mirror_qemu/qapi
Markus Armbruster 668f62ec62 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>
2020-07-10 15:18:08 +02:00
..
Makefile.objs qemu-storage-daemon: Add --monitor option 2020-03-06 17:21:28 +01:00
audio.json audio/jack: add JACK client audiodev 2020-05-25 11:30:03 +02:00
authz.json authz: add QAuthZList object type for an access control list 2019-02-26 15:32:18 +00:00
block-core.json block/qcow2: implement blockdev-amend 2020-07-06 08:49:28 +02:00
block.json qapi: Mark deprecated QMP parts with feature 'deprecated' 2020-03-17 21:43:12 +01:00
char.json qapi: Belatedly update doc comment for @wait deprecation 2020-03-17 19:58:34 +01:00
common.json qapi: Move query-target from misc.json to machine.json 2019-08-21 13:24:01 +02:00
control.json qapi: Mark deprecated QMP parts with feature 'deprecated' 2020-03-17 21:43:12 +01:00
crypto.json qcrypto/luks: implement encryption key management 2020-07-06 08:49:28 +02:00
dump.json qapi: Fix indent level on doc comments in json files 2020-02-15 11:41:50 +01:00
error.json qapi: Split error.json off common.json 2019-08-16 13:31:51 +02:00
introspect.json qapi: Add feature flags to struct members 2020-03-17 21:25:47 +01:00
job.json block/core: add generic infrastructure for x-blockdev-amend qmp command 2020-07-06 08:49:28 +02:00
machine-target.json qapi: Fix indent level on doc comments in json files 2020-02-15 11:41:50 +01:00
machine.json Add rx-softmmu 2020-03-19 17:58:05 +01:00
migration.json migration/xbzrle: add encoding rate 2020-05-07 17:40:24 +01:00
misc-target.json qapi: Fix indent level on doc comments in json files 2020-02-15 11:41:50 +01:00
misc.json virtio-pci: Send qapi events when the virtio-mem size changes 2020-07-03 07:57:04 -04:00
net.json vhost-vdpa: introduce vhost-vdpa net client 2020-07-07 07:59:51 -04:00
opts-visitor.c qapi: Make visitor functions taking Error ** return bool, not void 2020-07-10 15:18:08 +02:00
pragma.json qapi: Create 'pragma' module 2020-03-06 17:21:28 +01:00
qapi-clone-visitor.c qapi: Make visitor functions taking Error ** return bool, not void 2020-07-10 15:18:08 +02:00
qapi-dealloc-visitor.c qapi: Make visitor functions taking Error ** return bool, not void 2020-07-10 15:18:08 +02:00
qapi-schema.json qapi: Create 'pragma' module 2020-03-06 17:21:28 +01:00
qapi-util.c qemu-common: Move qemu_isalnum() etc. to qemu/ctype.h 2019-06-11 20:22:09 +02:00
qapi-visit-core.c qapi: Make visitor functions taking Error ** return bool, not void 2020-07-10 15:18:08 +02:00
qdev.json qapi: Fix indent level on doc comments in json files 2020-02-15 11:41:50 +01:00
qmp-dispatch.c qmp: fix leak on callbacks that return both value and error 2020-04-02 14:55:46 -04:00
qmp-event.c Include qemu-common.h exactly where needed 2019-06-12 13:20:20 +02:00
qmp-registry.c qmp: constify QmpCommand and list 2020-03-17 21:43:12 +01:00
qobject-input-visitor.c qapi: Make visitor functions taking Error ** return bool, not void 2020-07-10 15:18:08 +02:00
qobject-output-visitor.c qapi: Make visitor functions taking Error ** return bool, not void 2020-07-10 15:18:08 +02:00
qom.json qapi: Flatten object-add 2020-03-06 17:21:27 +01:00
rdma.json qapi: Define new QMP message for pvrdma 2018-12-22 11:09:56 +02:00
rocker.json qapi: Fix indent level on doc comments in json files 2020-02-15 11:41:50 +01:00
run-state.json qapi: Fix indent level on doc comments in json files 2020-02-15 11:41:50 +01:00
sockets.json qemu-sockets: add abstract UNIX domain socket support 2020-05-20 10:34:40 +01:00
string-input-visitor.c error: Eliminate error_propagate() with Coccinelle, part 1 2020-07-10 15:18:08 +02:00
string-output-visitor.c qapi: Make visitor functions taking Error ** return bool, not void 2020-07-10 15:18:08 +02:00
tpm.json qapi: Use explicit bulleted lists 2020-02-15 11:41:50 +01:00
trace-events trace-events: Shorten file names in comments 2019-03-22 16:18:07 +00:00
trace.json qapi: Add blank lines before bulleted lists 2020-02-15 11:41:50 +01:00
transaction.json qemu-storage-daemon: Add --monitor option 2020-03-06 17:21:28 +01:00
ui.json qapi: Delete all the "foo: dropped in n.n" notes 2020-02-15 11:41:50 +01:00