qemu-e2k/hw/virtio
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
..
Kconfig virtio-mem: Paravirtualized memory hot(un)plug 2020-07-03 07:57:04 -04:00
Makefile.objs vhost-vdpa: introduce vhost-vdpa backend 2020-07-07 07:59:51 -04:00
trace-events virtio,acpi: features, fixes, cleanups. 2020-07-07 17:37:44 +01:00
vhost-backend.c vhost-vdpa: introduce vhost-vdpa backend 2020-07-07 07:59:51 -04:00
vhost-scsi-pci.c qdev: Convert uses of qdev_set_parent_bus() with Coccinelle 2020-06-15 22:05:08 +02:00
vhost-stub.c
vhost-user-blk-pci.c qdev: Convert uses of qdev_set_parent_bus() with Coccinelle 2020-06-15 22:05:08 +02:00
vhost-user-fs-pci.c qdev: Convert uses of qdev_set_parent_bus() with Coccinelle 2020-06-15 22:05:08 +02:00
vhost-user-fs.c qdev: Unrealize must not fail 2020-05-15 07:08:14 +02:00
vhost-user-input-pci.c
vhost-user-scsi-pci.c qdev: Convert uses of qdev_set_parent_bus() with Coccinelle 2020-06-15 22:05:08 +02:00
vhost-user-vsock-pci.c qdev: Convert uses of qdev_set_parent_bus() with Coccinelle 2020-06-15 22:05:08 +02:00
vhost-user-vsock.c virtio: add vhost-user-vsock base device 2020-06-12 10:17:06 -04:00
vhost-user.c Stop vhost-user sending uninitialized mmap_offsets 2020-06-24 17:18:28 -04:00
vhost-vdpa.c vhost-vdpa: introduce vhost-vdpa backend 2020-07-07 07:59:51 -04:00
vhost-vsock-common.c vhost-vsock: add vhost-vsock-common abstraction 2020-06-12 10:17:06 -04:00
vhost-vsock-pci.c qdev: Convert uses of qdev_set_parent_bus() with Coccinelle 2020-06-15 22:05:08 +02:00
vhost-vsock.c vhost-vsock: add vhost-vsock-common abstraction 2020-06-12 10:17:06 -04:00
vhost.c vhost: implement vhost_force_iommu method 2020-07-03 07:57:04 -04:00
virtio-9p-pci.c qdev: Convert uses of qdev_set_parent_bus() with Coccinelle 2020-06-15 22:05:08 +02:00
virtio-balloon-pci.c qdev: Convert uses of qdev_set_parent_bus() with Coccinelle 2020-06-15 22:05:08 +02:00
virtio-balloon.c error: Eliminate error_propagate() with Coccinelle, part 1 2020-07-10 15:18:08 +02:00
virtio-blk-pci.c qdev: Convert uses of qdev_set_parent_bus() with Coccinelle 2020-06-15 22:05:08 +02:00
virtio-bus.c
virtio-crypto-pci.c qom: Put name parameter before value / visitor parameter 2020-07-10 15:18:08 +02:00
virtio-crypto.c qdev: Unrealize must not fail 2020-05-15 07:08:14 +02:00
virtio-input-host-pci.c
virtio-input-pci.c qdev: Convert uses of qdev_set_parent_bus() with Coccinelle 2020-06-15 22:05:08 +02:00
virtio-iommu-pci.c qom: Put name parameter before value / visitor parameter 2020-07-10 15:18:08 +02:00
virtio-iommu.c virtio-iommu: Handle reserved regions in the translation process 2020-07-03 16:59:42 +01:00
virtio-mem-pci.c qom: Put name parameter before value / visitor parameter 2020-07-10 15:18:08 +02:00
virtio-mem-pci.h virtio-pci: Send qapi events when the virtio-mem size changes 2020-07-03 07:57:04 -04:00
virtio-mem.c virtio-mem: Exclude unplugged memory during migration 2020-07-03 07:57:04 -04:00
virtio-mmio.c
virtio-net-pci.c qdev: Convert uses of qdev_set_parent_bus() with Coccinelle 2020-06-15 22:05:08 +02:00
virtio-pci.c virtio-pci: implement queue_enabled method 2020-07-03 07:57:04 -04:00
virtio-pci.h
virtio-pmem-pci.c qom: Put name parameter before value / visitor parameter 2020-07-10 15:18:08 +02:00
virtio-pmem-pci.h
virtio-pmem.c qdev: Unrealize must not fail 2020-05-15 07:08:14 +02:00
virtio-rng-pci.c error: Eliminate error_propagate() with Coccinelle, part 1 2020-07-10 15:18:08 +02:00
virtio-rng.c error: Eliminate error_propagate() with Coccinelle, part 1 2020-07-10 15:18:08 +02:00
virtio-scsi-pci.c qdev: Convert uses of qdev_set_parent_bus() with Coccinelle 2020-06-15 22:05:08 +02:00
virtio-serial-pci.c qdev: Convert uses of qdev_set_parent_bus() with Coccinelle 2020-06-15 22:05:08 +02:00
virtio.c virtio-bus: introduce queue_enabled method 2020-07-03 07:57:04 -04:00