From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f173.google.com (mail-pg1-f173.google.com [209.85.215.173]) (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 87B731EBFFF; Mon, 21 Apr 2025 19:17:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.173 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745263030; cv=none; b=T9Pb/+bRaqbx38a0HgaQf46zvNzX3nI7nHm8Da42NWMyCa5qRadZ/s5v123Hg+kHcQ38znX5BrPeHG5++1esykT3bCaTicUF+YjyW/uuxRGrFuSHtoCGzJ/Cl9aPgEnoPumsLHPdOd5lH94IckB+LcqSnjFsB/7r/7OMEdh6wdQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745263030; c=relaxed/simple; bh=vNVjzy6SY6NB8V0+5kVwIcx0deQrkMhPB96hHSvdq/8=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version:Content-Type; b=J8/HPBBqk49Tw/H73tHIqDmfV7mWDFeAN4AxsuS7hWWZgsP5PvOV3u3tzD9C4fpMlTT74I4N0a6ipj11m70HM781PPQfl6A0g6SjEfFSDhezLe8AbdAJdWGO+effK9H27SmSa5y4MpcrxDCGHDPYXHnWE+FkKSHhHqHReMudPiU= 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=LyWDJ/AQ; arc=none smtp.client-ip=209.85.215.173 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="LyWDJ/AQ" Received: by mail-pg1-f173.google.com with SMTP id 41be03b00d2f7-aee773df955so4277903a12.1; Mon, 21 Apr 2025 12:17:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1745263028; x=1745867828; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=F874gon9E3P4hwlV/yFSCkcXv75v2itLgs6pZvbeUpA=; b=LyWDJ/AQA8bnh+J+IZwX/LunlaUpPywOP5VoyhYzmA2TL3mmxW6X0yydPPm3VMD0p5 eyVimzavEFXh6yFEkp+0oKCOONglIFhvFW+nDXV7oOLjS4rWhDp7cCtisVZbAOmIcNyM 0YqH1+GpnWOlLK+No2GDFoffAflijkMaBwn2GxkDmTk2q3Svog1/mWs8BqDfZ1wngDFB m449sHL4eQP+8su+zxJzDzer24afyIpZ/cWzsxAt3CnF1YrhHv9Wy6kWqhdNORfZCfDC yQDOesKXsSKoKbK2G3VPKuxREc819vKptHWmIC3k8C/I+eybQFfZEXBJv9JqEbq3cUIT 6GZA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1745263028; x=1745867828; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=F874gon9E3P4hwlV/yFSCkcXv75v2itLgs6pZvbeUpA=; b=V+bK7wyX83QgG3p6+Co/YZsOB0Ctnal0qu2F2Ci44wwF2EFkN3gUtktBZVrp5xWQoO 3BlQHdXV1TA6O90cdPaURZedZs1nXUIrzr1PNt7n2HTVZdxOVjfVKPygUD/eNZkFcxjS MWEHT2MiddNPL+jDscfVVWjPm1EQ+AP72EV+D6vdwLgfCUj18fgmkQRtFmoMuAXsXTZT BPNJTAot8yIJ3LSPVtRnLlq7mjfDu5D9ZscKs62uMydsfOO4mqSybQbE2RTxaXroGoCh uvqKCLWUG0A3nk0eim7jWmb3S6bCHfOsV3TkU7MYR/Ek8wJonsm7QVhYE+txNJTiYSoS SIDw== X-Forwarded-Encrypted: i=1; AJvYcCU46gXrkxnuRbwld3DmjRSezuWHNvYJs3efw3KhE/RFGdanpVukBRNTIOzpjwiGRlJKoQZwHK2BlFb86xc=@vger.kernel.org, AJvYcCUugO8bZp9rBd9QXhOe/zRCuOzLF7Qv2vkKwaofnCEKdfFZoP20O0qRmYer7DXozKjwzERKxFn1@vger.kernel.org X-Gm-Message-State: AOJu0Yy4SrwzWBtcQ7Vab2BGuCWfd815X8iQ1OP3UoVJFAHXuL/a8Wiz GF1+uH+9Zqy46kkNPKSUpPwh3djm2RzKP3auixsNZzfZcrBEWudz X-Gm-Gg: ASbGncsdkSYrhwyrydN5fhH+JihASDjisTMmypmhmXalLbQ1xZexfzaUmCgzbEDATks 3vZESCSwRBB91pfS4SJFBXfKdod8axEhMk9MKIBppJzuCKnDIxpwS2N8IEexiITzUlLWgQcjTlG L/AaVLjmZWgeSa2FhwxoPF/4n76cbWimC3i59fvk+w56RXzFbXvmBPmPb4GFiu6LwgZumglHQf7 y7HazKWCydP0EBU1iiuAUq8Oaz+HHD4wjkGu9GwhzIpQcpjITSvLZ1TF6VieZe6uVGTqJbiTzNj G0Xu3u1y4nU0xKy1xWTBZiJnTCz+BBjWb0gD7LKNAw== X-Google-Smtp-Source: AGHT+IH6t+tcpp4993pIVk43Qfm1vQX+JJNqthrLys0H4E9YIC8cmt+4g1IsPuNP9Vkk7i0VPJDevA== X-Received: by 2002:a17:90b:51c1:b0:2ff:71d2:ee8f with SMTP id 98e67ed59e1d1-3087c361083mr19056772a91.13.1745263027604; Mon, 21 Apr 2025 12:17:07 -0700 (PDT) Received: from mythos-cloud.. ([125.138.201.7]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3087df24097sm6968738a91.21.2025.04.21.12.17.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 21 Apr 2025 12:17:07 -0700 (PDT) From: Moon Yeounsu To: Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: Moon Yeounsu , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH net-next] net: dlink: add synchronization for stats update Date: Tue, 22 Apr 2025 04:16:44 +0900 Message-ID: <20250421191645.43526-2-yyyynoom@gmail.com> X-Mailer: git-send-email 2.49.0 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit There are two paths that call `get_stats()`: 1. From user space via the `ip` command 2. From interrupt context via `rio_interrupt()` Case 1 is synchronized by `rtnl_lock()`, so it is safe. However, the two cases above are not synchronized with each other. Therefore, `spin_lock` is needed to protect `get_stats()` as it can be preempted by an interrupt. In this context, `spin_lock_irq()` is required (using `spin_lock_bh()` may result in a deadlock). While `spin_lock` protects `get_stats()`, it does not protect updates to `dev->stats.tx_errors` and `dev->stats.collisions`, which may be concurrently modified by the interrupt handler and user space. By using temporary variables in `np->tx_errors` and `np->collisions`, we can safely update `dev->stats` without additional locking. Tested-on: D-Link DGE-550T Rev-A3 Signed-off-by: Moon Yeounsu --- Question: This might be a bit off-topic, but I don’t fully understand why a single global `rtnl_lock` is used for synchronization. While I may not be fully aware of the design rationale, it seems somewhat suboptimal. I believe it could be improved. --- drivers/net/ethernet/dlink/dl2k.c | 11 +++++++++-- drivers/net/ethernet/dlink/dl2k.h | 5 +++++ 2 files changed, 14 insertions(+), 2 deletions(-) diff --git a/drivers/net/ethernet/dlink/dl2k.c b/drivers/net/ethernet/dlink/dl2k.c index d0ea92607870..2d929a83e101 100644 --- a/drivers/net/ethernet/dlink/dl2k.c +++ b/drivers/net/ethernet/dlink/dl2k.c @@ -865,7 +865,7 @@ tx_error (struct net_device *dev, int tx_status) frame_id = (tx_status & 0xffff0000); printk (KERN_ERR "%s: Transmit error, TxStatus %4.4x, FrameId %d.\n", dev->name, tx_status, frame_id); - dev->stats.tx_errors++; + np->tx_errors++; /* Ttransmit Underrun */ if (tx_status & 0x10) { dev->stats.tx_fifo_errors++; @@ -904,7 +904,7 @@ tx_error (struct net_device *dev, int tx_status) } /* Maximum Collisions */ if (tx_status & 0x08) - dev->stats.collisions++; + np->collisions++; /* Restart the Tx */ dw32(MACCtrl, dr16(MACCtrl) | TxEnable); } @@ -1074,6 +1074,7 @@ get_stats (struct net_device *dev) #endif unsigned int stat_reg; + spin_lock_irq(&np->stats_lock); /* All statistics registers need to be acknowledged, else statistic overflow could cause problems */ @@ -1085,6 +1086,7 @@ get_stats (struct net_device *dev) dev->stats.multicast = dr32(McstFramesRcvdOk); dev->stats.collisions += dr32(SingleColFrames) + dr32(MultiColFrames); + dev->stats.collisions += np->collisions; /* detailed tx errors */ stat_reg = dr16(FramesAbortXSColls); @@ -1095,6 +1097,8 @@ get_stats (struct net_device *dev) dev->stats.tx_carrier_errors += stat_reg; dev->stats.tx_errors += stat_reg; + dev->stats.tx_errors += np->tx_errors; + /* Clear all other statistic register. */ dr32(McstOctetXmtOk); dr16(BcstFramesXmtdOk); @@ -1123,6 +1127,9 @@ get_stats (struct net_device *dev) dr16(TCPCheckSumErrors); dr16(UDPCheckSumErrors); dr16(IPCheckSumErrors); + + spin_unlock_irq(&np->stats_lock); + return &dev->stats; } diff --git a/drivers/net/ethernet/dlink/dl2k.h b/drivers/net/ethernet/dlink/dl2k.h index 195dc6cfd895..dc8755a69b73 100644 --- a/drivers/net/ethernet/dlink/dl2k.h +++ b/drivers/net/ethernet/dlink/dl2k.h @@ -372,6 +372,8 @@ struct netdev_private { struct pci_dev *pdev; void __iomem *ioaddr; void __iomem *eeprom_addr; + // To ensure synchronization when stats are updated. + spinlock_t stats_lock; spinlock_t tx_lock; spinlock_t rx_lock; unsigned int rx_buf_sz; /* Based on MTU+slack. */ @@ -401,6 +403,9 @@ struct netdev_private { u16 negotiate; /* Negotiated media */ int phy_addr; /* PHY addresses. */ u16 led_mode; /* LED mode read from EEPROM (IP1000A only) */ + + u64 collisions; + u64 tx_errors; }; /* The station address location in the EEPROM. */ -- 2.49.0