The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 7b960c967f2aa01ab8f45c5a0bd78e754cffdeee Mon Sep 17 00:00:00 2001 From: Lukas Wunner lukas@wunner.de Date: Fri, 1 Jul 2022 22:47:51 +0200 Subject: [PATCH] usbnet: smsc95xx: Fix deadlock on runtime resume
Commit 05b35e7eb9a1 ("smsc95xx: add phylib support") amended smsc95xx_resume() to call phy_init_hw(). That function waits for the device to runtime resume even though it is placed in the runtime resume path, causing a deadlock.
The problem is that phy_init_hw() calls down to smsc95xx_mdiobus_read(), which never uses the _nopm variant of usbnet_read_cmd().
Commit b4df480f68ae ("usbnet: smsc95xx: add reset_resume function with reset operation") causes a similar deadlock on resume if the device was already runtime suspended when entering system sleep:
That's because the commit introduced smsc95xx_reset_resume(), which calls down to smsc95xx_reset(), which neglects to use _nopm accessors.
Fix by auto-detecting whether a device access is performed by the suspend/resume task_struct and use the _nopm variant if so. This works because the PM core guarantees that suspend/resume callbacks are run in task context.
Stacktrace for posterity:
INFO: task kworker/2:1:49 blocked for more than 122 seconds. Workqueue: usb_hub_wq hub_event schedule rpm_resume __pm_runtime_resume usb_autopm_get_interface usbnet_read_cmd __smsc95xx_read_reg __smsc95xx_phy_wait_not_busy __smsc95xx_mdio_read smsc95xx_mdiobus_read __mdiobus_read mdiobus_read smsc_phy_reset phy_init_hw smsc95xx_resume usb_resume_interface usb_resume_both usb_runtime_resume __rpm_callback rpm_callback rpm_resume __pm_runtime_resume usb_autoresume_device hub_event process_one_work
Fixes: b4df480f68ae ("usbnet: smsc95xx: add reset_resume function with reset operation") Signed-off-by: Lukas Wunner lukas@wunner.de Cc: stable@vger.kernel.org # v3.16+ Cc: Andre Edich andre.edich@microchip.com Signed-off-by: David S. Miller davem@davemloft.net
diff --git a/drivers/net/usb/smsc95xx.c b/drivers/net/usb/smsc95xx.c index 35110814ba22..0316c80c3fc4 100644 --- a/drivers/net/usb/smsc95xx.c +++ b/drivers/net/usb/smsc95xx.c @@ -71,6 +71,7 @@ struct smsc95xx_priv { struct fwnode_handle *irqfwnode; struct mii_bus *mdiobus; struct phy_device *phydev; + struct task_struct *pm_task; };
static bool turbo_mode = true; @@ -80,13 +81,14 @@ MODULE_PARM_DESC(turbo_mode, "Enable multiple frames per Rx transaction"); static int __must_check __smsc95xx_read_reg(struct usbnet *dev, u32 index, u32 *data, int in_pm) { + struct smsc95xx_priv *pdata = dev->driver_priv; u32 buf; int ret; int (*fn)(struct usbnet *, u8, u8, u16, u16, void *, u16);
BUG_ON(!dev);
- if (!in_pm) + if (current != pdata->pm_task) fn = usbnet_read_cmd; else fn = usbnet_read_cmd_nopm; @@ -110,13 +112,14 @@ 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) { + struct smsc95xx_priv *pdata = dev->driver_priv; u32 buf; int ret; int (*fn)(struct usbnet *, u8, u8, u16, u16, const void *, u16);
BUG_ON(!dev);
- if (!in_pm) + if (current != pdata->pm_task) fn = usbnet_write_cmd; else fn = usbnet_write_cmd_nopm; @@ -1490,9 +1493,12 @@ static int smsc95xx_suspend(struct usb_interface *intf, pm_message_t message) u32 val, link_up; int ret;
+ pdata->pm_task = current; + ret = usbnet_suspend(intf, message); if (ret < 0) { netdev_warn(dev->net, "usbnet_suspend error\n"); + pdata->pm_task = NULL; return ret; }
@@ -1732,6 +1738,7 @@ static int smsc95xx_suspend(struct usb_interface *intf, pm_message_t message) if (ret && PMSG_IS_AUTO(message)) usbnet_resume(intf);
+ pdata->pm_task = NULL; return ret; }
@@ -1752,29 +1759,31 @@ static int smsc95xx_resume(struct usb_interface *intf) /* do this first to ensure it's cleared even in error case */ pdata->suspend_flags = 0;
+ pdata->pm_task = current; + if (suspend_flags & SUSPEND_ALLMODES) { /* clear wake-up sources */ ret = smsc95xx_read_reg_nopm(dev, WUCSR, &val); if (ret < 0) - return ret; + goto done;
val &= ~(WUCSR_WAKE_EN_ | WUCSR_MPEN_);
ret = smsc95xx_write_reg_nopm(dev, WUCSR, val); if (ret < 0) - return ret; + goto done;
/* clear wake-up status */ ret = smsc95xx_read_reg_nopm(dev, PM_CTRL, &val); if (ret < 0) - return ret; + goto done;
val &= ~PM_CTL_WOL_EN_; val |= PM_CTL_WUPS_;
ret = smsc95xx_write_reg_nopm(dev, PM_CTRL, val); if (ret < 0) - return ret; + goto done; }
phy_init_hw(pdata->phydev); @@ -1783,15 +1792,20 @@ static int smsc95xx_resume(struct usb_interface *intf) if (ret < 0) netdev_warn(dev->net, "usbnet_resume error\n");
+done: + pdata->pm_task = NULL; return ret; }
static int smsc95xx_reset_resume(struct usb_interface *intf) { struct usbnet *dev = usb_get_intfdata(intf); + struct smsc95xx_priv *pdata = dev->driver_priv; int ret;
+ pdata->pm_task = current; ret = smsc95xx_reset(dev); + pdata->pm_task = NULL; if (ret < 0) return ret;