Input: HIL - fix rwlock recursion bug

The following bug happens when insmoding hp_sdc_mlc.ko:

    HP SDC MLC: Registering the System Domain Controller's HIL MLC.
    BUG: rwlock recursion on CPU#0, hotplug/1814, 00854734
    Backtrace:
     [<10267560>] _raw_write_lock+0x50/0x88
     [<10104008>] _write_lock_irqsave+0x14/0x24
     [<008537d4>] hp_sdc_mlc_out+0x38/0x25c [hp_sdc_mlc]
     [<0084ebd8>] hilse_donode+0x308/0x470 [hil_mlc]
     [<0084ed80>] hil_mlcs_process+0x40/0x6c [hil_mlc]
     [<10130f80>] tasklet_action+0x78/0xb8
     [<10130cec>] __do_softirq+0x60/0xcc
     [<1010428c>] __lock_text_end+0x38/0x48
     [<10108348>] do_cpu_irq_mask+0xf0/0x11c
     [<1010b068>] intr_return+0x0/0xc

Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

1 files changed, 2 insertions, 17 deletions

diff --git a/drivers/input/serio/hp_sdc_mlc.c b/drivers/input/serio/hp_sdc_mlc.c
index cb0b28877e05..c45ea74d53e4 100644
--- a/drivers/input/serio/hp_sdc_mlc.c
+++ b/drivers/input/serio/hp_sdc_mlc.c
@@ -142,14 +142,11 @@ static void hp_sdc_mlc_isr (int irq, void *dev_id,
 
 static int hp_sdc_mlc_in(hil_mlc *mlc, suseconds_t timeout)
 {
-	unsigned long flags;
 	struct hp_sdc_mlc_priv_s *priv;
 	int rc = 2;
 
 	priv = mlc->priv;
 
-	write_lock_irqsave(&mlc->lock, flags);
-
 	/* Try to down the semaphore */
 	if (down_trylock(&mlc->isem)) {
 		struct timeval tv;
@@ -178,21 +175,16 @@ static int hp_sdc_mlc_in(hil_mlc *mlc, suseconds_t timeout)
  wasup:
 	up(&mlc->isem);
 	rc = 0;
-	goto done;
  done:
-	write_unlock_irqrestore(&mlc->lock, flags);
 	return rc;
 }
 
 static int hp_sdc_mlc_cts(hil_mlc *mlc)
 {
 	struct hp_sdc_mlc_priv_s *priv;
-	unsigned long flags;
 
 	priv = mlc->priv;
 
-	write_lock_irqsave(&mlc->lock, flags);
-
 	/* Try to down the semaphores -- they should be up. */
 	BUG_ON(down_trylock(&mlc->isem));
 	BUG_ON(down_trylock(&mlc->osem));
@@ -221,26 +213,21 @@ static int hp_sdc_mlc_cts(hil_mlc *mlc)
 	priv->tseq[2] = 1;
 	priv->tseq[3] = 0;
 	priv->tseq[4] = 0;
-	hp_sdc_enqueue_transaction(&priv->trans);
+	__hp_sdc_enqueue_transaction(&priv->trans);
  busy:
-	write_unlock_irqrestore(&mlc->lock, flags);
 	return 1;
  done:
 	priv->trans.act.semaphore = &mlc->osem;
 	up(&mlc->csem);
-	write_unlock_irqrestore(&mlc->lock, flags);
 	return 0;
 }
 
 static void hp_sdc_mlc_out(hil_mlc *mlc)
 {
 	struct hp_sdc_mlc_priv_s *priv;
-	unsigned long flags;
 
 	priv = mlc->priv;
 
-	write_lock_irqsave(&mlc->lock, flags);
-
 	/* Try to down the semaphore -- it should be up. */
 	BUG_ON(down_trylock(&mlc->osem));
 
@@ -250,7 +237,7 @@ static void hp_sdc_mlc_out(hil_mlc *mlc)
  do_data:
 	if (priv->emtestmode) {
 		up(&mlc->osem);
-		goto done;
+		return;
 	}
 	/* Shouldn't be sending commands when loop may be busy */
 	BUG_ON(down_trylock(&mlc->csem));
@@ -313,8 +300,6 @@ static void hp_sdc_mlc_out(hil_mlc *mlc)
 	}
  enqueue:
 	hp_sdc_enqueue_transaction(&priv->trans);
- done:
-	write_unlock_irqrestore(&mlc->lock, flags);
 }
 
 static int __init hp_sdc_mlc_init(void)