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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@ -887,7 +887,6 @@ static void isicom_shutdown_port(struct isi_port *port)
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{
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struct isi_board *card = port->card;
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tty_port_free_xmit_buf(&port->port);
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if (--card->count < 0) {
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pr_dbg("isicom_shutdown_port: bad board(0x%lx) count %d.\n",
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card->base, card->count);
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@ -927,6 +926,7 @@ static void isicom_shutdown(struct tty_port *port)
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outw(card->port_status, card->base + 0x02);
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isicom_shutdown_port(ip);
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spin_unlock_irqrestore(&card->card_lock, flags);
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tty_port_free_xmit_buf(port);
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}
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static void isicom_close(struct tty_struct *tty, struct file *filp)
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