FAILED: patch "[PATCH] usb: typec: tcpm: enforce ready state when queueing alt mode" failed to apply to 6.8-stable tree

FAILED: patch "[PATCH] usb: typec: tcpm: enforce ready state when queueing alt mode" failed to apply to 6.8-stable tree

[gregkh]

The patch below does not apply to the 6.8-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.8.y
git checkout FETCH_HEAD
git cherry-pick -x cdc9946ea6377e8e214b135ccc308c5e514ba25f
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2024051323-entering-curtly-c09a@gregkh' --subject-prefix 'PATCH 6.8.y' HEAD^..

Possible dependencies:

cdc9946ea637 ("usb: typec: tcpm: enforce ready state when queueing alt mode vdm")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From cdc9946ea6377e8e214b135ccc308c5e514ba25f Mon Sep 17 00:00:00 2001
From: RD Babiera <rdbabiera@google.com>
Date: Tue, 23 Apr 2024 20:23:57 +0000
Subject: [PATCH] usb: typec: tcpm: enforce ready state when queueing alt mode
 vdm

Before sending Enter Mode for an Alt Mode, there is a gap between Discover
Modes and the Alt Mode driver queueing the Enter Mode VDM for the port
partner to send a message to the port.

If this message results in unregistering Alt Modes such as in a DR_SWAP,
then the following deadlock can occur with respect to the DisplayPort Alt
Mode driver:
1. The DR_SWAP state holds port->lock. Unregistering the Alt Mode driver
results in a cancel_work_sync() that waits for the current dp_altmode_work
to finish.
2. dp_altmode_work makes a call to tcpm_altmode_enter. The deadlock occurs
because tcpm_queue_vdm_unlock attempts to hold port->lock.

Before attempting to grab the lock, ensure that the port is in a state
vdm_run_state_machine can run in. Alt Mode unregistration will not occur
in these states.

Fixes: 03eafcfb60c0 ("usb: typec: tcpm: Add tcpm_queue_vdm_unlocked() helper")
Cc: stable@vger.kernel.org
Signed-off-by: RD Babiera <rdbabiera@google.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20240423202356.3372314-2-rdbabiera@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
index 77e632ea6872..53c1f308ebd7 100644
--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -1564,6 +1564,10 @@ static void tcpm_queue_vdm(struct tcpm_port *port, const u32 header,
 static void tcpm_queue_vdm_unlocked(struct tcpm_port *port, const u32 header,
 				    const u32 *data, int cnt, enum tcpm_transmit_type tx_sop_type)
 {
+	if (port->state != SRC_READY && port->state != SNK_READY &&
+	    port->state != SRC_VDM_IDENTITY_REQUEST)
+		return;
+
 	mutex_lock(&port->lock);
 	tcpm_queue_vdm(port, header, data, cnt, tx_sop_type);
 	mutex_unlock(&port->lock);