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[13.212.242.176]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3a0812a1eb2sm1105330a91.4.2026.09.23.01.41.02 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Wed, 23 Sep 2026 01:41:04 -0700 (PDT) From: Ginger Li To: netdev@vger.kernel.org Cc: andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, linux-kernel@vger.kernel.org Subject: [PATCH net] net: dm9000: Fix a recursive lockup in the TX timeout path Date: Wed, 23 Sep 2026 16:40:55 +0800 Message-ID: <20260923084055.65091-1-ginger.jzllee@gmail.com> X-Mailer: git-send-email 2.46.0 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit dm9000_timeout() takes db->lock with interrupts disabled and then calls dm9000_init_dm9000(), which expects the caller to hold that lock and accesses the chip registers directly. For DM9000B devices dm9000_init_dm9000() also calls dm9000_phy_write(), and that function takes db->lock again, so the TX timeout path deadlocks on the same CPU. dm9000_phy_write() already skips db->addr_lock when db->in_timeout is set, because in that case the caller holds db->lock and sleeping is not allowed either. Skip db->lock as well then, so that the nested call from dm9000_init_dm9000() works as intended. Fixes: 6741f40 ("DM9000B: driver initialization upgrade") Signed-off-by: Ginger Li --- drivers/net/ethernet/davicom/dm9000.c | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-) diff --git a/drivers/net/ethernet/davicom/dm9000.c b/drivers/net/ethernet/davicom/dm9000.c --- a/drivers/net/ethernet/davicom/dm9000.c +++ b/drivers/net/ethernet/davicom/dm9000.c @@ -325,10 +325,10 @@ dm9000_phy_write(struct net_device *dev, unsigned long reg_save; dm9000_dbg(db, 5, "phy_write[%02x] = %04x\n", reg, value); - if (!db->in_timeout) + if (!db->in_timeout) { mutex_lock(&db->addr_lock); - - spin_lock_irqsave(&db->lock, flags); + spin_lock_irqsave(&db->lock, flags); + } /* Save previous register address */ reg_save = readb(db->io_addr); @@ -344,11 +344,14 @@ dm9000_phy_write(struct net_device *dev, iow(db, DM9000_EPCR, EPCR_EPOS | EPCR_ERPRW); writeb(reg_save, db->io_addr); - spin_unlock_irqrestore(&db->lock, flags); + if (!db->in_timeout) + spin_unlock_irqrestore(&db->lock, flags); dm9000_msleep(db, 1); /* Wait write complete */ - spin_lock_irqsave(&db->lock, flags); + if (!db->in_timeout) + spin_lock_irqsave(&db->lock, flags); + reg_save = readb(db->io_addr); iow(db, DM9000_EPCR, 0x0); /* Clear phyxcer write command */ @@ -356,9 +359,10 @@ dm9000_phy_write(struct net_device *dev, /* restore the previous address */ writeb(reg_save, db->io_addr); - spin_unlock_irqrestore(&db->lock, flags); - if (!db->in_timeout) + if (!db->in_timeout) { + spin_unlock_irqrestore(&db->lock, flags); mutex_unlock(&db->addr_lock); + } } /* dm9000_set_io -- 2.43.0