From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 C4831395AF6 for ; Tue, 21 Jul 2026 15:12:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784646762; cv=none; b=GoWquQtBJgRFoxtTPf2IBk2uB7smdgAqYHWf5We5OCUsYdLspasWsmruaOgKP/wlnBZN5YffPZDbUWZb5WXn0h/j3h00e85S8VUORZbDB/NRM++3I2ok3Ihr/qY/CVl6dGU4XHMTX7xPDg3Sh/W9El0m/2o+0BAF47duhTn0h1g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784646762; c=relaxed/simple; bh=K+Fn/zS+yilIxwqRj4xxL03genFT4FwfCOTQvQKYjQo=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=rCyxtqGN+OGSUgzgQ4iljD+Bq9ySsLNLavmRZt2SP6RiWX6Uj+Wpz2MfCAy0sXAQcLo/5mA2/IaVoZePDKzShBApYcGlQDeEJNHK7iKDsw9oob3lpo4NNEALA6brTKQdpzaIa3EuTLS74Bk+Muz4JY3SDBQBiFaUQUkUVGtvFvw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Zta5yEPX; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Zta5yEPX" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6F3571F00A3D; Tue, 21 Jul 2026 15:12:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784646761; bh=TIAUQwc98Z9ARw9IDAG2umdiqvpOuJyHvbfgbIxRls0=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=Zta5yEPXc3GSz0gTgFXXcKL783EwKkRjTJaTHkdFUF14vsWKOD7yOBHqUeEoOVMFd UYmsUSWz+xAuN5yl2r9hl350MCKodurztzlUHgQ3nwyj2Kq2jb+Xl9oQs2FdHCTed9 AAjkcguGYvr73kAGOdgyWNruM3YeKPe0vPwoYU9dZvbp5q0/4zh48JCIAsrDG+ej9b uy57EMFp+IZfQris7hZ6eNK6F7f5XVlTdK2pLGLXOXyieNO3rmYNYYh0oyydsjMCGK pRDLxvqLmUi9AkH0TjdcMtkUsZ4KoOgypKNLYT5vd2UHhxW3oMcD8WU3s7O/+oRCtN +FLRRxzTbkW0g== Date: Tue, 21 Jul 2026 08:12:40 -0700 From: Jakub Kicinski To: Paolo Abeni Cc: Emil Tsalapatis , netdev@vger.kernel.org, edumazet@google.com, ncardwell@google.com, kuniyu@google.com, davem@davemloft.net Subject: Re: [PATCH net-next] net/tcp: Prevent inlining tcp_syn_ack_timeout() Message-ID: <20260721081240.1b88db50@kernel.org> In-Reply-To: <6c01c713-14a8-43c2-aaaf-2fcf622f7e4f@redhat.com> References: <20260708180837.9507-1-emil@etsalapatis.com> <6c01c713-14a8-43c2-aaaf-2fcf622f7e4f@redhat.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Tue, 21 Jul 2026 15:24:52 +0200 Paolo Abeni wrote: > On 7/8/26 8:08 PM, Emil Tsalapatis wrote: > > The tcp_syn_ack_timeout() function gets inlined by Clang, > > preventing tracing. Since the call is not in the fast > > path, prevent it from being inlined. > > > > Signed-off-by: Emil Tsalapatis > > --- > > net/ipv4/tcp_timer.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c > > index bf171b5e1eb3..f7215d53bbda 100644 > > --- a/net/ipv4/tcp_timer.c > > +++ b/net/ipv4/tcp_timer.c > > @@ -748,7 +748,7 @@ static void tcp_write_timer(struct timer_list *t) > > sock_put(sk); > > } > > > > -void tcp_syn_ack_timeout(const struct request_sock *req) > > +noinline_for_tracing void tcp_syn_ack_timeout(const struct request_sock *req) > > { > > struct net *net = read_pnet(&inet_rsk(req)->ireq_net); > > > > What's the point of tracing such function? It just increment a mib. If > you want to discriminate between TFO and non TFO syn ack timeout, > possibly adding another MIB counter and incrementing it in > tcp_fastopen_synack_timer() would be better??? FWIW we seem to capture the 5 tuple when it happens, not just mib counter. Internal commit (form 2019) just says we want to know when syn-ack is blackholed, unclear under what conditions this happens.