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BACKPORT: usb: typec: tcpm: enforce ready state when queueing alt mode vdm

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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: 03eafcfb60 ("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>

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 <rdbabiera@google.com>
This commit is contained in:
RD Babiera
2024-04-23 20:23:57 +00:00
committed by Todd Kjos
parent 4be94a6b03
commit ee016b98b7
1 changed files with 4 additions and 0 deletions
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4
drivers/usb/typec/tcpm/tcpm.c
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@@ -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);