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>

2 files changed, 8 insertions, 4 deletions

diff --git a/drivers/isdn/hisax/elsa.c b/drivers/isdn/hisax/elsa.c
index 2be1c8a3bb5f..d8ef64da26f1 100644
--- a/drivers/isdn/hisax/elsa.c
+++ b/drivers/isdn/hisax/elsa.c
@@ -509,7 +509,8 @@ static void
 set_arcofi(struct IsdnCardState *cs, int bc) {
         cs->dc.isac.arcofi_bc = bc;
         arcofi_fsm(cs, ARCOFI_START, &ARCOFI_COP_5);
-        interruptible_sleep_on(&cs->dc.isac.arcofi_wait);
+        wait_event_interruptible(cs->dc.isac.arcofi_wait,
+                                 cs->dc.isac.arcofi_state == ARCOFI_NOP);
 }
 
 static int
@@ -528,7 +529,8 @@ check_arcofi(struct IsdnCardState *cs)
                 }
         cs->dc.isac.arcofi_bc = 0;
         arcofi_fsm(cs, ARCOFI_START, &ARCOFI_VERSION);
-        interruptible_sleep_on(&cs->dc.isac.arcofi_wait);
+        wait_event_interruptible(cs->dc.isac.arcofi_wait,
+                                 cs->dc.isac.arcofi_state == ARCOFI_NOP);
         if (!test_and_clear_bit(FLG_ARCOFI_ERROR, &cs->HW_Flags)) {
                 debugl1(cs, "Arcofi response received %d bytes", cs->dc.isac.mon_rxp);
                 p = cs->dc.isac.mon_rx;
@@ -595,7 +597,8 @@ check_arcofi(struct IsdnCardState *cs)
                                Elsa_Types[cs->subtyp],
                                cs->hw.elsa.base + 8);
                 arcofi_fsm(cs, ARCOFI_START, &ARCOFI_XOP_0);
-                interruptible_sleep_on(&cs->dc.isac.arcofi_wait);
+                wait_event_interruptible(cs->dc.isac.arcofi_wait,
+                                 cs->dc.isac.arcofi_state == ARCOFI_NOP);
                 return (1);
         }
         return (0);
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);