isdn: hisax/elsa: fix sleep_on race in elsa FSM

The state machine code in the elsa driver uses interruptible_sleep_on
to wait for state changes, which is racy. A closer look at the possible
states reveals that it is always used to wait for getting back into
ARCOFI_NOP, so we can use wait_event_interruptible instead.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Karsten Keil <isdn@linux-pingi.de>
Cc: netdev@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/isdn/hisax/elsa_ser.c b/drivers/isdn/hisax/elsa_ser.c
index 3f84dd8f1757..a2a358c1dc8e 100644
--- a/drivers/isdn/hisax/elsa_ser.c
+++ b/drivers/isdn/hisax/elsa_ser.c
@@ -573,7 +573,8 @@ modem_l2l1(struct PStack *st, int pr, void *arg)
                 test_and_clear_bit(BC_FLG_ACTIV, &bcs->Flag);
                 bcs->cs->dc.isac.arcofi_bc = st->l1.bc;
                 arcofi_fsm(bcs->cs, ARCOFI_START, &ARCOFI_XOP_0);
-                interruptible_sleep_on(&bcs->cs->dc.isac.arcofi_wait);
+                wait_event_interruptible(bcs->cs->dc.isac.arcofi_wait,
+                                 bcs->cs->dc.isac.arcofi_state == ARCOFI_NOP);
                 bcs->cs->hw.elsa.MFlag = 1;
         } else {
                 printk(KERN_WARNING "ElsaSer: unknown pr %x\n", pr);