USB: EHCI: fix up locking

This patch (as1588) adjusts the locking in ehci-hcd's various halt,
shutdown, and suspend/resume pathways.  We want to hold the spinlock
while writing device registers and accessing shared variables, but not
while polling in a loop.

In addition, there's no need to call ehci_work() at times when no URBs
can be active, i.e., in ehci_stop() and ehci_bus_suspend().

Finally, ehci_adjust_port_wakeup_flags() is called only in situations
where interrupts are enabled; therefore it can use spin_lock_irq
rather than spin_lock_irqsave.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 33 insertions, 15 deletions

diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index 340c9c4894bf..ac4c8ddde20a 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -167,21 +167,24 @@ static int tdi_in_host_mode (struct ehci_hcd *ehci)
         return (tmp & 3) == USBMODE_CM_HC;
 }
 
-/* force HC to halt state from unknown (EHCI spec section 2.3) */
+/*
+ * Force HC to halt state from unknown (EHCI spec section 2.3).
+ * Must be called with interrupts enabled and the lock not held.
+ */
 static int ehci_halt (struct ehci_hcd *ehci)
 {
-        u32     temp = ehci_readl(ehci, &ehci->regs->status);
+        u32     temp;
+
+        spin_lock_irq(&ehci->lock);
 
         /* disable any irqs left enabled by previous code */
         ehci_writel(ehci, 0, &ehci->regs->intr_enable);
 
-        if (ehci_is_TDI(ehci) && tdi_in_host_mode(ehci) == 0) {
+        if (ehci_is_TDI(ehci) && !tdi_in_host_mode(ehci)) {
+                spin_unlock_irq(&ehci->lock);
                 return 0;
         }
 
-        if ((temp & STS_HALT) != 0)
-                return 0;
-
         /*
          * This routine gets called during probe before ehci->command
          * has been initialized, so we can't rely on its value.
@@ -190,7 +193,11 @@ static int ehci_halt (struct ehci_hcd *ehci)
         temp = ehci_readl(ehci, &ehci->regs->command);
         temp &= ~(CMD_RUN | CMD_IAAD);
         ehci_writel(ehci, temp, &ehci->regs->command);
-        return handshake (ehci, &ehci->regs->status,
+
+        spin_unlock_irq(&ehci->lock);
+        synchronize_irq(ehci_to_hcd(ehci)->irq);
+
+        return handshake(ehci, &ehci->regs->status,
                           STS_HALT, STS_HALT, 16 * 125);
 }
 
@@ -210,7 +217,10 @@ static void tdi_reset (struct ehci_hcd *ehci)
         ehci_writel(ehci, tmp, &ehci->regs->usbmode);
 }
 
-/* reset a non-running (STS_HALT == 1) controller */
+/*
+ * Reset a non-running (STS_HALT == 1) controller.
+ * Must be called with interrupts enabled and the lock not held.
+ */
 static int ehci_reset (struct ehci_hcd *ehci)
 {
         int     retval;
@@ -248,7 +258,10 @@ static int ehci_reset (struct ehci_hcd *ehci)
         return retval;
 }
 
-/* idle the controller (from running) */
+/*
+ * Idle the controller (turn off the schedules).
+ * Must be called with interrupts enabled and the lock not held.
+ */
 static void ehci_quiesce (struct ehci_hcd *ehci)
 {
         u32     temp;
@@ -261,8 +274,10 @@ static void ehci_quiesce (struct ehci_hcd *ehci)
         handshake(ehci, &ehci->regs->status, STS_ASS | STS_PSS, temp, 16 * 125);
 
         /* then disable anything that's still active */
+        spin_lock_irq(&ehci->lock);
         ehci->command &= ~(CMD_ASE | CMD_PSE);
         ehci_writel(ehci, ehci->command, &ehci->regs->command);
+        spin_unlock_irq(&ehci->lock);
 
         /* hardware can take 16 microframes to turn off ... */
         handshake(ehci, &ehci->regs->status, STS_ASS | STS_PSS, 0, 16 * 125);
@@ -301,11 +316,14 @@ static void ehci_turn_off_all_ports(struct ehci_hcd *ehci)
 
 /*
  * Halt HC, turn off all ports, and let the BIOS use the companion controllers.
- * Should be called with ehci->lock held.
+ * Must be called with interrupts enabled and the lock not held.
  */
 static void ehci_silence_controller(struct ehci_hcd *ehci)
 {
         ehci_halt(ehci);
+
+        spin_lock_irq(&ehci->lock);
+        ehci->rh_state = EHCI_RH_HALTED;
         ehci_turn_off_all_ports(ehci);
 
         /* make BIOS/etc use companion controller during reboot */
@@ -313,6 +331,7 @@ static void ehci_silence_controller(struct ehci_hcd *ehci)
 
         /* unblock posted writes */
         ehci_readl(ehci, &ehci->regs->configured_flag);
+        spin_unlock_irq(&ehci->lock);
 }
 
 /* ehci_shutdown kick in for silicon on any bus (not just pci, etc).
@@ -325,10 +344,11 @@ static void ehci_shutdown(struct usb_hcd *hcd)
 
         spin_lock_irq(&ehci->lock);
         ehci->rh_state = EHCI_RH_STOPPING;
-        ehci_silence_controller(ehci);
         ehci->enabled_hrtimer_events = 0;
         spin_unlock_irq(&ehci->lock);
 
+        ehci_silence_controller(ehci);
+
         hrtimer_cancel(&ehci->hrtimer);
 }
 
@@ -400,11 +420,11 @@ static void ehci_stop (struct usb_hcd *hcd)
 
         spin_lock_irq(&ehci->lock);
         ehci->enabled_hrtimer_events = 0;
-        ehci_quiesce(ehci);
+        spin_unlock_irq(&ehci->lock);
 
+        ehci_quiesce(ehci);
         ehci_silence_controller(ehci);
         ehci_reset (ehci);
-        spin_unlock_irq(&ehci->lock);
 
         hrtimer_cancel(&ehci->hrtimer);
         remove_sysfs_files(ehci);
@@ -412,8 +432,6 @@ static void ehci_stop (struct usb_hcd *hcd)
 
         /* root hub is shut down separately (first, when possible) */
         spin_lock_irq (&ehci->lock);
-        if (ehci->async)
-                ehci_work (ehci);
         end_free_itds(ehci);
         spin_unlock_irq (&ehci->lock);
         ehci_mem_cleanup (ehci);