linux-kernel - [PATCH 4.18 058/150] thunderbolt: Do not handle ICM events after domain is stopped

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Date:   Fri,  2 Nov 2018 19:33:40 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.18 058/150] thunderbolt: Do not handle ICM events after domain is stopped

4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit 86da809dda64a63fc27e05a215475325c3aaae92 ]

If there is a long chain of devices connected when the driver is loaded
ICM sends device connected event for each and those are put to tb->wq
for later processing. Now if the driver gets unloaded in the middle, so
that the work queue is not yet empty it gets flushed by tb_domain_stop().
However, by that time the root switch is already removed so the driver
crashes when it tries to dereference it in ICM event handling callbacks.

Fix this by checking whether the root switch is already removed. If it
is we know that the domain is stopped and we should merely skip handling
the event.

Signed-off-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/thunderbolt/icm.c | 49 ++++++++++++++++-----------------------
 1 file changed, 20 insertions(+), 29 deletions(-)

diff --git a/drivers/thunderbolt/icm.c b/drivers/thunderbolt/icm.c
index 500911f16498..5bad9fdec5f8 100644
--- a/drivers/thunderbolt/icm.c
+++ b/drivers/thunderbolt/icm.c
@@ -653,14 +653,6 @@ icm_fr_xdomain_connected(struct tb *tb, const struct icm_pkg_header *hdr)
 	bool approved;
 	u64 route;
 
-	/*
-	 * After NVM upgrade adding root switch device fails because we
-	 * initiated reset. During that time ICM might still send
-	 * XDomain connected message which we ignore here.
-	 */
-	if (!tb->root_switch)
-		return;
-
 	link = pkg->link_info & ICM_LINK_INFO_LINK_MASK;
 	depth = (pkg->link_info & ICM_LINK_INFO_DEPTH_MASK) >>
 		ICM_LINK_INFO_DEPTH_SHIFT;
@@ -950,14 +942,6 @@ icm_tr_device_connected(struct tb *tb, const struct icm_pkg_header *hdr)
 	if (pkg->hdr.packet_id)
 		return;
 
-	/*
-	 * After NVM upgrade adding root switch device fails because we
-	 * initiated reset. During that time ICM might still send device
-	 * connected message which we ignore here.
-	 */
-	if (!tb->root_switch)
-		return;
-
 	route = get_route(pkg->route_hi, pkg->route_lo);
 	authorized = pkg->link_info & ICM_LINK_INFO_APPROVED;
 	security_level = (pkg->hdr.flags & ICM_FLAGS_SLEVEL_MASK) >>
@@ -1317,19 +1301,26 @@ static void icm_handle_notification(struct work_struct *work)
 
 	mutex_lock(&tb->lock);
 
-	switch (n->pkg->code) {
-	case ICM_EVENT_DEVICE_CONNECTED:
-		icm->device_connected(tb, n->pkg);
-		break;
-	case ICM_EVENT_DEVICE_DISCONNECTED:
-		icm->device_disconnected(tb, n->pkg);
-		break;
-	case ICM_EVENT_XDOMAIN_CONNECTED:
-		icm->xdomain_connected(tb, n->pkg);
-		break;
-	case ICM_EVENT_XDOMAIN_DISCONNECTED:
-		icm->xdomain_disconnected(tb, n->pkg);
-		break;
+	/*
+	 * When the domain is stopped we flush its workqueue but before
+	 * that the root switch is removed. In that case we should treat
+	 * the queued events as being canceled.
+	 */
+	if (tb->root_switch) {
+		switch (n->pkg->code) {
+		case ICM_EVENT_DEVICE_CONNECTED:
+			icm->device_connected(tb, n->pkg);
+			break;
+		case ICM_EVENT_DEVICE_DISCONNECTED:
+			icm->device_disconnected(tb, n->pkg);
+			break;
+		case ICM_EVENT_XDOMAIN_CONNECTED:
+			icm->xdomain_connected(tb, n->pkg);
+			break;
+		case ICM_EVENT_XDOMAIN_DISCONNECTED:
+			icm->xdomain_disconnected(tb, n->pkg);
+			break;
+		}
 	}
 
 	mutex_unlock(&tb->lock);
-- 
2.17.1