diff mbox series

[02/19] usbnet: smsc95xx: Stop propagation of in_pm

Message ID 20190103011040.25974-3-marex@denx.de
State Changes Requested
Delegated to: David Miller
Headers show
Series [01/19] usbnet: smsc95xx: Fix memory leak in smsc95xx_bind | expand

Commit Message

Marek Vasut Jan. 3, 2019, 1:10 a.m. UTC 
The information whether the SMSC95xx is in_pm or not can be derived from
the usbdev->suspend_count. First thing called in smsc95xx_suspend() is
usbnet_suspend(), which increments the usbdev->suspend_count and since
then the driver only calls _nopm() functions and functions with in_pm
set to 1. The smsc95xx_resume() does the inverse, it calls functions
with _nopm() suffix and with in_pm set to 1 until usbnet_resume(), which
sets the usbdev->suspend_count to 0.

Thus, this patch replaces all the in_pm variables used throughout the
driver with simple call to smsc95xx_in_pm(), which checks whether the
usbdev->suspend_count is zero or not.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: David S. Miller <davem@davemloft.net>
Cc: Nisar Sayed <Nisar.Sayed@microchip.com>
Cc: Woojung Huh <Woojung.Huh@microchip.com>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: linux-usb@vger.kernel.org
To: netdev@vger.kernel.org
---
 drivers/net/usb/smsc95xx.c | 63 ++++++++++++++++++++------------------
 1 file changed, 33 insertions(+), 30 deletions(-)

Comments

Oliver Neukum Jan. 7, 2019, 11:02 a.m. UTC | #1 
On Do, 2019-01-03 at 02:10 +0100, Marek Vasut wrote:
> The information whether the SMSC95xx is in_pm or not can be derived from
> the usbdev->suspend_count. First thing called in smsc95xx_suspend() is
> usbnet_suspend(), which increments the usbdev->suspend_count and since
> then the driver only calls _nopm() functions and functions with in_pm
> set to 1. The smsc95xx_resume() does the inverse, it calls functions
> with _nopm() suffix and with in_pm set to 1 until usbnet_resume(), which
> sets the usbdev->suspend_count to 0.

Hi,

unfortunately I am forced to disagree in the strongest terms.

The logic behind this patch is wrong. The "in_pm" parameter
exists because some function need to be called in the code paths
needed to implement power management. Under those circumstances
they must not take a pm reference to keep the device awake, lest
the driver deadlock.
(For example __smsc95xx_read_reg)

However from other code paths precisely that reference must be taken
in order to make sure that the driver do not try to communicate with
a suspended device.
If you check the suspend counter, you will omit the necessary getting
of a reference precisely when it is needed. The driver will never
dedalock, but you will cause numerous races.

I must suggest to simply drop this part and redo the series.

	Regards
		Oliver
Marek Vasut Jan. 7, 2019, 11:50 a.m. UTC | #2 
On 1/7/19 12:02 PM, Oliver Neukum wrote:
> On Do, 2019-01-03 at 02:10 +0100, Marek Vasut wrote:
>> The information whether the SMSC95xx is in_pm or not can be derived from
>> the usbdev->suspend_count. First thing called in smsc95xx_suspend() is
>> usbnet_suspend(), which increments the usbdev->suspend_count and since
>> then the driver only calls _nopm() functions and functions with in_pm
>> set to 1. The smsc95xx_resume() does the inverse, it calls functions
>> with _nopm() suffix and with in_pm set to 1 until usbnet_resume(), which
>> sets the usbdev->suspend_count to 0.
> 
> Hi,

Hello Oliver,

> unfortunately I am forced to disagree in the strongest terms.
> 
> The logic behind this patch is wrong. The "in_pm" parameter
> exists because some function need to be called in the code paths
> needed to implement power management. Under those circumstances
> they must not take a pm reference to keep the device awake, lest
> the driver deadlock.
> (For example __smsc95xx_read_reg)
> 
> However from other code paths precisely that reference must be taken
> in order to make sure that the driver do not try to communicate with
> a suspended device.
> If you check the suspend counter, you will omit the necessary getting
> of a reference precisely when it is needed. The driver will never
> dedalock, but you will cause numerous races.
> 
> I must suggest to simply drop this part and redo the series.

OK, let's drop the whole series.
diff mbox series

Patch

diff --git a/drivers/net/usb/smsc95xx.c b/drivers/net/usb/smsc95xx.c
index 772429c17ae1..c74183b51d5b 100644
--- a/drivers/net/usb/smsc95xx.c
+++ b/drivers/net/usb/smsc95xx.c
@@ -82,8 +82,13 @@  static bool turbo_mode = true;
 module_param(turbo_mode, bool, 0644);
 MODULE_PARM_DESC(turbo_mode, "Enable multiple frames per Rx transaction");
 
+static int smsc95xx_in_pm(struct usbnet *dev)
+{
+	return dev->suspend_count != 0;
+}
+
 static int __must_check __smsc95xx_read_reg(struct usbnet *dev, u32 index,
-					    u32 *data, int in_pm)
+					    u32 *data)
 {
 	u32 buf;
 	int ret;
@@ -91,7 +96,7 @@  static int __must_check __smsc95xx_read_reg(struct usbnet *dev, u32 index,
 
 	BUG_ON(!dev);
 
-	if (!in_pm)
+	if (!smsc95xx_in_pm(dev))
 		fn = usbnet_read_cmd;
 	else
 		fn = usbnet_read_cmd_nopm;
@@ -112,7 +117,7 @@  static int __must_check __smsc95xx_read_reg(struct usbnet *dev, u32 index,
 }
 
 static int __must_check __smsc95xx_write_reg(struct usbnet *dev, u32 index,
-					     u32 data, int in_pm)
+					     u32 data)
 {
 	u32 buf;
 	int ret;
@@ -120,7 +125,7 @@  static int __must_check __smsc95xx_write_reg(struct usbnet *dev, u32 index,
 
 	BUG_ON(!dev);
 
-	if (!in_pm)
+	if (!smsc95xx_in_pm(dev))
 		fn = usbnet_write_cmd;
 	else
 		fn = usbnet_write_cmd_nopm;
@@ -141,38 +146,37 @@  static int __must_check __smsc95xx_write_reg(struct usbnet *dev, u32 index,
 static int __must_check smsc95xx_read_reg_nopm(struct usbnet *dev, u32 index,
 					       u32 *data)
 {
-	return __smsc95xx_read_reg(dev, index, data, 1);
+	return __smsc95xx_read_reg(dev, index, data);
 }
 
 static int __must_check smsc95xx_write_reg_nopm(struct usbnet *dev, u32 index,
 						u32 data)
 {
-	return __smsc95xx_write_reg(dev, index, data, 1);
+	return __smsc95xx_write_reg(dev, index, data);
 }
 
 static int __must_check smsc95xx_read_reg(struct usbnet *dev, u32 index,
 					  u32 *data)
 {
-	return __smsc95xx_read_reg(dev, index, data, 0);
+	return __smsc95xx_read_reg(dev, index, data);
 }
 
 static int __must_check smsc95xx_write_reg(struct usbnet *dev, u32 index,
 					   u32 data)
 {
-	return __smsc95xx_write_reg(dev, index, data, 0);
+	return __smsc95xx_write_reg(dev, index, data);
 }
 
 /* Loop until the read is completed with timeout
  * called with phy_mutex held */
-static int __must_check __smsc95xx_phy_wait_not_busy(struct usbnet *dev,
-						     int in_pm)
+static int __must_check __smsc95xx_phy_wait_not_busy(struct usbnet *dev)
 {
 	unsigned long start_time = jiffies;
 	u32 val;
 	int ret;
 
 	do {
-		ret = __smsc95xx_read_reg(dev, MII_ADDR, &val, in_pm);
+		ret = __smsc95xx_read_reg(dev, MII_ADDR, &val);
 		if (ret < 0) {
 			netdev_warn(dev->net, "Error reading MII_ACCESS\n");
 			return ret;
@@ -185,8 +189,7 @@  static int __must_check __smsc95xx_phy_wait_not_busy(struct usbnet *dev,
 	return -EIO;
 }
 
-static int __smsc95xx_mdio_read(struct net_device *netdev, int phy_id, int idx,
-				int in_pm)
+static int __smsc95xx_mdio_read(struct net_device *netdev, int phy_id, int idx)
 {
 	struct usbnet *dev = netdev_priv(netdev);
 	u32 val, addr;
@@ -195,7 +198,7 @@  static int __smsc95xx_mdio_read(struct net_device *netdev, int phy_id, int idx,
 	mutex_lock(&dev->phy_mutex);
 
 	/* confirm MII not busy */
-	ret = __smsc95xx_phy_wait_not_busy(dev, in_pm);
+	ret = __smsc95xx_phy_wait_not_busy(dev);
 	if (ret < 0) {
 		netdev_warn(dev->net, "MII is busy in smsc95xx_mdio_read\n");
 		goto done;
@@ -205,19 +208,19 @@  static int __smsc95xx_mdio_read(struct net_device *netdev, int phy_id, int idx,
 	phy_id &= dev->mii.phy_id_mask;
 	idx &= dev->mii.reg_num_mask;
 	addr = (phy_id << 11) | (idx << 6) | MII_READ_ | MII_BUSY_;
-	ret = __smsc95xx_write_reg(dev, MII_ADDR, addr, in_pm);
+	ret = __smsc95xx_write_reg(dev, MII_ADDR, addr);
 	if (ret < 0) {
 		netdev_warn(dev->net, "Error writing MII_ADDR\n");
 		goto done;
 	}
 
-	ret = __smsc95xx_phy_wait_not_busy(dev, in_pm);
+	ret = __smsc95xx_phy_wait_not_busy(dev);
 	if (ret < 0) {
 		netdev_warn(dev->net, "Timed out reading MII reg %02X\n", idx);
 		goto done;
 	}
 
-	ret = __smsc95xx_read_reg(dev, MII_DATA, &val, in_pm);
+	ret = __smsc95xx_read_reg(dev, MII_DATA, &val);
 	if (ret < 0) {
 		netdev_warn(dev->net, "Error reading MII_DATA\n");
 		goto done;
@@ -231,7 +234,7 @@  static int __smsc95xx_mdio_read(struct net_device *netdev, int phy_id, int idx,
 }
 
 static void __smsc95xx_mdio_write(struct net_device *netdev, int phy_id,
-				  int idx, int regval, int in_pm)
+				  int idx, int regval)
 {
 	struct usbnet *dev = netdev_priv(netdev);
 	u32 val, addr;
@@ -240,14 +243,14 @@  static void __smsc95xx_mdio_write(struct net_device *netdev, int phy_id,
 	mutex_lock(&dev->phy_mutex);
 
 	/* confirm MII not busy */
-	ret = __smsc95xx_phy_wait_not_busy(dev, in_pm);
+	ret = __smsc95xx_phy_wait_not_busy(dev);
 	if (ret < 0) {
 		netdev_warn(dev->net, "MII is busy in smsc95xx_mdio_write\n");
 		goto done;
 	}
 
 	val = regval;
-	ret = __smsc95xx_write_reg(dev, MII_DATA, val, in_pm);
+	ret = __smsc95xx_write_reg(dev, MII_DATA, val);
 	if (ret < 0) {
 		netdev_warn(dev->net, "Error writing MII_DATA\n");
 		goto done;
@@ -257,13 +260,13 @@  static void __smsc95xx_mdio_write(struct net_device *netdev, int phy_id,
 	phy_id &= dev->mii.phy_id_mask;
 	idx &= dev->mii.reg_num_mask;
 	addr = (phy_id << 11) | (idx << 6) | MII_WRITE_ | MII_BUSY_;
-	ret = __smsc95xx_write_reg(dev, MII_ADDR, addr, in_pm);
+	ret = __smsc95xx_write_reg(dev, MII_ADDR, addr);
 	if (ret < 0) {
 		netdev_warn(dev->net, "Error writing MII_ADDR\n");
 		goto done;
 	}
 
-	ret = __smsc95xx_phy_wait_not_busy(dev, in_pm);
+	ret = __smsc95xx_phy_wait_not_busy(dev);
 	if (ret < 0) {
 		netdev_warn(dev->net, "Timed out writing MII reg %02X\n", idx);
 		goto done;
@@ -276,24 +279,24 @@  static void __smsc95xx_mdio_write(struct net_device *netdev, int phy_id,
 static int smsc95xx_mdio_read_nopm(struct net_device *netdev, int phy_id,
 				   int idx)
 {
-	return __smsc95xx_mdio_read(netdev, phy_id, idx, 1);
+	return __smsc95xx_mdio_read(netdev, phy_id, idx);
 }
 
 static void smsc95xx_mdio_write_nopm(struct net_device *netdev, int phy_id,
 				     int idx, int regval)
 {
-	__smsc95xx_mdio_write(netdev, phy_id, idx, regval, 1);
+	__smsc95xx_mdio_write(netdev, phy_id, idx, regval);
 }
 
 static int smsc95xx_mdio_read(struct net_device *netdev, int phy_id, int idx)
 {
-	return __smsc95xx_mdio_read(netdev, phy_id, idx, 0);
+	return __smsc95xx_mdio_read(netdev, phy_id, idx);
 }
 
 static void smsc95xx_mdio_write(struct net_device *netdev, int phy_id, int idx,
 				int regval)
 {
-	__smsc95xx_mdio_write(netdev, phy_id, idx, regval, 0);
+	__smsc95xx_mdio_write(netdev, phy_id, idx, regval);
 }
 
 static int __must_check smsc95xx_wait_eeprom(struct usbnet *dev)
@@ -972,7 +975,7 @@  static int smsc95xx_start_tx_path(struct usbnet *dev)
 }
 
 /* Starts the Receive path */
-static int smsc95xx_start_rx_path(struct usbnet *dev, int in_pm)
+static int smsc95xx_start_rx_path(struct usbnet *dev)
 {
 	struct smsc95xx_priv *pdata = (struct smsc95xx_priv *)(dev->data[0]);
 	unsigned long flags;
@@ -981,7 +984,7 @@  static int smsc95xx_start_rx_path(struct usbnet *dev, int in_pm)
 	pdata->mac_cr |= MAC_CR_RXEN_;
 	spin_unlock_irqrestore(&pdata->mac_cr_lock, flags);
 
-	return __smsc95xx_write_reg(dev, MAC_CR, pdata->mac_cr, in_pm);
+	return __smsc95xx_write_reg(dev, MAC_CR, pdata->mac_cr);
 }
 
 static int smsc95xx_phy_initialize(struct usbnet *dev)
@@ -1233,7 +1236,7 @@  static int smsc95xx_reset(struct usbnet *dev)
 		return ret;
 	}
 
-	ret = smsc95xx_start_rx_path(dev, 0);
+	ret = smsc95xx_start_rx_path(dev);
 	if (ret < 0) {
 		netdev_warn(dev->net, "Failed to start RX path\n");
 		return ret;
@@ -1833,7 +1836,7 @@  static int smsc95xx_suspend(struct usb_interface *intf, pm_message_t message)
 		goto done;
 
 	/* enable receiver to enable frame reception */
-	smsc95xx_start_rx_path(dev, 1);
+	smsc95xx_start_rx_path(dev);
 
 	/* some wol options are enabled, so enter SUSPEND0 */
 	netdev_info(dev->net, "entering SUSPEND0 mode\n");