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>

9 files changed, 10 insertions, 24 deletions

diff --git a/block/curl.c b/block/curl.c
index d9552efe52..4f907c47be 100644
--- a/block/curl.c
+++ b/block/curl.c
@@ -669,7 +669,6 @@ static int curl_open(BlockDriverState *bs, QDict *options, int flags,
     BDRVCURLState *s = bs->opaque;
     CURLState *state = NULL;
     QemuOpts *opts;
-    Error *local_err = NULL;
     const char *file;
     const char *cookie;
     const char *cookie_secret;
@@ -695,8 +694,7 @@ static int curl_open(BlockDriverState *bs, QDict *options, int flags,
 
     qemu_mutex_init(&s->mutex);
     opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort);
-    if (!qemu_opts_absorb_qdict(opts, options, &local_err)) {
-        error_propagate(errp, local_err);
+    if (!qemu_opts_absorb_qdict(opts, options, errp)) {
         goto out_noclean;
     }
 
diff --git a/block/file-posix.c b/block/file-posix.c
index 36acf7b911..b35ea99d42 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -3331,7 +3331,6 @@ static int hdev_open(BlockDriverState *bs, QDict *options, int flags,
                      Error **errp)
 {
     BDRVRawState *s = bs->opaque;
-    Error *local_err = NULL;
     int ret;
 
 #if defined(__APPLE__) && defined(__MACH__)
@@ -3396,9 +3395,8 @@ hdev_open_Mac_error:
 
     s->type = FTYPE_FILE;
 
-    ret = raw_open_common(bs, options, flags, 0, true, &local_err);
+    ret = raw_open_common(bs, options, flags, 0, true, errp);
     if (ret < 0) {
-        error_propagate(errp, local_err);
 #if defined(__APPLE__) && defined(__MACH__)
         if (*bsd_path) {
             filename = bsd_path;
@@ -3674,14 +3672,12 @@ static int cdrom_open(BlockDriverState *bs, QDict *options, int flags,
                       Error **errp)
 {
     BDRVRawState *s = bs->opaque;
-    Error *local_err = NULL;
     int ret;
 
     s->type = FTYPE_CD;
 
-    ret = raw_open_common(bs, options, flags, 0, true, &local_err);
+    ret = raw_open_common(bs, options, flags, 0, true, errp);
     if (ret) {
-        error_propagate(errp, local_err);
         return ret;
     }
 
diff --git a/block/parallels.c b/block/parallels.c
index 32d0ecd398..ff27a85c01 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -646,9 +646,8 @@ static int coroutine_fn parallels_co_create_opts(BlockDriver *drv,
     }
 
     /* Create and open the file (protocol layer) */
-    ret = bdrv_create_file(filename, opts, &local_err);
+    ret = bdrv_create_file(filename, opts, errp);
     if (ret < 0) {
-        error_propagate(errp, local_err);
         goto done;
     }
 
diff --git a/block/qcow.c b/block/qcow.c
index ee5d35fe20..dca2a1fe7d 100644
--- a/block/qcow.c
+++ b/block/qcow.c
@@ -973,9 +973,8 @@ static int coroutine_fn qcow_co_create_opts(BlockDriver *drv,
     }
 
     /* Create and open the file (protocol layer) */
-    ret = bdrv_create_file(filename, opts, &local_err);
+    ret = bdrv_create_file(filename, opts, errp);
     if (ret < 0) {
-        error_propagate(errp, local_err);
         goto fail;
     }
 
diff --git a/block/qed.c b/block/qed.c
index ece8b9bb60..e04b7ab5f0 100644
--- a/block/qed.c
+++ b/block/qed.c
@@ -749,9 +749,8 @@ static int coroutine_fn bdrv_qed_co_create_opts(BlockDriver *drv,
     }
 
     /* Create and open the file (protocol layer) */
-    ret = bdrv_create_file(filename, opts, &local_err);
+    ret = bdrv_create_file(filename, opts, errp);
     if (ret < 0) {
-        error_propagate(errp, local_err);
         goto fail;
     }
 
diff --git a/block/throttle-groups.c b/block/throttle-groups.c
index 3d7e7cf990..03a53c89ea 100644
--- a/block/throttle-groups.c
+++ b/block/throttle-groups.c
@@ -811,7 +811,6 @@ static void throttle_group_set(Object *obj, Visitor *v, const char * name,
     ThrottleGroup *tg = THROTTLE_GROUP(obj);
     ThrottleConfig *cfg;
     ThrottleParamInfo *info = opaque;
-    Error *local_err = NULL;
     int64_t value;
 
     /* If we have finished initialization, don't accept individual property
@@ -823,8 +822,7 @@ static void throttle_group_set(Object *obj, Visitor *v, const char * name,
         return;
     }
 
-    if (!visit_type_int64(v, name, &value, &local_err)) {
-        error_propagate(errp, local_err);
+    if (!visit_type_int64(v, name, &value, errp)) {
         return;
     }
     if (value < 0) {
diff --git a/block/vhdx.c b/block/vhdx.c
index 645dc4b4f4..327675cc7c 100644
--- a/block/vhdx.c
+++ b/block/vhdx.c
@@ -2083,9 +2083,8 @@ static int coroutine_fn vhdx_co_create_opts(BlockDriver *drv,
     }
 
     /* Create and open the file (protocol layer) */
-    ret = bdrv_create_file(filename, opts, &local_err);
+    ret = bdrv_create_file(filename, opts, errp);
     if (ret < 0) {
-        error_propagate(errp, local_err);
         goto fail;
     }
 
diff --git a/block/vmdk.c b/block/vmdk.c
index 62da465126..4d42d2fbe1 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -2252,9 +2252,8 @@ static int vmdk_create_extent(const char *filename, int64_t filesize,
     BlockBackend *blk = NULL;
     Error *local_err = NULL;
 
-    ret = bdrv_create_file(filename, opts, &local_err);
+    ret = bdrv_create_file(filename, opts, errp);
     if (ret < 0) {
-        error_propagate(errp, local_err);
         goto exit;
     }
 
diff --git a/block/vpc.c b/block/vpc.c
index 119350d495..04da71e9e6 100644
--- a/block/vpc.c
+++ b/block/vpc.c
@@ -1113,9 +1113,8 @@ static int coroutine_fn vpc_co_create_opts(BlockDriver *drv,
     }
 
     /* Create and open the file (protocol layer) */
-    ret = bdrv_create_file(filename, opts, &local_err);
+    ret = bdrv_create_file(filename, opts, errp);
     if (ret < 0) {
-        error_propagate(errp, local_err);
         goto fail;
     }