From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=95.215.58.113 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793755942; b=2eOmI+BfGl3j5KiaIEZzlrxR/pKeg6SfN/kRoacZ4hGaQBH0pYseggH10o7cKK3eXART eU6zdHeAV9cnrmpTsARB2JTMjtfbQY6T7z/NwnRVBn16dMYLw6VjTMv9tbaTZfUtZ5jVi mV29Vu63YaPUN0iHCKkWHklaOneeqdhZBiHW5MOWX/1NEIQV3kFy5+RWJuNPU6Adue2kC DKzbGL0kcDaBaZALvpZg8YJghgaxvpUMJQeqh0N8OuhEMu1e3AyE0SnGEHEwSjzGUim8/ wH18+Z3mp2JVBZmq+ikLGmGquRqh4s+pq73VhhDMGTzyvM9+rUN9pVtGE3Y5b6qB4Rw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793755942; h=DMARC-Filter:X-Envelope-To:DKIM-Signature:X-Envelope-To:Received: X-Mizu-Trace-ID:X-Migadu-Flow:Message-ID:Date:MIME-Version:User-Agent: Subject:To:Cc:References:From:In-Reply-To:Content-Type: Content-Transfer-Encoding; bh=ImYOFm0MAebhNTUFGXynzS2XV7CBueaLVN4xxynXbUk=; b=R7HkKYeS9GgIvFG7OfpA/YG1M4b1v4BXglmHNYxQCQ//jKrssS93c58qk/K6hJzV/iaY oA/NFaKN7J9Dpw1T4BaKfFLaSFq/zSuypPYWKslr2yJ8vxNq51waHA7G9aDAn/8/qLzt/ PAffJo6jQ+AaQqfzf3gXt5kaCelxO8s4bvmEn2W+aNGZtcDZdzQ8LYHv5XVPsfBKPgqk+ 8wO7QAIVEyXSQGXGR8o9hcMdhWp5u4y03gpon0OV0gtP1oB5Lm9l6mlcfcTvn9U35adlW WaCIOET5F9oTXrV8An13J0q5QK2PAhYPfm9rOfKsxpXrUf2zKi3zHbZ1SfVKi0zsmcQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=VbTK68bA; arc=none smtp.remote-ip=95.215.58.113 Received: from mta1.migadu.com (out-113.mta1.migadu.com [95.215.58.113]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 67ADD606A329 for ; Wed, 4 Nov 2026 01:32:20 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 67ADD606A329 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=VbTK68bA X-Envelope-To: netdev@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=5LFImwIEYpEcOncv7J6XZb3AJW0OuTI7OHxkKVrqaDI=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1793755939; v=1; x=1794360739; b=VbTK68bA4KdqM/Jksd9s8OaycW5DtBsby1SFHwE/jmfZxw9/zBYXT3fIZif/Ocp86wqCrCsQ o4RGViSN6gxyzv/aGencVsPEYy3CSvloSPjBI0PnKszuL47cmyrCXkg95/vdsrN9jkJVkaXA9Lr RJAIFBrdkB7lEwML7TBJ4AqI= X-Envelope-To: netdev@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id c146b8be300003a3; Wed, 04 Nov 2026 01:32:19 +0000 X-Mizu-Trace-ID: c146b8be300003a3 X-Migadu-Flow: FLOW_OUT Message-ID: <4d3b8639-a313-444b-831a-f1f069882b86@linux.dev> Date: Wed, 4 Nov 2026 09:32:12 +0800 X-Mailing-List: netdev@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH bpf v2 03/15] bpf, sockmap: Don't let an SK_PASS verdict cover the next message To: Alexei Starovoitov , netdev-bot+sashiko@kernel.org Cc: bpf@vger.kernel.org, netdev@vger.kernel.org, daniel@iogearbox.net, andrii@kernel.org, eddyz87@gmail.com, memxor@gmail.com, john.fastabend@gmail.com, jakub@cloudflare.com, davem@davemloft.net, edumazet@kernel.org, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, kuniyu@google.com, willemb@google.com, matttbe@kernel.org, mptcp@lists.linux.dev, mason@kernel.org, josef@toxicpanda.com References: <20261102072112.4160195-4-alexei.starovoitov@gmail.com> <179374187706.488855.8366350890804573396@kernel.org> From: Jiayuan Chen In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 11/4/26 8:28 AM, Alexei Starovoitov wrote: > On Tue, Nov 03, 2026 at 01:37 PM netdev-bot+sashiko@kernel.org wrote: >>> + if (!psock->apply_bytes) >>> + psock->eval = __SK_NONE; >> When psock->apply_bytes is not 0, eval stays __SK_PASS during the push. >> The budget is still debited only after tcp_bpf_push() returns. Can a >> second sender on the same socket still get past the prog here? > Yes, as today. It's already explained in the commit log. > >> But B's message is sized against the budget before A's in-flight bytes >> are removed from it. Would it be better to reserve the budget before the >> push? That means debiting tosend, and ending the verdict when the budget >> reaches 0, before calling tcp_bpf_push(), instead of subtracting after a >> failure. > No. That breaks the single sender. After -EAGAIN the verdict has to > cover the bytes that the push didn't send. A refund after the failed > push can land on B's verdict. > >> The shared-cork problem with two PASS senders already existed. The kfree() >> variant used to need a third sender to end a byte-limited verdict. The >> early reset makes it reachable with only two senders. > yeah. It's an old bug, not from this patch. > Two senders are enough today too. B's first message goes out with A's > verdict, and the code after the switch resets eval. The prog runs on B's > second message. SK_REDIRECT frees the cork that A still pushes. > The log of patch 13 says that a cork is not safe for two senders. > Jiayuan proposed to serialize the senders in the reply to that patch. I will pick up thoes pre-existing issues and organize others reported by sashiko. >> With the early reset, can sender A's bytes be charged against a verdict >> that another sender installed? > Not a bug. eval, apply_bytes and sk_redir belong to the socket, not to > a thread. B's verdict ends early and the prog runs again for the rest.