From: RD Babiera <rdbabiera@google.com>
To: linux@roeck-us.net, heikki.krogerus@linux.intel.com,
gregkh@linuxfoundation.org, hdegoede@redhat.com
Cc: badhri@google.com, linux-usb@vger.kernel.org,
linux-kernel@vger.kernel.org, RD Babiera <rdbabiera@google.com>,
stable@vger.kernel.org
Subject: [PATCH v1] usb: typec: tcpm: enforce ready state when queueing alt mode vdm
Date: Tue, 23 Apr 2024 20:23:57 +0000 [thread overview]
Message-ID: <20240423202356.3372314-2-rdbabiera@google.com> (raw)
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>
---
drivers/usb/typec/tcpm/tcpm.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
index c26fb70c3ec6..6fa1601ac259 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, TCPC_TX_SOP);
mutex_unlock(&port->lock);
base-commit: 684e9f5f97eb4b7831298ffad140d5c1d426ff27
--
2.44.0.769.g3c40516874-goog
next reply other threads:[~2024-04-23 20:25 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-23 20:23 RD Babiera [this message]
2024-04-25 9:49 ` [PATCH v1] usb: typec: tcpm: enforce ready state when queueing alt mode vdm Heikki Krogerus
2024-04-25 17:37 ` RD Babiera
2024-04-29 8:18 ` Heikki Krogerus
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