From ac7c66698a2c51e4c6a34b84621c79e7cb89e07d Mon Sep 17 00:00:00 2001 From: "ODonnell, Michael" Date: Wed, 11 Jan 2006 11:26:22 -0800 Subject: [PATCH] [PATCH] corruption during e100 MDI register access We have identified two related bugs in the e100 driver. Both bugs are related to manipulation of the MDI control register. The first problem is that the Ready bit is being ignored when writing to the Control register; we noticed this because the Linux bonding driver would occasionally come to the spurious conclusion that the link was down when querying Link State. It turned out that by failing to wait for a previous command to complete it was selecting what was essentially a random register in the MDI register set. When we added code that waits for the Ready bit (as shown in the patch file below) all such problems ceased. The second problem is that, although access to the MDI registers involves multiple steps which must not be intermixed, nothing was defending against two or more threads attempting simultaneous access. The most obvious situation where such interference could occur involves the watchdog versus ioctl paths, but there are probably others, so we recommend the locking shown in our patch file. Signed-off-by: Michael O'Donnell Cc: "David S. Miller" Cc: Jeff Garzik Cc: John Ronciak Cc: Ganesh Venkatesan Cc: Jesse Brandeburg Signed-off-by: Andrew Morton Signed-off-by: Jeff Garzik --- drivers/net/e100.c | 32 +++++++++++++++++++++++++++++--- 1 file changed, 29 insertions(+), 3 deletions(-) diff --git a/drivers/net/e100.c b/drivers/net/e100.c index 22cd04556707..23de22631c64 100644 --- a/drivers/net/e100.c +++ b/drivers/net/e100.c @@ -132,6 +132,10 @@ * TODO: * o several entry points race with dev->close * o check for tx-no-resources/stop Q races with tx clean/wake Q + * + * FIXES: + * 2005/12/02 - Michael O'Donnell + * - Stratus87247: protect MDI control register manipulations */ #include @@ -578,6 +582,7 @@ struct nic { u16 leds; u16 eeprom_wc; u16 eeprom[256]; + spinlock_t mdio_lock; }; static inline void e100_write_flush(struct nic *nic) @@ -876,15 +881,35 @@ static u16 mdio_ctrl(struct nic *nic, u32 addr, u32 dir, u32 reg, u16 data) { u32 data_out = 0; unsigned int i; + unsigned long flags; + + /* + * Stratus87247: we shouldn't be writing the MDI control + * register until the Ready bit shows True. Also, since + * manipulation of the MDI control registers is a multi-step + * procedure it should be done under lock. + */ + spin_lock_irqsave(&nic->mdio_lock, flags); + for (i = 100; i; --i) { + if (readl(&nic->csr->mdi_ctrl) & mdi_ready) + break; + udelay(20); + } + if (unlikely(!i)) { + printk("e100.mdio_ctrl(%s) won't go Ready\n", + nic->netdev->name ); + spin_unlock_irqrestore(&nic->mdio_lock, flags); + return 0; /* No way to indicate timeout error */ + } writel((reg << 16) | (addr << 21) | dir | data, &nic->csr->mdi_ctrl); - for(i = 0; i < 100; i++) { + for (i = 0; i < 100; i++) { udelay(20); - if((data_out = readl(&nic->csr->mdi_ctrl)) & mdi_ready) + if ((data_out = readl(&nic->csr->mdi_ctrl)) & mdi_ready) break; } - + spin_unlock_irqrestore(&nic->mdio_lock, flags); DPRINTK(HW, DEBUG, "%s:addr=%d, reg=%d, data_in=0x%04X, data_out=0x%04X\n", dir == mdi_read ? "READ" : "WRITE", addr, reg, data, data_out); @@ -2562,6 +2587,7 @@ static int __devinit e100_probe(struct pci_dev *pdev, /* locks must be initialized before calling hw_reset */ spin_lock_init(&nic->cb_lock); spin_lock_init(&nic->cmd_lock); + spin_lock_init(&nic->mdio_lock); /* Reset the device before pci_set_master() in case device is in some * funky state and has an interrupt pending - hint: we don't have the -- 2.20.1