[PATCH] PM: prevent runtime_resume from racing with probe

[Alan Stern <stern@rowland.harvard.edu>]

This patch (as1475) adds device_lock() and device_unlock() calls to
the store methods for the power/control and power/autosuspend_delay_ms
sysfs attribute files.  We don't want badly timed writes to these
files to cause runtime_resume callbacks to occur while a driver is
being probed for a device.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>

---

 drivers/base/power/sysfs.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

Index: usb-3.0/drivers/base/power/sysfs.c
===================================================================
--- usb-3.0.orig/drivers/base/power/sysfs.c
+++ usb-3.0/drivers/base/power/sysfs.c
@@ -116,12 +116,14 @@ static ssize_t control_store(struct devi
 	cp = memchr(buf, '\n', n);
 	if (cp)
 		len = cp - buf;
+	device_lock(dev);
 	if (len == sizeof ctrl_auto - 1 && strncmp(buf, ctrl_auto, len) == 0)
 		pm_runtime_allow(dev);
 	else if (len == sizeof ctrl_on - 1 && strncmp(buf, ctrl_on, len) == 0)
 		pm_runtime_forbid(dev);
 	else
-		return -EINVAL;
+		n = -EINVAL;
+	device_unlock(dev);
 	return n;
 }
 
@@ -205,7 +207,9 @@ static ssize_t autosuspend_delay_ms_stor
 	if (strict_strtol(buf, 10, &delay) != 0 || delay != (int) delay)
 		return -EINVAL;
 
+	device_lock(dev);
 	pm_runtime_set_autosuspend_delay(dev, delay);
+	device_unlock(dev);
 	return n;
 }