Commit 2493c0c1 authored by Alan Cox's avatar Alan Cox Committed by Greg Kroah-Hartman
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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: default avatarAlexander Strakh <strakh@ispras.ru>
Signed-off-by: default avatarAlan Cox <alan@linux.intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 07f86c03
...@@ -887,7 +887,6 @@ static void isicom_shutdown_port(struct isi_port *port) ...@@ -887,7 +887,6 @@ static void isicom_shutdown_port(struct isi_port *port)
{ {
struct isi_board *card = port->card; struct isi_board *card = port->card;
tty_port_free_xmit_buf(&port->port);
if (--card->count < 0) { if (--card->count < 0) {
pr_dbg("isicom_shutdown_port: bad board(0x%lx) count %d.\n", pr_dbg("isicom_shutdown_port: bad board(0x%lx) count %d.\n",
card->base, card->count); card->base, card->count);
...@@ -927,6 +926,7 @@ static void isicom_shutdown(struct tty_port *port) ...@@ -927,6 +926,7 @@ static void isicom_shutdown(struct tty_port *port)
outw(card->port_status, card->base + 0x02); outw(card->port_status, card->base + 0x02);
isicom_shutdown_port(ip); isicom_shutdown_port(ip);
spin_unlock_irqrestore(&card->card_lock, flags); spin_unlock_irqrestore(&card->card_lock, flags);
tty_port_free_xmit_buf(port);
} }
static void isicom_close(struct tty_struct *tty, struct file *filp) static void isicom_close(struct tty_struct *tty, struct file *filp)
......
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