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);
}
next prev 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
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