From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f173.google.com (mail-pf1-f173.google.com [209.85.210.173]) (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 D00AE3EB0E8 for ; Tue, 4 Aug 2026 17:14:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.173 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785863708; cv=none; b=nqsAjnDihKZ4K1Y7dLe0/5L0900eBjh1h6FSYe/a1fbpXML2fj0h+nZJZ/U5/HhVGRd+/cWZY5aH9tX5JyVN2prjUtzyog/kE6rOSLfg4d/a6Z/jDFEPfi7infQ5OjUgCb7eFq/XsP5pXGU6qE43Wd0r6T+AGP9ltkkuSgjKJqs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785863708; c=relaxed/simple; bh=CDg7R4z19rm3HhNKcpDry/8FXJmNNTW/k1bNkbouDnA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=op6VhvRS/Z5gskLW48jb14vZHuHEKSg8JchyDqfefc7RSQ4RMFvpfGJq9tG3zpWANe1E1fyLoildZPtr5heY1BMemKU3tM2gHRvKYqQoaV8cr3wKHlt8SSQx2ay4h/cYF321orp0qwRAJeR1+DVaY93Q3jyO21nU1dBgugp8gm4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=Tmc0909F; arc=none smtp.client-ip=209.85.210.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Tmc0909F" Received: by mail-pf1-f173.google.com with SMTP id d2e1a72fcca58-84847482584so163525b3a.0 for ; Tue, 04 Aug 2026 10:14:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1785863693; x=1786468493; darn=vger.kernel.org; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:from:to:cc:subject :date:message-id:reply-to:content-type; bh=+FyhIVgwr2eNJZrKd4apq3PGwedIYUrqhXnEIT+9gD0=; b=Tmc0909Fbx4wvfuc8YQaau8WA430Z0l5R23o64tJN0MXXVaNqEr/lEgTnvwwM0p/YN 5PhTICdctolgRCT+oid4JmxUEtJiS1c5Zu+m7haLWGeXWc/ryZXOzDkfj2vfcG1tDUtI 1tSB0Sx+hLPHTC63EkJ/O6/DdN+aRno8s2kSCfzPWrlgmX1Ozpk7tW4sH2CX6huUhwn3 P8X01kMYx06vJzxJt0qEvvd8n817HdLOgQXbYdCIYaOmH/k7uzEMbYeIcU2mdbFL3uUX Zzftbi0Q8Ak4mw/G4IiaT1hXx4BhFEJ8Wy3tAKkIt6Zs3fK+YhzQc4YYdQ79QjuS7Jc3 awyg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1785863693; x=1786468493; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=+FyhIVgwr2eNJZrKd4apq3PGwedIYUrqhXnEIT+9gD0=; b=Hh4gUZavpWHdEFcNiy2okJXWdfS7sHPd+M7aBmtqjZV8nwXnAWA1QO4J5XfuOtDlNy dn9DGgmbY7kUxnrlYs9TA6JxcisYAA3PI00QlZEU5kftkWBpyhTc4gi6qaS6ndUqaeNB 5iH6dd9PPTWtUDicCwVJvv5rmQDJEt3x6E0Yk51DxdeMlb52XZvufdpFKOzSk5CeMF6P dzC3XIfKCjFTOL1iCmR974SLvFL7rQl22zD4UC+34NGVBPUxciGt+TIq8E1tPnhajFWI KoLtR9zC1DEMPHHlzfxl+ryiow3Oc3r1zkL4BTt1h67Z5AA2ZmB2BmP4bwfTi8FspaAS iGmQ== X-Forwarded-Encrypted: i=1; AHgh+RoUHp0P79Zy9jW05g7MNAFc48Unu857cWDm/rfgnDdk3OKJq8/6KJwH8NwN7NOTUML27IRxueYLfIrqGI0=@vger.kernel.org X-Gm-Message-State: AOJu0YzvQDhMBOjV6RY+bhMocRpUmhRVJrM/kwzv2WgLIENfKJt6enc1 h1pd0NZ8cF7MJnyQQ0hqE81MiyGaAAwLNZ1EKt0ZWHv5p+EvNQjLaYp1 X-Gm-Gg: AR+sD13hsFUg9ymKqTwOXj4HCdIJsGq3KkA8h510DD9vnWB0GEkxt/IhXBqtHTPpwIg gNbGf4gh8NagkBwFQDFAhNGDtWs7/mfBMhsD5FGx+r87n+umEnEpW1MblTERDVuRiLGvgIJWmoC 0xB/Y8maP5yPhZLJ1HcBwYRT89/0Lvs7G3E9+PrAwhv7x719mlP9lk1tZapXAXD0akL+kesIkoe j0R6dQEAtP67Hjb5Qzjmb9nzY6R2c5XtgN31sG0x8MrkJK2XrsU+4xxGSeaAxbIiFSIa4sNxfLH wZ6rC72t9RdqV9xaLUFie1RQkLCmEyIDhsbPSLDUTEK0QowCQm1JdDkNyd7S0MnOtXtVXCyCeWt eG/r7SwvZADX6hJx1XguCkWNf0y+NSDNK24I3AfDFiMJ9DzbvJhRwPPWIgxPliGzoH+L4KYcbCo f3J6q+OaIibUC1WZyTFuPIXxaC4jbwyWXcsXo15QAN91hYVX1FcUOl88b1KBHpiVxpMOEZwfBLl fmdXX3wRQ== X-Received: by 2002:a05:6a00:12c9:b0:848:50ef:4157 with SMTP id d2e1a72fcca58-84f1cb966c9mr4481009b3a.27.1785863692576; Tue, 04 Aug 2026 10:14:52 -0700 (PDT) Received: from devvm29614.prn0.facebook.com ([2a03:2880:ff:4a::]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-cbe707c9970sm77984a12.6.2026.08.04.10.14.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 04 Aug 2026 10:14:51 -0700 (PDT) Date: Tue, 4 Aug 2026 10:14:49 -0700 From: Bobby Eshleman To: Tariq Toukan Cc: Saeed Mahameed , Mark Bloch , Leon Romanovsky , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Dragos Tatulea , Mina Almasry , netdev@vger.kernel.org, linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org, Bobby Eshleman Subject: Re: [PATCH net v3] net/mlx5e: fix BQL reset on SQ re-activation Message-ID: References: <20260803-mlx5-bql-v3-1-a30d4c66fe1d@meta.com> <6ac643bf-c6f4-4ff2-ba57-964a645d9323@nvidia.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6ac643bf-c6f4-4ff2-ba57-964a645d9323@nvidia.com> On Tue, Aug 04, 2026 at 11:23:53AM +0300, Tariq Toukan wrote: > > > On 04/08/2026 2:47, Bobby Eshleman wrote: > > From: Bobby Eshleman > > > > mlx5e_queue_start() deactivates and re-activates all channels but closes > > only the queue being restarted. mlx5e_activate_txqsq() then > > unconditionally calls netdev_tx_reset_queue(), zeroing the BQL counters > > of channels that kept their in-flight TX WQEs. The next completion then > > over-charges and trips the BUG_ON() in dql_completed(): > > > > kernel BUG at lib/dynamic_queue_limits.c:99! > > RIP: 0010:dql_completed+0x23d/0x280 > > Call Trace: > > > > mlx5e_poll_tx_cq+0x668/0xa60 > > mlx5e_napi_poll+0x5b/0x7b0 > > net_rx_action+0x15a/0x580 > > > > Reset BQL only when the SQ has no bytes in flight (sq->cc == sq->pc). > > > > In the case that reset is skipped, the outstanding WQEs will eventually > > complete and rebalance the dql. The dql->limit is carried across the > > reset. > > > > Fixes: b2588ea40ec9 ("net/mlx5e: Implement queue mgmt ops and single channel swap") > > Signed-off-by: Bobby Eshleman > > Reviewed-by: Tariq Toukan > > Thanks. Thanks Tariq, and my apologies for forgetting to carry the R-b forward. > > > --- > > Changes in v3: > > - Sample sq->cc/sq->pc before setting MLX5E_SQ_STATE_ENABLED, so a > > concurrent mlx5e_poll_tx_cq() cannot un-charge BQL between the check > > and netdev_tx_reset_queue() (Sashiko: > > https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20260729-mlx5-bql-v2-1-cdf285e586df@meta.com) > > - Link to v2: https://lore.kernel.org/r/20260729-mlx5-bql-v2-1-cdf285e586df@meta.com > > > > Changes in v2: > > - remove misleading comment (Tariq) > > - Link to v1: https://lore.kernel.org/r/20260728-mlx5-bql-v1-1-99a0ab77ede7@meta.com > > --- > > drivers/net/ethernet/mellanox/mlx5/core/en_main.c | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c > > index 7d47a1da8b6b..f0407a850ea8 100644 > > --- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c > > +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c > > @@ -1939,8 +1939,10 @@ int mlx5e_open_txqsq(struct mlx5e_channel *c, u32 tisn, int txq_ix, > > void mlx5e_activate_txqsq(struct mlx5e_txqsq *sq) > > { > > sq->txq = netdev_get_tx_queue(sq->netdev, sq->txq_ix); > > + /* Reset BQL only when the SQ has no bytes in flight. */ > > + if (sq->cc == sq->pc) > > + netdev_tx_reset_queue(sq->txq); > > set_bit(MLX5E_SQ_STATE_ENABLED, &sq->state); > > - netdev_tx_reset_queue(sq->txq); > > netif_tx_start_queue(sq->txq); > > netif_queue_set_napi(sq->netdev, sq->txq_ix, NETDEV_QUEUE_TYPE_TX, sq->cq.napi); > > } > > > > --- > > base-commit: d1000fd7995e51deec872d154e0a40d82f7a539f > > change-id: 20260728-mlx5-bql-84e02a5a46c8 > > > > Best regards, >