linux-kernel - [char-misc-next 20/27] mei: discard replies from unconnected fixed address clients

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Message-Id: <1454880943-12653-21-git-send-email-tomas.winkler@intel.com>
Date:	Sun,  7 Feb 2016 23:35:36 +0200
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,
	Tomas Winkler <tomas.winkler@...el.com>
Subject: [char-misc-next 20/27] mei: discard replies from unconnected fixed address clients

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

A fixed address client in the FW doesn't have a notion of connection and
can send message after the file associated with it was already closed.
Silently discard such messages.
Add inline helpers to detect whether a message is hbm or intended for
a fixed address client

Signed-off-by: Alexander Usyskin <alexander.usyskin@...el.com>
Signed-off-by: Tomas Winkler <tomas.winkler@...el.com>
---
 drivers/misc/mei/interrupt.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/drivers/misc/mei/interrupt.c b/drivers/misc/mei/interrupt.c
index 72806ef6efdd..06b744a503a3 100644
--- a/drivers/misc/mei/interrupt.c
+++ b/drivers/misc/mei/interrupt.c
@@ -239,6 +239,16 @@ static int mei_cl_irq_read(struct mei_cl *cl, struct mei_cl_cb *cb,
 	return 0;
 }
 
+static inline bool hdr_is_hbm(struct mei_msg_hdr *mei_hdr)
+{
+	return mei_hdr->host_addr == 0 && mei_hdr->me_addr == 0;
+}
+
+static inline bool hdr_is_fixed(struct mei_msg_hdr *mei_hdr)
+{
+	return mei_hdr->host_addr == 0 && mei_hdr->me_addr != 0;
+}
+
 /**
  * mei_irq_read_handler - bottom half read routine after ISR to
  * handle the read processing.
@@ -280,7 +290,7 @@ int mei_irq_read_handler(struct mei_device *dev,
 	}
 
 	/*  HBM message */
-	if (mei_hdr->host_addr == 0 && mei_hdr->me_addr == 0) {
+	if (hdr_is_hbm(mei_hdr)) {
 		ret = mei_hbm_dispatch(dev, mei_hdr);
 		if (ret) {
 			dev_dbg(dev->dev, "mei_hbm_dispatch failed ret = %d\n",
@@ -300,6 +310,14 @@ int mei_irq_read_handler(struct mei_device *dev,
 
 	/* if no recipient cl was found we assume corrupted header */
 	if (&cl->link == &dev->file_list) {
+		/* A message for not connected fixed address clients
+		 * should be silently discarded
+		 */
+		if (hdr_is_fixed(mei_hdr)) {
+			mei_irq_discard_msg(dev, mei_hdr);
+			ret = 0;
+			goto reset_slots;
+		}
 		dev_err(dev->dev, "no destination client found 0x%08X\n",
 				dev->rd_msg_hdr);
 		ret = -EBADMSG;
-- 
2.4.3