From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qk1-f202.google.com (mail-qk1-f202.google.com [209.85.222.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 04B1547D937 for ; Tue, 19 May 2026 09:46:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.222.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779183985; cv=none; b=JrZ86S1NV4Y+87z7bXzat5e3flvwxUfk/MWGLnfLhWdU2C0XblVH9bKDeWjJoawm+6eYutKzgLQ+Gug+uY3jtkZQYgA8pf1iwhVEKR+xuTsyZpxcWYOHqQTP+RDaejiy6aUatH0ohGq5ZkM17h9e2x53gFUuu2KrWL2EJIUqWQE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779183985; c=relaxed/simple; bh=0rElNsNA/eb6XNzrEbgNcvVO7tiSM7tXaYa/QPkVlvk=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=N6TNCHA1WW+A8jwP9ApCSJVjOPpXPALLsUHU7na4M4rty+vVj3FZ97+nLMEob4SaQB/jxfcOW5ZW2baazPp7lpLs/yhD8Ni9aUZhprjS4OpAm4SzAdys4dHi9bqM6lgJwwrSL5qRzSQ14nN++Qb0awLEvBA49a5bfIvRXg/I/14= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--edumazet.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=bhgY3C06; arc=none smtp.client-ip=209.85.222.202 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--edumazet.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="bhgY3C06" Received: by mail-qk1-f202.google.com with SMTP id af79cd13be357-90d175ae52bso561534085a.0 for ; Tue, 19 May 2026 02:46:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1779183983; x=1779788783; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=zLjwFt87P26Pi9lC+LK+r7j2frt3V80s4pt3ySyUPd0=; b=bhgY3C06Sz5tEeHzYvG4ziXlKE5pOpAkkETfNLufDhaAU8f+nYDnWfFOQaiVA7c8Bm xsKZ1sUF1MaUR4seILA+yvlnH+UROF3rVE196d0I7cBT5fhsP8Nw3Vp6Vb/3OUQo5KYa 7WvkOW6P8d/syAm/nVaymBChyocfcb+tPfHispA2wKBAAQqB2vkaUBrMnF21Xhy/DUND zcz0mWJQaoD7uCDKhWSpvAI7rW3DKFO7EjlfSN9+Bwqbu7URihuPrnhLf/XIBnsdrRKk g+pN1EK/qHDHCK9FGiIOApHRXTU0iz+hqcPMVr6/sd/lZcJZoP4StDUqhh6zApr3GFrn Tvag== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1779183983; x=1779788783; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=zLjwFt87P26Pi9lC+LK+r7j2frt3V80s4pt3ySyUPd0=; b=pTJgfxN8tuS/Z13a3fZ1aypjA4Uz0YyN8WaMmWdAR6hUfZTmO+HaRdyRwN6B4U0pf0 4WRH+k7rn4YICNf7Jjd1GUR5CUi4/JhaO0B2Dx5vYDME8e4nc4WUWSNueCQmljJ4dXNT y28gFCYecy0nSrxkNEGNujWilskLcvn7jXS/eAb32kxV2Y/SfxnRffpnm/c3WpJJSQKb EfrE4ofgbpvBAR23BUWfUrdY5KFNLwDNy6tqVmods+IeHquptNn7bOpU687iTyvWvMwA IMgQU/hLW07rz/coLGt7gWtFAV9TgPeibBQjxz/Tih0LBwJ5r7RDTti/2F3mWBK1iIQA x4qA== X-Forwarded-Encrypted: i=1; AFNElJ8duTkQTog0Ndsunf8AnOhXfgc3Z+tIP9D03RZNW8fnIyQ8U9zQZrLrNvIK/OnOYB/QhnnZ28U=@vger.kernel.org X-Gm-Message-State: AOJu0Yy7YJ2dMllRk9mkoLvf/V9+bkEId/MCaT62j5qrKrk5EltwHYc6 VLQVQ8W9xCulz15EdjB0XA8/cz0ira6KdWZ9a/h6/ldAIZ6lJuD9fNJBybc46fKxyFOre62iFQN GV/uT7F0ibd2BpQ== X-Received: from qkah9.prod.google.com ([2002:a05:620a:21c9:b0:912:b6f:1e86]) (user=edumazet job=prod-delivery.src-stubby-dispatcher) by 2002:a05:620a:c47:b0:90f:e60e:d4a8 with SMTP id af79cd13be357-911cdc4382emr2609888985a.34.1779183982763; Tue, 19 May 2026 02:46:22 -0700 (PDT) Date: Tue, 19 May 2026 09:46:18 +0000 In-Reply-To: <20260519094618.2632073-1-edumazet@google.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260519094618.2632073-1-edumazet@google.com> X-Mailer: git-send-email 2.54.0.563.g4f69b47b94-goog Message-ID: <20260519094618.2632073-3-edumazet@google.com> Subject: [PATCH net-next 2/2] net/sched: sch_drr: make cl->quantum lockless From: Eric Dumazet To: "David S . Miller" , Jakub Kicinski , Paolo Abeni Cc: Simon Horman , Jamal Hadi Salim , Victor Nogueira , Jiri Pirko , netdev@vger.kernel.org, eric.dumazet@gmail.com, Eric Dumazet Content-Type: text/plain; charset="UTF-8" cl->quantum does not need to be protected by RTNL or qdisc spinlock. Signed-off-by: Eric Dumazet --- net/sched/sch_drr.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/net/sched/sch_drr.c b/net/sched/sch_drr.c index 7da8c7c8421b7f2477c7c07d3b5920b375ce029e..020657f959b575667f7a4b4d6aacd05c03c654a0 100644 --- a/net/sched/sch_drr.c +++ b/net/sched/sch_drr.c @@ -97,10 +97,8 @@ static int drr_change_class(struct Qdisc *sch, u32 classid, u32 parentid, } } - sch_tree_lock(sch); if (tb[TCA_DRR_QUANTUM]) - cl->quantum = quantum; - sch_tree_unlock(sch); + WRITE_ONCE(cl->quantum, quantum); return 0; } @@ -251,7 +249,7 @@ static int drr_dump_class(struct Qdisc *sch, unsigned long arg, nest = nla_nest_start_noflag(skb, TCA_OPTIONS); if (nest == NULL) goto nla_put_failure; - if (nla_put_u32(skb, TCA_DRR_QUANTUM, cl->quantum)) + if (nla_put_u32(skb, TCA_DRR_QUANTUM, READ_ONCE(cl->quantum))) goto nla_put_failure; return nla_nest_end(skb, nest); @@ -362,7 +360,7 @@ static int drr_enqueue(struct sk_buff *skb, struct Qdisc *sch, if (!cl_is_active(cl)) { list_add_tail(&cl->alist, &q->active); - WRITE_ONCE(cl->deficit, cl->quantum); + WRITE_ONCE(cl->deficit, READ_ONCE(cl->quantum)); } qstats_backlog_add(sch, len); @@ -403,7 +401,7 @@ static struct sk_buff *drr_dequeue(struct Qdisc *sch) return skb; } - WRITE_ONCE(cl->deficit, cl->deficit + cl->quantum); + WRITE_ONCE(cl->deficit, cl->deficit + READ_ONCE(cl->quantum)); list_move_tail(&cl->alist, &q->active); } out: -- 2.54.0.563.g4f69b47b94-goog