qemu-devel.nongnu.org archive mirror
 help / color / mirror / Atom feed
From: Stefan Hajnoczi <stefanha@gmail.com>
To: Max Reitz <mreitz@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>,
	Paolo Bonzini <pbonzini@redhat.com>, Fam Zheng <famz@redhat.com>,
	qemu-devel@nongnu.org, Stefan Hajnoczi <stefanha@redhat.com>
Subject: Re: [Qemu-devel] [RFC 1/5] nbd: Correct name comparison for export_set_name()
Date: Wed, 4 Jun 2014 13:52:46 +0200	[thread overview]
Message-ID: <20140604115246.GB11073@stefanha-thinkpad.redhat.com> (raw)
In-Reply-To: <1401561792-13410-2-git-send-email-mreitz@redhat.com>

On Sat, May 31, 2014 at 08:43:08PM +0200, Max Reitz wrote:
> exp->name == name is certainly true if both strings are equal and will
> work for both of them being NULL (which is important to check here);
> however, the strings may also be equal without having the same address,
> in which case there is no need to replace the export's name either.
> Therefore, add a check for this case.
> 
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>  nbd.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/nbd.c b/nbd.c
> index e5084b6..0787cba 100644
> --- a/nbd.c
> +++ b/nbd.c
> @@ -832,7 +832,7 @@ NBDExport *nbd_export_find(const char *name)
>  
>  void nbd_export_set_name(NBDExport *exp, const char *name)
>  {
> -    if (exp->name == name) {
> +    if (exp->name == name || (exp->name && name && !strcmp(exp->name, name))) {
>          return;
>      }

It's not clear to me why we even bother.  The function is idempotent and
there are only 2 call sites in QEMU.  This is not a performance-critical
function where it helps to bail early.

Can we just drop the if statement completely?

void nbd_export_set_name(NBDExport *exp, const char *name)
{
    if (exp->name == name) {
        return;
    }

    nbd_export_get(exp);
    if (exp->name != NULL) {
        g_free(exp->name);
        exp->name = NULL;
        QTAILQ_REMOVE(&exports, exp, next);
        nbd_export_put(exp);
    }
    if (name != NULL) {
        nbd_export_get(exp);
        exp->name = g_strdup(name);
        QTAILQ_INSERT_TAIL(&exports, exp, next);
    }
    nbd_export_put(exp);
}

  parent reply	other threads:[~2014-06-04 11:53 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <1401561792-13410-1-git-send-email-mreitz@redhat.com>
2014-06-03 14:38 ` [Qemu-devel] [RFC 0/5] nbd: Adapt for dataplane Stefan Hajnoczi
2014-06-05 17:41   ` Max Reitz
     [not found] ` <1401561792-13410-3-git-send-email-mreitz@redhat.com>
2014-06-03 17:55   ` [Qemu-devel] [RFC 2/5] aio: Add io_read_poll() callback Paolo Bonzini
2014-06-05 17:29     ` Max Reitz
2014-06-04 11:59   ` Stefan Hajnoczi
     [not found] ` <1401561792-13410-2-git-send-email-mreitz@redhat.com>
2014-06-04 11:52   ` Stefan Hajnoczi [this message]
2014-06-05 17:28     ` [Qemu-devel] [RFC 1/5] nbd: Correct name comparison for export_set_name() Max Reitz
     [not found] ` <1401561792-13410-4-git-send-email-mreitz@redhat.com>
2014-06-04 12:37   ` [Qemu-devel] [RFC 3/5] nbd: Use aio_set_fd_handler2() Stefan Hajnoczi
2014-06-04 18:02     ` Paolo Bonzini
2014-06-05  8:12       ` Stefan Hajnoczi
2014-06-05  9:27         ` Paolo Bonzini
2014-06-05 13:32           ` Stefan Hajnoczi
2014-06-05 18:18     ` Max Reitz
2014-06-06  7:44       ` Paolo Bonzini
2014-06-07 19:27         ` Max Reitz
2014-06-09 13:35           ` Stefan Hajnoczi
     [not found] ` <1401561792-13410-5-git-send-email-mreitz@redhat.com>
2014-06-04 12:41   ` [Qemu-devel] [RFC 4/5] block: Add AIO followers Stefan Hajnoczi
2014-06-05 17:31     ` Max Reitz
     [not found] ` <538A3A8F.3060508@redhat.com>
2014-06-04 12:47   ` [Qemu-devel] [RFC 0/5] nbd: Adapt for dataplane Stefan Hajnoczi
2014-06-04 12:50 ` Stefan Hajnoczi

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20140604115246.GB11073@stefanha-thinkpad.redhat.com \
    --to=stefanha@gmail.com \
    --cc=famz@redhat.com \
    --cc=kwolf@redhat.com \
    --cc=mreitz@redhat.com \
    --cc=pbonzini@redhat.com \
    --cc=qemu-devel@nongnu.org \
    --cc=stefanha@redhat.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).