From: Stefano Brivio <sbrivio@redhat.com>
To: passt-dev@passt.top
Subject: [PATCH] tcp: Disable optimisations for tcp_hash()
Date: Wed, 22 Feb 2023 13:16:00 +0100 [thread overview]
Message-ID: <20230222121600.3802188-1-sbrivio@redhat.com> (raw)
I'm not sure if we're breaking some aliasing rule here, but with gcc
12.2.1 on x86_64 and -flto, the siphash_20b() call in tcp_hash()
doesn't see the connection address -- it gets all zeroes instead.
Fix this temporarily by disabling optimisations for this tcp_hash().
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
---
tcp.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/tcp.c b/tcp.c
index 81468d9..803c2c4 100644
--- a/tcp.c
+++ b/tcp.c
@@ -1185,6 +1185,9 @@ static int tcp_hash_match(const struct tcp_tap_conn *conn,
#if TCP_HASH_NOINLINE
__attribute__((__noinline__)) /* See comment in Makefile */
#endif
+__attribute__((optimize("O0"))) /* TODO: with -O2 and -flto on gcc 12.2,
+ * siphash_20b() doesn't see 'addr', why?
+ */
static unsigned int tcp_hash(const struct ctx *c, const union inany_addr *addr,
in_port_t tap_port, in_port_t sock_port)
{
--
@@ -1185,6 +1185,9 @@ static int tcp_hash_match(const struct tcp_tap_conn *conn,
#if TCP_HASH_NOINLINE
__attribute__((__noinline__)) /* See comment in Makefile */
#endif
+__attribute__((optimize("O0"))) /* TODO: with -O2 and -flto on gcc 12.2,
+ * siphash_20b() doesn't see 'addr', why?
+ */
static unsigned int tcp_hash(const struct ctx *c, const union inany_addr *addr,
in_port_t tap_port, in_port_t sock_port)
{
--
2.39.1
reply other threads:[~2023-02-22 12:16 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
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=20230222121600.3802188-1-sbrivio@redhat.com \
--to=sbrivio@redhat.com \
--cc=passt-dev@passt.top \
/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.
Code repositories for project(s) associated with this public inbox
https://passt.top/passt
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 IMAP folder(s).