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[34.91.144.72]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-ae053edc0f5sm888265966b.59.2025.06.24.06.33.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 24 Jun 2025 06:33:04 -0700 (PDT) From: Andrei Kuchynski To: Heikki Krogerus , Jos Wang Cc: Greg Kroah-Hartman , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, Andrei Kuchynski , stable@vger.kernel.org Subject: [PATCH] usb: typec: displayport: Fix potential deadlock Date: Tue, 24 Jun 2025 13:32:46 +0000 Message-ID: <20250624133246.3936737-1-akuchynski@chromium.org> X-Mailer: git-send-email 2.50.0.rc2.761.g2dc52ea45b-goog Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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@vger.kernel.org Fixes: b4b38ffb38c9 ("usb: typec: displayport: Receive DP Status Update NAK= request exit dp altmode") Signed-off-by: Andrei Kuchynski Reviewed-by: Heikki Krogerus --- drivers/usb/typec/altmodes/displayport.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/drivers/usb/typec/altmodes/displayport.c b/drivers/usb/typec/a= ltmodes/displayport.c index b09b58d7311d..2abbe4de3216 100644 --- a/drivers/usb/typec/altmodes/displayport.c +++ b/drivers/usb/typec/altmodes/displayport.c @@ -394,8 +394,7 @@ 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 =3D DP_STATE_EXIT; break; case DP_CMD_CONFIGURE: dp->data.conf =3D 0; --=20 2.50.0.rc2.761.g2dc52ea45b-goog