tty: isicom: fix deadlock on shutdown
Alexander Strakh <strakh@ispras.ru> reported KERNEL_VERSION: 2.6.31 DESCRIBE: Driver drivers/char/isicom.c might sleep in atomic context, because it calls tty_port_xmit_buf under spin_lock. ./drivers/char/isicom.c: 1307 static void isicom_hangup(struct tty_struct *tty) 1308 { ... 1315 spin_lock_irqsave(&port->card->card_lock, flags); 1316 isicom_shutdown_port(port); ... Path to might_sleep macro from isicom_hangup: 1. isicom_hangup calls spin_lock_irqsave (drivers/char/isicom.c:1315) and then calls isicom_shutdown_port. 2. isiscom_shutdown_port calls tty_port_free_xmit_buf at drivers/char/isicom.c:906 3. tty_port_free_xmit_buf calls mutex_lock at drivers/char/tty_port:48 Found by Linux Driver Verification Project. Reported-by: Alexander Strakh <strakh@ispras.ru> Signed-off-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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