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[ Upstream commit08c487d8d8] When a netdev down event occurs after a successful call to j1939_sk_bind(), j1939_netdev_notify() can handle it correctly. But if the netdev already in down state before calling j1939_sk_bind(), j1939_sk_release() will stay in wait_event_interruptible() blocked forever. Because in this case, j1939_netdev_notify() won't be called and j1939_tp_txtimer() won't call j1939_session_cancel() or other function to clear session for ENETDOWN error, this lead to mismatch of j1939_session_get/put() and jsk->skb_pending will never decrease to zero. To reproduce it use following commands: 1. ip link add dev vcan0 type vcan 2. j1939acd -r 100,80-120 1122334455667788 vcan0 3. presses ctrl-c and thread will be blocked forever This patch adds check for ndev->flags in j1939_sk_bind() to avoid this kind of situation and return with -ENETDOWN. Fixes:9d71dd0c70("can: add support of SAE J1939 protocol") Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com> Link: https://lore.kernel.org/r/1599460308-18770-1-git-send-email-zhangchangzhong@huawei.com Acked-by: Oleksij Rempel <o.rempel@pengutronix.de> Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de> Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.