[char-misc-next 2/3] mei: don't get stack in select during reset

[Tomas Winkler <tomas.winkler@intel.com>]

Clear pending connection after hw reset but before hw start
and wake up the waiting task in poll. Signal POLLERR in select
when device went through reset.

Add wrapper mei_cl_is_connected for checking if
the device and client are connected.

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
---
 drivers/misc/mei/amthif.c | 14 +++++++++++---
 drivers/misc/mei/client.c |  5 +----
 drivers/misc/mei/client.h |  7 +++++++
 drivers/misc/mei/init.c   | 13 ++++++++-----
 drivers/misc/mei/main.c   | 22 +++++++++++++++-------
 5 files changed, 42 insertions(+), 19 deletions(-)

diff --git a/drivers/misc/mei/amthif.c b/drivers/misc/mei/amthif.c
index 749452f..d0fdc13 100644
--- a/drivers/misc/mei/amthif.c
+++ b/drivers/misc/mei/amthif.c
@@ -418,15 +418,23 @@ unsigned int mei_amthif_poll(struct mei_device *dev,
 		struct file *file, poll_table *wait)
 {
 	unsigned int mask = 0;
-	mutex_unlock(&dev->device_lock);
+
 	poll_wait(file, &dev->iamthif_cl.wait, wait);
+
 	mutex_lock(&dev->device_lock);
-	if (dev->iamthif_state == MEI_IAMTHIF_READ_COMPLETE &&
-		dev->iamthif_file_object == file) {
+	if (!mei_cl_is_connected(&dev->iamthif_cl)) {
+
+		mask = POLLERR;
+
+	} else if (dev->iamthif_state == MEI_IAMTHIF_READ_COMPLETE &&
+		   dev->iamthif_file_object == file) {
+
 		mask |= (POLLIN | POLLRDNORM);
 		dev_dbg(&dev->pdev->dev, "run next amthif cb\n");
 		mei_amthif_run_next_cmd(dev);
 	}
+	mutex_unlock(&dev->device_lock);
+
 	return mask;
 }
 
diff --git a/drivers/misc/mei/client.c b/drivers/misc/mei/client.c
index af1e602..e0684b4 100644
--- a/drivers/misc/mei/client.c
+++ b/drivers/misc/mei/client.c
@@ -635,10 +635,7 @@ int mei_cl_read_start(struct mei_cl *cl, size_t length)
 
 	dev = cl->dev;
 
-	if (cl->state != MEI_FILE_CONNECTED)
-		return -ENODEV;
-
-	if (dev->dev_state != MEI_DEV_ENABLED)
+	if (!mei_cl_is_connected(cl))
 		return -ENODEV;
 
 	if (cl->read_cb) {
diff --git a/drivers/misc/mei/client.h b/drivers/misc/mei/client.h
index 9bae4c7..9eb031e 100644
--- a/drivers/misc/mei/client.h
+++ b/drivers/misc/mei/client.h
@@ -84,6 +84,13 @@ int mei_cl_flow_ctrl_reduce(struct mei_cl *cl);
 /*
  *  MEI input output function prototype
  */
+static inline bool mei_cl_is_connected(struct mei_cl *cl)
+{
+	return (cl->dev &&
+		cl->dev->dev_state == MEI_DEV_ENABLED &&
+		cl->state == MEI_FILE_CONNECTED);
+}
+
 bool mei_cl_is_other_connecting(struct mei_cl *cl);
 int mei_cl_disconnect(struct mei_cl *cl);
 int mei_cl_connect(struct mei_cl *cl, struct file *file);
diff --git a/drivers/misc/mei/init.c b/drivers/misc/mei/init.c
index 4bb7f3c..e38e3d89 100644
--- a/drivers/misc/mei/init.c
+++ b/drivers/misc/mei/init.c
@@ -150,12 +150,20 @@ void mei_reset(struct mei_device *dev, int interrupts_enabled)
 
 	if (dev->dev_state != MEI_DEV_INITIALIZING &&
 	    dev->dev_state != MEI_DEV_POWER_UP) {
+
 		if (dev->dev_state != MEI_DEV_DISABLED &&
 		    dev->dev_state != MEI_DEV_POWER_DOWN)
 			dev->dev_state = MEI_DEV_RESETTING;
 
+
+		/* remove all waiting requests */
+		mei_cl_all_write_clear(dev);
+
 		mei_cl_all_disconnect(dev);
 
+		/* wake up all readings so they can be interrupted */
+		mei_cl_all_wakeup(dev);
+
 		/* remove entry if already in list */
 		dev_dbg(&dev->pdev->dev, "remove iamthif and wd from the file list.\n");
 		mei_cl_unlink(&dev->wd_cl);
@@ -196,11 +204,6 @@ void mei_reset(struct mei_device *dev, int interrupts_enabled)
 
 	mei_hbm_start_req(dev);
 
-	/* wake up all readings so they can be interrupted */
-	mei_cl_all_wakeup(dev);
-
-	/* remove all waiting requests */
-	mei_cl_all_write_clear(dev);
 }
 EXPORT_SYMBOL_GPL(mei_reset);
 
diff --git a/drivers/misc/mei/main.c b/drivers/misc/mei/main.c
index 5e11b5b..173ff09 100644
--- a/drivers/misc/mei/main.c
+++ b/drivers/misc/mei/main.c
@@ -625,24 +625,32 @@ static unsigned int mei_poll(struct file *file, poll_table *wait)
 	unsigned int mask = 0;
 
 	if (WARN_ON(!cl || !cl->dev))
-		return mask;
+		return POLLERR;
 
 	dev = cl->dev;
 
 	mutex_lock(&dev->device_lock);
 
-	if (dev->dev_state != MEI_DEV_ENABLED)
-		goto out;
-
-
-	if (cl == &dev->iamthif_cl) {
-		mask = mei_amthif_poll(dev, file, wait);
+	if (!mei_cl_is_connected(cl)) {
+		mask = POLLERR;
 		goto out;
 	}
 
 	mutex_unlock(&dev->device_lock);
+
+
+	if (cl == &dev->iamthif_cl)
+		return mei_amthif_poll(dev, file, wait);
+
 	poll_wait(file, &cl->tx_wait, wait);
+
 	mutex_lock(&dev->device_lock);
+
+	if (!mei_cl_is_connected(cl)) {
+		mask = POLLERR;
+		goto out;
+	}
+
 	if (MEI_WRITE_COMPLETE == cl->writing_state)
 		mask |= (POLLIN | POLLRDNORM);
 
-- 
1.8.1.2