1569,8 +1548,7 @@ static void set_prop_pcielinkwidth(Object *obj, Visitor *v, const char *name,
     }
 
     if (!visit_type_enum(v, prop->name, &width, prop->info->enum_table,
-                         &local_err)) {
-        error_propagate(errp, local_err);
+                         errp)) {
         return;
     }