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usb: typec: displayport: Fix potential deadlock

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commit 099cf1fbb8afc3771f408109f62bdec66f85160e upstream.

The deadlock can occur due to a recursive lock acquisition of
`cros_typec_altmode_data::mutex`.
The call chain is as follows:
1. cros_typec_altmode_work() acquires the mutex
2. typec_altmode_vdm() -> dp_altmode_vdm() ->
3. typec_altmode_exit() -> cros_typec_altmode_exit()
4. cros_typec_altmode_exit() attempts to acquire the mutex again

To prevent this, defer the `typec_altmode_exit()` call by scheduling
it rather than calling it directly from within the mutex-protected
context.

Cc: stable <stable@kernel.org>
Fixes: b4b38ffb38c9 ("usb: typec: displayport: Receive DP Status Update NAK request exit dp altmode")
Signed-off-by: Andrei Kuchynski <akuchynski@chromium.org>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20250624133246.3936737-1-akuchynski@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Andrei Kuchynski
2025-06-24 13:32:46 +00:00
committed by Greg Kroah-Hartman
parent 4b91b77af2
commit 63cff9f57e
1 changed files with 1 additions and 2 deletions
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3
drivers/usb/typec/altmodes/displayport.c
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@@ -324,8 +324,7 @@ static int dp_altmode_vdm(struct typec_altmode *alt,
case CMDT_RSP_NAK:
switch (cmd) {
case DP_CMD_STATUS_UPDATE:
if (typec_altmode_exit(alt))
dev_err(&dp->alt->dev, "Exit Mode Failed!\n");
dp->state = DP_STATE_EXIT;
break;
case DP_CMD_CONFIGURE:
dp->data.conf = 0;