e1000e: do not ever sleep in interrupt context

e1000e was apparently calling two functions that attempted to reserve
the SWFLAG bit for exclusive (to hardware and firmware) access to
the PHY and NVM (aka eeprom).  These accesses could possibly call
msleep to wait for the resource which is not allowed from interrupt
context.

Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/net/e1000e/netdev.c b/drivers/net/e1000e/netdev.c
index 1f767fe..803545b 100644
--- a/drivers/net/e1000e/netdev.c
+++ b/drivers/net/e1000e/netdev.c
@@ -1115,6 +1115,14 @@
 	writel(0, adapter->hw.hw_addr + rx_ring->tail);
 }
 
+static void e1000e_downshift_workaround(struct work_struct *work)
+{
+	struct e1000_adapter *adapter = container_of(work,
+					struct e1000_adapter, downshift_task);
+
+	e1000e_gig_downshift_workaround_ich8lan(&adapter->hw);
+}
+
 /**
  * e1000_intr_msi - Interrupt Handler
  * @irq: interrupt number
@@ -1139,7 +1147,7 @@
 		 */
 		if ((adapter->flags & FLAG_LSC_GIG_SPEED_DROP) &&
 		    (!(er32(STATUS) & E1000_STATUS_LU)))
-			e1000e_gig_downshift_workaround_ich8lan(hw);
+			schedule_work(&adapter->downshift_task);
 
 		/*
 		 * 80003ES2LAN workaround-- For packet buffer work-around on
@@ -1205,7 +1213,7 @@
 		 */
 		if ((adapter->flags & FLAG_LSC_GIG_SPEED_DROP) &&
 		    (!(er32(STATUS) & E1000_STATUS_LU)))
-			e1000e_gig_downshift_workaround_ich8lan(hw);
+			schedule_work(&adapter->downshift_task);
 
 		/*
 		 * 80003ES2LAN workaround--
@@ -2912,6 +2920,21 @@
 	return 0;
 }
 
+/**
+ * e1000e_update_phy_task - work thread to update phy
+ * @work: pointer to our work struct
+ *
+ * this worker thread exists because we must acquire a
+ * semaphore to read the phy, which we could msleep while
+ * waiting for it, and we can't msleep in a timer.
+ **/
+static void e1000e_update_phy_task(struct work_struct *work)
+{
+	struct e1000_adapter *adapter = container_of(work,
+					struct e1000_adapter, update_phy_task);
+	e1000_get_phy_info(&adapter->hw);
+}
+
 /*
  * Need to wait a few seconds after link up to get diagnostic information from
  * the phy
@@ -2919,7 +2942,7 @@
 static void e1000_update_phy_info(unsigned long data)
 {
 	struct e1000_adapter *adapter = (struct e1000_adapter *) data;
-	e1000_get_phy_info(&adapter->hw);
+	schedule_work(&adapter->update_phy_task);
 }
 
 /**
@@ -4578,6 +4601,8 @@
 
 	INIT_WORK(&adapter->reset_task, e1000_reset_task);
 	INIT_WORK(&adapter->watchdog_task, e1000_watchdog_task);
+	INIT_WORK(&adapter->downshift_task, e1000e_downshift_workaround);
+	INIT_WORK(&adapter->update_phy_task, e1000e_update_phy_task);
 
 	/* Initialize link parameters. User can change them with ethtool */
 	adapter->hw.mac.autoneg = 1;