From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from jabberwock.ucw.cz (jabberwock.ucw.cz [46.255.230.98]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7B8D6364DA; Thu, 28 Mar 2024 10:35:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=46.255.230.98 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711622120; cv=none; b=ia5CdBHPUw2QnQnmR4jo0NDoXQC56e5YQR4mADsUDxC8e5fJtKmctTbq+uQpop+wyyCqPN9GPrUg85uRwfxqpPAefVhaW21WRU+YsJnPVnRwFOgl8Vreiosr3sDVAfZRMvMUyEsuNgyMPrE+1Vmh0AnggFFxUAcYjtAtdBbq5B0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711622120; c=relaxed/simple; bh=7vFSQ747FM06KN1wrNfHC48TjsBeAGoEHNFZdXAOOxM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=TRKtlYrwq0HZPE4ZfDnifoG6jYgGUgknRaLIOyQTR0mxTHogSA1XFMrkeQCPOpXMXJBqJ8dDZFRArHSwDtko5pdc+VvuaIsjRiqkCJwLnyEicXni1ED+lXuJUhkgxyp4dFuY+toTGn2BkMenLqMe7GMKWG4yFsBh0m8OZb3U9F0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=denx.de; spf=fail smtp.mailfrom=denx.de; arc=none smtp.client-ip=46.255.230.98 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=denx.de Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=denx.de Received: by jabberwock.ucw.cz (Postfix, from userid 1017) id B1D141C0081; Thu, 28 Mar 2024 11:35:16 +0100 (CET) Date: Thu, 28 Mar 2024 11:35:16 +0100 From: Pavel Machek To: Sasha Levin Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, Eric Dumazet , Taehee Yoo , Cong Wang , David Ahern , "David S . Miller" Subject: Re: [PATCH 6.1 140/451] ipv6: mcast: remove one synchronize_net() barrier in ipv6_mc_down() Message-ID: References: <20240324231207.1351418-1-sashal@kernel.org> <20240324231207.1351418-141-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="jR9q48rvjneaP0k+" Content-Disposition: inline In-Reply-To: <20240324231207.1351418-141-sashal@kernel.org> --jR9q48rvjneaP0k+ Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi! > From: Eric Dumazet >=20 > [ Upstream commit 17ef8efc00b34918b966388b2af0993811895a8c ] >=20 > As discussed in the past (commit 2d3916f31891 ("ipv6: fix skb drops > in igmp6_event_query() and igmp6_event_report()")) I think the > synchronize_net() call in ipv6_mc_down() is not needed. >=20 > Under load, synchronize_net() can last between 200 usec and 5 ms. >=20 > KASAN seems to agree as well. This is performance tweak, not a bugfix. We probably should not have it in stable. Best regards, Pavel > diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c > index 566f3b7b957e9..a777695389403 100644 > --- a/net/ipv6/mcast.c > +++ b/net/ipv6/mcast.c > @@ -2722,7 +2722,6 @@ void ipv6_mc_down(struct inet6_dev *idev) > /* Should stop work after group drop. or we will > * start work again in mld_ifc_event() > */ > - synchronize_net(); > mld_query_stop_work(idev); > mld_report_stop_work(idev); > =20 --=20 DENX Software Engineering GmbH, Managing Director: Erika Unter HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany --jR9q48rvjneaP0k+ Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iF0EABECAB0WIQRPfPO7r0eAhk010v0w5/Bqldv68gUCZgVH5AAKCRAw5/Bqldv6 8uwFAJ4jiqh3X7yU1KwHULt+PeY5XCqq7QCfSPZ1HLmE8WjWvaJvbb6vDYMqS6Y= =Ft3s -----END PGP SIGNATURE----- --jR9q48rvjneaP0k+--