Merge tag 'isci-for-3.5' into misc

isci update for 3.5

1/ Rework remote-node-context (RNC) handling for proper management of
   the silicon state machine in error handling and hot-plug conditions.
   Further details below, suffice to say if the RNC is mismanaged the
   silicon state machines may lock up.

2/ Refactor the initialization code to be reused for suspend/resume support

3/ Miscellaneous bug fixes to address discovery issues and hardware
   compatibility.

RNC rework details from Jeff Skirvin:

In the controller, devices as they appear on a SAS domain (or
direct-attached SATA devices) are represented by memory structures known
as "Remote Node Contexts" (RNCs).  These structures are transferred from
main memory to the controller using a set of register commands; these
commands include setting up the context ("posting"), removing the
context ("invalidating"), and commands to control the scheduling of
commands and connections to that remote device ("suspensions" and
"resumptions").  There is a similar path to control RNC scheduling from
the protocol engine, which interprets the results of command and data
transmission and reception.

In general, the controller chooses among non-suspended RNCs to find one
that has work requiring scheduling the transmission of command and data
frames to a target.  Likewise, when a target tries to return data back
to the initiator, the state of the RNC is used by the controller to
determine how to treat the incoming request. As an example, if the RNC
is in the state "TX/RX Suspended", incoming SSP connection requests from
the target will be rejected by the controller hardware.  When an RNC is
"TX Suspended", it will not be selected by the controller hardware to
start outgoing command or data operations (with certain priority-based
exceptions).

As mentioned above, there are two sources for management of the RNC
states: commands from driver software, and the result of transmission
and reception conditions of commands and data signaled by the controller
hardware.  As an example of the latter, if an outgoing SSP command ends
with a OPEN_REJECT(BAD_DESTINATION) status, the RNC state will
transition to the "TX Suspended" state, and this is signaled by the
controller hardware in the status to the completion of the pending
command as well as signaled in a controller hardware event.  Examples of
the former are included in the patch changelogs.

Driver software is required to suspend the RNC in a "TX/RX Suspended"
condition before any outstanding commands can be terminated.  Failure to
guarantee this can lead to a complete hardware hang condition.  Earlier
versions of the driver software did not guarantee that an RNC was
correctly managed before I/O termination, and so operated in an unsafe
way.

Further, the driver performed unnecessary contortions to preserve the
remote device command state and so was more complicated than it needed
to be.  A simplifying driver assumption is that once an I/O has entered
the error handler path without having completed in the target, the
requirement on the driver is that all use of the sas_task must end.
Beyond that, recovery of operation is dependent on libsas and other
components to reset, rediscover and reconfigure the device before normal
operation can restart.  In the driver, this simplifying assumption meant
that the RNC management could be reduced to entry into the suspended
state, terminating the targeted I/O request, and resuming the RNC as
needed for device-specific management such as an SSP Abort Task or LUN
Reset Management request.

1 files changed, 53 insertions, 16 deletions

diff --git a/drivers/xen/xenbus/xenbus_probe_frontend.c b/drivers/xen/xenbus/xenbus_probe_frontend.c
index f20c5f178b40..a31b54d48839 100644
--- a/drivers/xen/xenbus/xenbus_probe_frontend.c
+++ b/drivers/xen/xenbus/xenbus_probe_frontend.c
@@ -135,7 +135,7 @@ static int read_backend_details(struct xenbus_device *xendev)
 	return xenbus_read_otherend_details(xendev, "backend-id", "backend");
 }
 
-static int is_device_connecting(struct device *dev, void *data)
+static int is_device_connecting(struct device *dev, void *data, bool ignore_nonessential)
 {
 	struct xenbus_device *xendev = to_xenbus_device(dev);
 	struct device_driver *drv = data;
@@ -152,16 +152,41 @@ static int is_device_connecting(struct device *dev, void *data)
 	if (drv && (dev->driver != drv))
 		return 0;
 
+	if (ignore_nonessential) {
+		/* With older QEMU, for PVonHVM guests the guest config files
+		 * could contain: vfb = [ 'vnc=1, vnclisten=0.0.0.0']
+		 * which is nonsensical as there is no PV FB (there can be
+		 * a PVKB) running as HVM guest. */
+
+		if ((strncmp(xendev->nodename, "device/vkbd", 11) == 0))
+			return 0;
+
+		if ((strncmp(xendev->nodename, "device/vfb", 10) == 0))
+			return 0;
+	}
 	xendrv = to_xenbus_driver(dev->driver);
 	return (xendev->state < XenbusStateConnected ||
 		(xendev->state == XenbusStateConnected &&
 		 xendrv->is_ready && !xendrv->is_ready(xendev)));
 }
+static int essential_device_connecting(struct device *dev, void *data)
+{
+	return is_device_connecting(dev, data, true /* ignore PV[KBB+FB] */);
+}
+static int non_essential_device_connecting(struct device *dev, void *data)
+{
+	return is_device_connecting(dev, data, false);
+}
 
-static int exists_connecting_device(struct device_driver *drv)
+static int exists_essential_connecting_device(struct device_driver *drv)
 {
 	return bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
-				is_device_connecting);
+				essential_device_connecting);
+}
+static int exists_non_essential_connecting_device(struct device_driver *drv)
+{
+	return bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
+				non_essential_device_connecting);
 }
 
 static int print_device_status(struct device *dev, void *data)
@@ -192,6 +217,23 @@ static int print_device_status(struct device *dev, void *data)
 /* We only wait for device setup after most initcalls have run. */
 static int ready_to_wait_for_devices;
 
+static bool wait_loop(unsigned long start, unsigned int max_delay,
+		     unsigned int *seconds_waited)
+{
+	if (time_after(jiffies, start + (*seconds_waited+5)*HZ)) {
+		if (!*seconds_waited)
+			printk(KERN_WARNING "XENBUS: Waiting for "
+			       "devices to initialise: ");
+		*seconds_waited += 5;
+		printk("%us...", max_delay - *seconds_waited);
+		if (*seconds_waited == max_delay)
+			return true;
+	}
+
+	schedule_timeout_interruptible(HZ/10);
+
+	return false;
+}
 /*
  * On a 5-minute timeout, wait for all devices currently configured.  We need
  * to do this to guarantee that the filesystems and / or network devices
@@ -215,19 +257,14 @@ static void wait_for_devices(struct xenbus_driver *xendrv)
 	if (!ready_to_wait_for_devices || !xen_domain())
 		return;
 
-	while (exists_connecting_device(drv)) {
-		if (time_after(jiffies, start + (seconds_waited+5)*HZ)) {
-			if (!seconds_waited)
-				printk(KERN_WARNING "XENBUS: Waiting for "
-				       "devices to initialise: ");
-			seconds_waited += 5;
-			printk("%us...", 300 - seconds_waited);
-			if (seconds_waited == 300)
-				break;
-		}
-
-		schedule_timeout_interruptible(HZ/10);
-	}
+	while (exists_non_essential_connecting_device(drv))
+		if (wait_loop(start, 30, &seconds_waited))
+			break;
+
+	/* Skips PVKB and PVFB check.*/
+	while (exists_essential_connecting_device(drv))
+		if (wait_loop(start, 270, &seconds_waited))
+			break;
 
 	if (seconds_waited)
 		printk("\n");