From: "Morten Brørup" <mb@smartsharesystems.com>
To: "Tyler Retzlaff" <roretzla@linux.microsoft.com>, <dev@dpdk.org>
Cc: "Bruce Richardson" <bruce.richardson@intel.com>,
"Stephen Hemminger" <stephen@networkplumber.org>,
"Thomas Monjalon" <thomas@monjalon.net>
Subject: RE: [PATCH 3/4] vhost: use alloca instead of vla sizeof
Date: Sun, 7 Apr 2024 00:30:42 +0200 [thread overview]
Message-ID: <98CBD80474FA8B44BF855DF32C47DC35E9F377@smartserver.smartshare.dk> (raw)
In-Reply-To: <1712250913-1977-4-git-send-email-roretzla@linux.microsoft.com>
> From: Tyler Retzlaff [mailto:roretzla@linux.microsoft.com]
> Sent: Thursday, 4 April 2024 19.15
>
> RFC sample illustrating conversion of VLA to alloca() where
> sizeof(array) was in use.
>
> Signed-off-by: Tyler Retzlaff <roretzla@linux.microsoft.com>
> ---
> lib/vhost/socket.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/lib/vhost/socket.c b/lib/vhost/socket.c
> index 96b3ab5..cedcfb2 100644
> --- a/lib/vhost/socket.c
> +++ b/lib/vhost/socket.c
> @@ -110,7 +110,8 @@ struct vhost_user {
> {
> struct iovec iov;
> struct msghdr msgh;
> - char control[CMSG_SPACE(max_fds * sizeof(int))];
> + const size_t control_sz = sizeof(char) * CMSG_SPACE(max_fds *
> sizeof(int));
I get the point, but think multiplying with sizeof(char) is overkill.
It's a matter of personal taste; maybe it's just me.
If it was an array of a different type, e.g. int, multiplying with sizeof(int) would be required, like in the latencystats example.
Anyway, I agree with the approach here.
> + char *control = alloca(control_sz);
> struct cmsghdr *cmsg;
> int got_fds = 0;
> int ret;
> @@ -124,7 +125,7 @@ struct vhost_user {
> msgh.msg_iov = &iov;
> msgh.msg_iovlen = 1;
> msgh.msg_control = control;
> - msgh.msg_controllen = sizeof(control);
> + msgh.msg_controllen = control_sz;
>
> ret = recvmsg(sockfd, &msgh, 0);
> if (ret <= 0) {
> --
> 1.8.3.1
next prev parent reply other threads:[~2024-04-06 22:30 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-07 19:32 RFC acceptable handling of VLAs across toolchains Tyler Retzlaff
2023-11-08 2:31 ` Stephen Hemminger
2023-11-08 3:25 ` Tyler Retzlaff
2023-11-08 8:19 ` Morten Brørup
2023-11-08 16:51 ` Stephen Hemminger
2023-11-08 17:48 ` Morten Brørup
2023-11-09 10:25 ` RFC: default burst sizes in rte_config Morten Brørup
2023-11-09 20:26 ` RFC acceptable handling of VLAs across toolchains Tyler Retzlaff
2024-03-21 0:12 ` Tyler Retzlaff
2024-04-04 17:15 ` [PATCH 0/4] RFC samples converting VLA to alloca Tyler Retzlaff
2024-04-04 17:15 ` [PATCH 1/4] latencystats: use alloca instead of vla trivial Tyler Retzlaff
2024-04-06 15:28 ` Morten Brørup
2024-04-07 9:36 ` Mattias Rönnblom
2024-04-07 17:00 ` Stephen Hemminger
2024-04-04 17:15 ` [PATCH 2/4] hash: " Tyler Retzlaff
2024-04-06 16:01 ` Morten Brørup
2024-04-04 17:15 ` [PATCH 3/4] vhost: use alloca instead of vla sizeof Tyler Retzlaff
2024-04-06 22:30 ` Morten Brørup [this message]
2024-04-04 17:15 ` [PATCH 4/4] dispatcher: use alloca instead of vla multi dimensional Tyler Retzlaff
2024-04-06 15:49 ` Morten Brørup
2024-04-07 9:31 ` [PATCH 0/4] RFC samples converting VLA to alloca Mattias Rönnblom
2024-04-07 11:07 ` Morten Brørup
2024-04-07 17:03 ` Stephen Hemminger
2024-04-08 15:27 ` Tyler Retzlaff
2024-04-08 15:53 ` Morten Brørup
2024-04-09 8:28 ` Konstantin Ananyev
2024-04-09 15:08 ` Tyler Retzlaff
2024-04-10 9:58 ` Konstantin Ananyev
2024-04-10 17:03 ` Tyler Retzlaff
2024-04-10 7:32 ` Mattias Rönnblom
2024-04-10 7:52 ` Morten Brørup
2024-04-10 17:04 ` Tyler Retzlaff
2024-04-10 7:27 ` Mattias Rönnblom
2024-04-10 17:10 ` Tyler Retzlaff
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