linux-kernel - [char-misc-next 3/3] mei: amthif: discard not read messages

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Date:	Sun, 17 Apr 2016 12:16:04 -0400
From:	Tomas Winkler <tomas.winkler@...el.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	Alexander Usyskin <alexander.usyskin@...el.com>,
	linux-kernel@...r.kernel.org, <stable@...r.kernel.org>,
	Tomas Winkler <tomas.winkler@...el.com>
Subject: [char-misc-next 3/3] mei: amthif: discard not read messages

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

When a message is received and amthif client is not in reading state
the message is ignored and left dangling in the queue. This may happen
after one of the amthif host connections is closed w/o completing the
reading. Another client will pick up a wrong message on next read
attempt which will lead to link reset.
To prevent this the driver has to properly discard the message when
amthif client is not in reading state.

Cc: <stable@...r.kernel.org> #4.2+
Signed-off-by: Alexander Usyskin <alexander.usyskin@...el.com>
Signed-off-by: Tomas Winkler <tomas.winkler@...el.com>
---
 drivers/misc/mei/amthif.c    | 4 +++-
 drivers/misc/mei/interrupt.c | 1 -
 drivers/misc/mei/mei_dev.h   | 2 ++
 3 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/misc/mei/amthif.c b/drivers/misc/mei/amthif.c
index 194360a5f782..a039a5df6f21 100644
--- a/drivers/misc/mei/amthif.c
+++ b/drivers/misc/mei/amthif.c
@@ -380,8 +380,10 @@ int mei_amthif_irq_read_msg(struct mei_cl *cl,
 
 	dev = cl->dev;
 
-	if (dev->iamthif_state != MEI_IAMTHIF_READING)
+	if (dev->iamthif_state != MEI_IAMTHIF_READING) {
+		mei_irq_discard_msg(dev, mei_hdr);
 		return 0;
+	}
 
 	ret = mei_cl_irq_read_msg(cl, mei_hdr, cmpl_list);
 	if (ret)
diff --git a/drivers/misc/mei/interrupt.c b/drivers/misc/mei/interrupt.c
index 704dc6caad6d..3831a7ba2531 100644
--- a/drivers/misc/mei/interrupt.c
+++ b/drivers/misc/mei/interrupt.c
@@ -76,7 +76,6 @@ static inline int mei_cl_hbm_equal(struct mei_cl *cl,
  * @dev: mei device
  * @hdr: message header
  */
-static inline
 void mei_irq_discard_msg(struct mei_device *dev, struct mei_msg_hdr *hdr)
 {
 	/*
diff --git a/drivers/misc/mei/mei_dev.h b/drivers/misc/mei/mei_dev.h
index 87586bbc4a41..c9e01021eadf 100644
--- a/drivers/misc/mei/mei_dev.h
+++ b/drivers/misc/mei/mei_dev.h
@@ -702,6 +702,8 @@ bool mei_hbuf_acquire(struct mei_device *dev);
 
 bool mei_write_is_idle(struct mei_device *dev);
 
+void mei_irq_discard_msg(struct mei_device *dev, struct mei_msg_hdr *hdr);
+
 #if IS_ENABLED(CONFIG_DEBUG_FS)
 int mei_dbgfs_register(struct mei_device *dev, const char *name);
 void mei_dbgfs_deregister(struct mei_device *dev);
-- 
2.5.5