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([125.138.201.7]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-b15fa906da6sm3462952a12.62.2025.04.25.16.15.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 25 Apr 2025 16:15:24 -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 v2] net: dlink: add synchronization for stats update Date: Sat, 26 Apr 2025 08:13:52 +0900 Message-ID: <20250425231352.102535-2-yyyynoom@gmail.com> X-Mailer: git-send-email 2.49.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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). `dev->stats.tx_errors` and `dev->stats.collisions` may be concurrently modified by the interrupt handler and user space, so they are also protected by `spin_lock`. Tested-on: D-Link DGE-550T Rev-A3 Signed-off-by: Moon Yeounsu --- Changelog: v1: https://lore.kernel.org/netdev/20250421191645.43526-2-yyyynoom@gmail.co= m/ v2: - fix incorrect method of updating `dev->stats.tx_errors` and `dev->stats.collisions` --- drivers/net/ethernet/dlink/dl2k.c | 11 ++++++++++- drivers/net/ethernet/dlink/dl2k.h | 2 ++ 2 files changed, 12 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/dlink/dl2k.c b/drivers/net/ethernet/dlink= /dl2k.c index d88fbecdab4b..0a3ac9ba3729 100644 --- a/drivers/net/ethernet/dlink/dl2k.c +++ b/drivers/net/ethernet/dlink/dl2k.c @@ -865,7 +865,6 @@ tx_error (struct net_device *dev, int tx_status) frame_id =3D (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++; /* Ttransmit Underrun */ if (tx_status & 0x10) { dev->stats.tx_fifo_errors++; @@ -902,9 +901,15 @@ tx_error (struct net_device *dev, int tx_status) rio_set_led_mode(dev); /* Let TxStartThresh stay default value */ } + + spin_lock_irq(&np->stats_lock); /* Maximum Collisions */ if (tx_status & 0x08) dev->stats.collisions++; + + dev->stats.tx_errors++; + spin_unlock_irq(&np->stats_lock); + /* Restart the Tx */ dw32(MACCtrl, dr16(MACCtrl) | TxEnable); } @@ -1074,6 +1079,7 @@ get_stats (struct net_device *dev) #endif unsigned int stat_reg; =20 + spin_lock_irq(&np->stats_lock); /* All statistics registers need to be acknowledged, else statistic overflow could cause problems */ =20 @@ -1123,6 +1129,9 @@ get_stats (struct net_device *dev) dr16(TCPCheckSumErrors); dr16(UDPCheckSumErrors); dr16(IPCheckSumErrors); + + spin_unlock_irq(&np->stats_lock); + return &dev->stats; } =20 diff --git a/drivers/net/ethernet/dlink/dl2k.h b/drivers/net/ethernet/dlink= /dl2k.h index 195dc6cfd895..c24823e909ef 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. */ --=20 2.49.0