From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qt1-f198.google.com (mail-qt1-f198.google.com [209.85.160.198]) (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 E433B569F14 for ; Tue, 22 Sep 2026 16:35:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.160.198 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790094903; cv=none; b=oRaiZyhyt0oNYRQXVG4AuBsMWVjobn+Tj8ON4zUlolqkFfWdB6ZTNmQKyeE2cBHhX4gKOzKTjkal/b2UIz0cRNS21h4yq2r4K+6nY5yGS36iMSAdoPtXwE9JJWeAF3461JIQ5hJEX65O5ZEK59jlu/VRZKrj3fApTquO7RSP9cc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790094903; c=relaxed/simple; bh=BB6dwNTdtcHi9uunM0bqFt+8k9jA0Qk9qrS84HL6qKg=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=Oipnvd6t12vCOWdkCnGF1ENsk31/+jzlVvyxBvJVSOlNfKyLR9cstw5K3j1h2VPS58kZvnS5JvayFzEjNM6/pikrsfP8RZgkp3MCoXzVCaqOTEQ8ICK4dBiU21GpJ6YB3UcVYHMu+eY01B9LLYOvPLOCryJIu+jGagFw+1czj+U= 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=eJ76Waw9; arc=none smtp.client-ip=209.85.160.198 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="eJ76Waw9" Received: by mail-qt1-f198.google.com with SMTP id d75a77b69052e-530256c61b4so1480561cf.3 for ; Tue, 22 Sep 2026 09:35:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1790094901; x=1790699701; darn=vger.kernel.org; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:from:to:cc:subject:date:message-id:reply-to :content-type; bh=Ok4MWBbItiOTuHBrYY/Sl72bi3aafQGdcryORVOWZhc=; b=eJ76Waw9OyFi3Y3BVExBXk9RaJZREF5kLFNTBkGUZ/p7hHbSlCKGJHqgliLIYT8+Rc QKJh1Dv7Xi1hZnjey1Paw8GNKvxBe8WS8ntRLtWjG7w7vX3WmFrvfVC2VcCuApuMdXnG 84kfCZ8usgTASVlKnbztntrafltiSdlw0oqkhFn3BbbKfwEUJfVt7ZB0D/jCi4p5ccq+ iT1aOqUrujy8kW1+SOqw/pDjDn/Irxqlt47vgpOlsu0yhD9+gv0Tf/NgStXNwFKUSJxC IVJEMz0Bi/b/0KInTFMapZWQDurCzw8EES2KTUygcU/KncmMbnz4+lFKtWYsFUwV+4dF 5sLA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1790094901; x=1790699701; h=content-type: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:content-type; bh=Ok4MWBbItiOTuHBrYY/Sl72bi3aafQGdcryORVOWZhc=; b=pi2Wv9TXHvA9DUsf6PVeofNf/2QSgZSDWmW20rPNXtHIzckUhX65yxzudof+9HKyI/ mtvAd36JDvJYL58GTal6M4YVKDYLcpo+r7iNWDH2ih8DNhCHE2d7QpVumHbHzXRa4Fr8 hDpQwsK81n4GpH9tbMIaj+0Wzu9KsBPEKnKLBZ2oh/i5/6zfCRIdZjIaMljFF95XKvk/ zA+fQQG6F1COOCZm+O6SMTCquQKKZ1u8osqsHdDf2nwjD50zOy3QAXDXfm1utLBWK9NA SADfD3NZ10DUyq9O76ucpp0MsU5xUdKy8+J5IX/+qzznC6tL9aPjGOouDxixhSWMm838 lXBA== X-Forwarded-Encrypted: i=1; AKwUvBw1JcJDNvG7P1sWA7ApRqPMUV+G62RvB4FaRLI94HXoC9Tu8oyxSiuRjAMM/SNiF8x2jLr0Gk8=@vger.kernel.org X-Gm-Message-State: AFuF++ly3fj5aVlHeD1ltjfk/oqOKiXRUC8Zsqzgr1x4t+a0A2ZYGwDe 7txbzrXQwx9km7igKpx+8aK6fX0z/4+38EAdRP9p9zC8VE8mFDuhUerXVz4cSEnTGXL3mswGA3W GwFAH7uxv53tp9A== X-Received: from qtbay29.prod.google.com ([2002:a05:622a:229d:b0:532:ad07:89a6]) (user=edumazet job=prod-delivery.src-stubby-dispatcher) by 2002:a05:622a:580e:b0:530:b2e4:d598 with SMTP id d75a77b69052e-532ead55dcemr1649031cf.51.1790094900435; Tue, 22 Sep 2026 09:35:00 -0700 (PDT) Date: Tue, 22 Sep 2026 16:34:55 +0000 In-Reply-To: <20260922163458.3900996-1-edumazet@google.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260922163458.3900996-1-edumazet@google.com> X-Mailer: git-send-email 2.55.0.1082.g2b9226bbc0-goog Message-ID: <20260922163458.3900996-2-edumazet@google.com> Subject: [PATCH v2 net-next 1/4] net: synchronize proc_do_rss_key() with netdev_rss_key_fill() From: Eric Dumazet To: "David S . Miller" , Jakub Kicinski , Paolo Abeni Cc: Willem de Bruijn , Simon Horman , netdev@vger.kernel.org, eric.dumazet@gmail.com, Eric Dumazet Content-Type: text/plain; charset="UTF-8" proc_do_rss_key() reads netdev_rss_key[] without synchronization, so a concurrent reader of /proc/sys/net/core/netdev_rss_key can observe a partially populated key while netdev_rss_key_fill() is initializing it. Publish a boolean flag after an smp_wmb() once netdev_rss_key_fill() has populated netdev_rss_key[], and pair it with an smp_rmb() in proc_do_rss_key(), printing zero bytes until the flag is set. Fixes: 960fb622f851 ("net: provide a per host RSS key generic infrastructure") Signed-off-by: Eric Dumazet --- net/core/dev.h | 1 + net/core/sysctl_net_core.c | 7 ++++++- net/ethtool/ioctl.c | 7 +++++++ 3 files changed, 14 insertions(+), 1 deletion(-) diff --git a/net/core/dev.h b/net/core/dev.h index b757faead4d1a3e445e54d2f468c38c9e09b6762..0127b4d03e5251e0ad695aa649d0c52c2248bc8c 100644 --- a/net/core/dev.h +++ b/net/core/dev.h @@ -95,6 +95,7 @@ extern int netdev_unregister_timeout_secs; extern int weight_p; extern int dev_weight_rx_bias; extern int dev_weight_tx_bias; +extern bool netdev_rss_key_initialized; extern struct rw_semaphore dev_addr_sem; diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c index 23310581f494553e3ad8c4e010c7799e04f976c0..473c162736d6928d13d22e9902262a43705196d9 100644 --- a/net/core/sysctl_net_core.c +++ b/net/core/sysctl_net_core.c @@ -337,10 +337,15 @@ static int proc_do_rss_key(const struct ctl_table *table, int write, { char buf[NETDEV_RSS_KEY_LEN * 3]; struct ctl_table fake_table; + bool initialized; char *pos = buf; + initialized = READ_ONCE(netdev_rss_key_initialized); + /* Pair with smp_wmb() in netdev_rss_key_fill(). */ + smp_rmb(); + for (int i = 0; i < NETDEV_RSS_KEY_LEN; i++) { - pos = hex_byte_pack(pos, netdev_rss_key[i]); + pos = hex_byte_pack(pos, initialized ? netdev_rss_key[i] : 0); *pos++ = ':'; } *(--pos) = 0; diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c index 4b0bc503f9307880e436d5ee30f75476264a0c6b..b2820f02ca2790a8a3c13395e20040ee6976006f 100644 --- a/net/ethtool/ioctl.c +++ b/net/ethtool/ioctl.c @@ -34,6 +34,7 @@ #include #include +#include "../core/dev.h" #include "common.h" /* State held across locks and calls for commands which have devlink fallback */ @@ -1302,11 +1303,17 @@ static int ethtool_copy_validate_indir(u32 *indir, void __user *useraddr, } u8 netdev_rss_key[NETDEV_RSS_KEY_LEN] __read_mostly; +bool netdev_rss_key_initialized __read_mostly; void netdev_rss_key_fill(void *buffer, size_t len) { BUG_ON(len > sizeof(netdev_rss_key)); net_get_random_once(netdev_rss_key, sizeof(netdev_rss_key)); + if (unlikely(!READ_ONCE(netdev_rss_key_initialized))) { + /* Pair with smp_rmb() in proc_do_rss_key(). */ + smp_wmb(); + WRITE_ONCE(netdev_rss_key_initialized, true); + } memcpy(buffer, netdev_rss_key, len); } EXPORT_SYMBOL(netdev_rss_key_fill); -- 2.55.0.1082.g2b9226bbc0-goog