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);