From ee016b98b7fa37c8b5fdb83bca854ad2e1057d07 Mon Sep 17 00:00:00 2001 From: RD Babiera Date: Tue, 23 Apr 2024 20:23:57 +0000 Subject: [PATCH] BACKPORT: 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 Reviewed-by: Heikki Krogerus Link: https://lore.kernel.org/r/20240423202356.3372314-2-rdbabiera@google.com Signed-off-by: Greg Kroah-Hartman Bug: 416695677 [rd: removed SRC_VDM_IDENTITY_REQUEST check, state not defined in branch] (cherry picked from commit cdc9946ea6377e8e214b135ccc308c5e514ba25f) Change-Id: Ie35bfd7a653a1cf892d64bb9b9f0d4dbd01e91c2 Signed-off-by: RD Babiera --- 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 25d4b451f393..78f929e53335 100644 --- a/drivers/usb/typec/tcpm/tcpm.c +++ b/drivers/usb/typec/tcpm/tcpm.c @@ -1534,6 +1534,10 @@ 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) { + 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); mutex_unlock(&port->lock);