[char-misc 1/2 for 4.11] mei: fix deadlock on mei reset

[char-misc 1/2 for 4.11] mei: fix deadlock on mei reset

[Tomas Winkler]

This patch fixes 'mei: synchronize irq before initiating a reset'
The patch had introduced a deadlock between irq thread and mei_reset()
as they are both holding the same device lock.

---> device_lock:
	mei_reset()
                        <---- interrupt thread
	                        device_lock
---> synchornize_irq()
       wait on interrupt thread == (dead lock)

The fix is to call synchronize_irq
prior to call locked mei_reset function.

Cc: <stable@vger.kernel.org> #4.10+
Fixes: f302bb0de6ac (mei: synchronize irq before initiating a reset)
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
---
 drivers/misc/mei/init.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/misc/mei/init.c b/drivers/misc/mei/init.c
index cfb1cdf176fa..13c55b8f9261 100644
--- a/drivers/misc/mei/init.c
+++ b/drivers/misc/mei/init.c
@@ -124,8 +124,6 @@ int mei_reset(struct mei_device *dev)
 
 	mei_clear_interrupts(dev);
 
-	mei_synchronize_irq(dev);
-
 	/* we're already in reset, cancel the init timer
 	 * if the reset was called due the hbm protocol error
 	 * we need to call it before hw start
@@ -304,6 +302,9 @@ static void mei_reset_work(struct work_struct *work)
 		container_of(work, struct mei_device,  reset_work);
 	int ret;
 
+	mei_clear_interrupts(dev);
+	mei_synchronize_irq(dev);
+
 	mutex_lock(&dev->device_lock);
 
 	ret = mei_reset(dev);
@@ -328,6 +329,9 @@ void mei_stop(struct mei_device *dev)
 
 	mei_cancel_work(dev);
 
+	mei_clear_interrupts(dev);
+	mei_synchronize_irq(dev);
+
 	mutex_lock(&dev->device_lock);
 
 	dev->dev_state = MEI_DEV_POWER_DOWN;
-- 
2.7.4

[char-misc 2/2 for 4.11] mei: don't wait for os version message reply

[Tomas Winkler]

From: Alexander Usyskin <alexander.usyskin@intel.com>

The driver still struggles with firmwares that do not replay to the OS
version request. It is safe not waiting for the replay. First, the driver
doesn't do anything with the replay second the connection is closed
immediately, hence the packet will be just safely discarded in case it
is received and last the driver won't get stuck if the firmware won't
reply.

Cc: <stable@vger.kernel.org> #4.10+
Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
---
 drivers/misc/mei/bus-fixup.c | 14 ++------------
 1 file changed, 2 insertions(+), 12 deletions(-)

diff --git a/drivers/misc/mei/bus-fixup.c b/drivers/misc/mei/bus-fixup.c
index 3600c9993a98..29f2daed37e0 100644
--- a/drivers/misc/mei/bus-fixup.c
+++ b/drivers/misc/mei/bus-fixup.c
@@ -112,11 +112,9 @@ struct mkhi_msg {
 
 static int mei_osver(struct mei_cl_device *cldev)
 {
-	int ret;
 	const size_t size = sizeof(struct mkhi_msg_hdr) +
 			    sizeof(struct mkhi_fwcaps) +
 			    sizeof(struct mei_os_ver);
-	size_t length = 8;
 	char buf[size];
 	struct mkhi_msg *req;
 	struct mkhi_fwcaps *fwcaps;
@@ -137,15 +135,7 @@ static int mei_osver(struct mei_cl_device *cldev)
 	os_ver = (struct mei_os_ver *)fwcaps->data;
 	os_ver->os_type = OSTYPE_LINUX;
 
-	ret = __mei_cl_send(cldev->cl, buf, size, mode);
-	if (ret < 0)
-		return ret;
-
-	ret = __mei_cl_recv(cldev->cl, buf, length, 0);
-	if (ret < 0)
-		return ret;
-
-	return 0;
+	return __mei_cl_send(cldev->cl, buf, size, mode);
 }
 
 static void mei_mkhi_fix(struct mei_cl_device *cldev)
@@ -160,7 +150,7 @@ static void mei_mkhi_fix(struct mei_cl_device *cldev)
 		return;
 
 	ret = mei_osver(cldev);
-	if (ret)
+	if (ret < 0)
 		dev_err(&cldev->dev, "OS version command failed %d\n", ret);
 
 	mei_cldev_disable(cldev);
-- 
2.7.4