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error: Eliminate error_propagate() with Coccinelle, part 1

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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>
This commit is contained in:
Markus Armbruster 2020-07-07 18:06:02 +02:00
parent dcfe480544
commit 668f62ec62
114 changed files with 383 additions and 896 deletions
Download patch file Download diff file Expand all files Collapse all files

24
util/qemu-option.c
View file

@ -524,7 +524,6 @@ static bool opt_validate(QemuOpt *opt, bool *help_wanted,
Error **errp)
{
const QemuOptDesc *desc;
Error *local_err = NULL;
desc = find_desc_by_name(opt->opts->list->desc, opt->name);
if (!desc && !opts_accepts_any(opt->opts)) {
@ -536,8 +535,7 @@ static bool opt_validate(QemuOpt *opt, bool *help_wanted,
}
opt->desc = desc;
if (!qemu_opt_parse(opt, &local_err)) {
error_propagate(errp, local_err);
if (!qemu_opt_parse(opt, errp)) {
return false;
}
@ -908,7 +906,6 @@ static QemuOpts *opts_parse(QemuOptsList *list, const char *params,
const char *firstname;
char *id = opts_parse_id(params);
QemuOpts *opts;
Error *local_err = NULL;
assert(!permit_abbrev || list->implied_opt_name);
firstname = permit_abbrev ? list->implied_opt_name : NULL;
@ -921,16 +918,14 @@ static QemuOpts *opts_parse(QemuOptsList *list, const char *params,
* (if unlikely) future misuse:
*/
assert(!defaults || list->merge_lists);
opts = qemu_opts_create(list, id, !defaults, &local_err);
opts = qemu_opts_create(list, id, !defaults, errp);
g_free(id);
if (opts == NULL) {
error_propagate(errp, local_err);
return NULL;
}
if (!opts_do_parse(opts, params, firstname, defaults, help_wanted,
&local_err)) {
error_propagate(errp, local_err);
errp)) {
qemu_opts_del(opts);
return NULL;
}
@ -1030,7 +1025,6 @@ static bool qemu_opts_from_qdict_entry(QemuOpts *opts,
QemuOpts *qemu_opts_from_qdict(QemuOptsList *list, const QDict *qdict,
Error **errp)
{
Error *local_err = NULL;
QemuOpts *opts;
const QDictEntry *entry;
@ -1044,8 +1038,7 @@ QemuOpts *qemu_opts_from_qdict(QemuOptsList *list, const QDict *qdict,
for (entry = qdict_first(qdict);
entry;
entry = qdict_next(qdict, entry)) {
if (!qemu_opts_from_qdict_entry(opts, entry, &local_err)) {
error_propagate(errp, local_err);
if (!qemu_opts_from_qdict_entry(opts, entry, errp)) {
qemu_opts_del(opts);
return NULL;
}
@ -1066,13 +1059,10 @@ bool qemu_opts_absorb_qdict(QemuOpts *opts, QDict *qdict, Error **errp)
entry = qdict_first(qdict);
while (entry != NULL) {
Error *local_err = NULL;
next = qdict_next(qdict, entry);
if (find_desc_by_name(opts->list->desc, entry->key)) {
if (!qemu_opts_from_qdict_entry(opts, entry, &local_err)) {
error_propagate(errp, local_err);
if (!qemu_opts_from_qdict_entry(opts, entry, errp)) {
return false;
}
qdict_del(qdict, entry->key);
@ -1144,7 +1134,6 @@ QDict *qemu_opts_to_qdict(QemuOpts *opts, QDict *qdict)
bool qemu_opts_validate(QemuOpts *opts, const QemuOptDesc *desc, Error **errp)
{
QemuOpt *opt;
Error *local_err = NULL;
assert(opts_accepts_any(opts));
@ -1155,8 +1144,7 @@ bool qemu_opts_validate(QemuOpts *opts, const QemuOptDesc *desc, Error **errp)
return false;
}
if (!qemu_opt_parse(opt, &local_err)) {
error_propagate(errp, local_err);
if (!qemu_opt_parse(opt, errp)) {
return false;
}
}