Re: [PATCH v2 35/44] error: Eliminate error_propagate() with Coccinelle, part 2

[Markus Armbruster]

Eric Blake <eblake@redhat.com> writes:

> On 7/2/20 10:49 AM, Markus Armbruster wrote:
>> 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.  The previous commit did that with a Coccinelle script I
>> consider fairly trustworthy.  This commit uses the same script with
>> the matching of return taken out, i.e. we convert
>>
>>      if (!foo(..., &err)) {
>>      ...
>>      error_propagate(errp, err);
>>      ...
>>      }
>>
>> to
>>
>>      if (!foo(..., errp)) {
>>      ...
>>      ...
>>      }
>>
>> This is unsound: @err could still be read between afterwards.  I don't
>> know how to express "no read of @err without an intervening write" in
>> Coccinelle.  Instead, I manually double-checked for uses of @err.
>>
>> Suboptimal line breaks tweaked manually.  qdev_realize() simplified
>> further to placate scripts/checkpatch.pl.
>>
>> Signed-off-by: Markus Armbruster <armbru@redhat.com>
>> ---
>>   block.c              |  6 ++----
>>   block/blkdebug.c     |  7 ++-----
>>   block/blklogwrites.c |  3 +--
>>   block/blkverify.c    |  3 +--
>>   block/crypto.c       |  4 +---
>>   block/file-posix.c   |  6 ++----
>>   block/file-win32.c   |  6 ++----
>>   block/gluster.c      |  4 +---
>>   block/iscsi.c        |  3 +--
>>   block/nbd.c          |  8 ++------
>>   block/qcow2.c        | 13 ++++---------
>>   block/raw-format.c   |  4 +---
>>   block/sheepdog.c     |  8 ++------
>>   block/ssh.c          |  4 +---
>>   block/throttle.c     |  4 +---
>>   block/vmdk.c         |  4 +---
>>   block/vpc.c          |  3 +--
>>   block/vvfat.c        |  3 +--
>>   blockdev.c           |  3 +--
>>   hw/intc/xics.c       |  4 +---
>>   hw/vfio/pci.c        |  3 +--
>>   net/tap.c            |  3 +--
>>   qom/object.c         |  4 +---
>>   23 files changed, 32 insertions(+), 78 deletions(-)
>
> Small enough to review each instance.
>
> Reviewed-by: Eric Blake <eblake@redhat.com>

I tried *really* hard to make part 1's script powerful and safe, to give
the unsafe / manual parts (this commit and next) a chance of meaningful
review.  Thanks for providing it!