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Re: [PATCH 2/4] nbd: silence maybe-uninitialized warnings
From: |
Eric Blake |
Subject: |
Re: [PATCH 2/4] nbd: silence maybe-uninitialized warnings |
Date: |
Wed, 30 Sep 2020 12:19:39 -0500 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 |
On 9/30/20 10:58 AM, Christian Borntraeger wrote:
> gcc 10 from Fedora 32 gives me:
>
> Compiling C object libblock.fa.p/nbd_server.c.o
> ../nbd/server.c: In function ‘nbd_co_client_start’:
> ../nbd/server.c:625:14: error: ‘namelen’ may be used uninitialized in this
> function [-Werror=maybe-uninitialized]
> 625 | rc = nbd_negotiate_send_info(client, NBD_INFO_NAME, namelen,
> name,
> |
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 626 | errp);
> | ~~~~~
> ../nbd/server.c:564:14: note: ‘namelen’ was declared here
> 564 | uint32_t namelen;
> | ^~~~~~~
> cc1: all warnings being treated as errors
>
> As I cannot see how this can happen, let uns silence the warning.
gcc is smart enough to see that nbd_opt_read_name(... &namelen), which
is the only use of namelen between declaration and use, does not always
initialize namelen; but fails to see we also exit this function early in
the same conditions when nbd_opt_read_name left namelen uninit. The
workaround is fine.
Reviewed-by: Eric Blake <eblake@redhat.com>
I'm happy for this to go in through the trivial tree, but I'll also
queue it on my NBD tree if that is ready first.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
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- [PATCH 0/4] assorted gcc 10/fedora32 compile warning fixes, Christian Borntraeger, 2020/09/30
- [PATCH 3/4] qemu-io-cmds: avoid gcc 10 warning, Christian Borntraeger, 2020/09/30
- [PATCH 4/4] virtiofsd: avoid false positive compiler warning, Christian Borntraeger, 2020/09/30
- [PATCH 1/4] vmdk: fix maybe uninitialized warnings, Christian Borntraeger, 2020/09/30
- [PATCH 2/4] nbd: silence maybe-uninitialized warnings, Christian Borntraeger, 2020/09/30
- Re: [PATCH 2/4] nbd: silence maybe-uninitialized warnings,
Eric Blake <=
- Re: [PATCH 0/4] assorted gcc 10/fedora32 compile warning fixes, no-reply, 2020/09/30