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>

4 files changed, 19 insertions, 25 deletions

diff --git a/drivers/input/serio/hil_mlc.c b/drivers/input/serio/hil_mlc.c
index 485b0742842b..93a1a6ba216a 100644
--- a/drivers/input/serio/hil_mlc.c
+++ b/drivers/input/serio/hil_mlc.c
@@ -716,7 +716,9 @@ static int hilse_donode(hil_mlc *mlc)
                 break;
 
         case HILSE_CTS:
+                write_lock_irqsave(&mlc->lock, flags);
                 nextidx = mlc->cts(mlc) ? node->bad : node->good;
+                write_unlock_irqrestore(&mlc->lock, flags);
                 break;
 
         default:
diff --git a/drivers/input/serio/hp_sdc.c b/drivers/input/serio/hp_sdc.c
index 31826e601fba..6af199805ffc 100644
--- a/drivers/input/serio/hp_sdc.c
+++ b/drivers/input/serio/hp_sdc.c
@@ -100,6 +100,7 @@ EXPORT_SYMBOL(hp_sdc_release_timer_irq);
 EXPORT_SYMBOL(hp_sdc_release_hil_irq);
 EXPORT_SYMBOL(hp_sdc_release_cooked_irq);
 
+EXPORT_SYMBOL(__hp_sdc_enqueue_transaction);
 EXPORT_SYMBOL(hp_sdc_enqueue_transaction);
 EXPORT_SYMBOL(hp_sdc_dequeue_transaction);
 
@@ -593,18 +594,15 @@ unsigned long hp_sdc_put(void)
 }
 
 /******* Functions called in either user or kernel context ****/
-int hp_sdc_enqueue_transaction(hp_sdc_transaction *this)
+int __hp_sdc_enqueue_transaction(hp_sdc_transaction *this)
 {
-        unsigned long flags;
         int i;
 
         if (this == NULL) {
-                tasklet_schedule(&hp_sdc.task);
+                BUG();
                 return -EINVAL;
         }
 
-        write_lock_irqsave(&hp_sdc.lock, flags);
-
         /* Can't have same transaction on queue twice */
         for (i = 0; i < HP_SDC_QUEUE_LEN; i++)
                 if (hp_sdc.tq[i] == this)
@@ -617,21 +615,29 @@ int hp_sdc_enqueue_transaction(hp_sdc_transaction *this)
         for (i = 0; i < HP_SDC_QUEUE_LEN; i++)
                 if (hp_sdc.tq[i] == NULL) {
                         hp_sdc.tq[i] = this;
-                        write_unlock_irqrestore(&hp_sdc.lock, flags);
                         tasklet_schedule(&hp_sdc.task);
                         return 0;
                 }
 
-        write_unlock_irqrestore(&hp_sdc.lock, flags);
         printk(KERN_WARNING PREFIX "No free slot to add transaction.\n");
         return -EBUSY;
 
  fail:
-        write_unlock_irqrestore(&hp_sdc.lock,flags);
         printk(KERN_WARNING PREFIX "Transaction add failed: transaction already queued?\n");
         return -EINVAL;
 }
 
+int hp_sdc_enqueue_transaction(hp_sdc_transaction *this) {
+        unsigned long flags;
+        int ret;
+
+        write_lock_irqsave(&hp_sdc.lock, flags);
+        ret = __hp_sdc_enqueue_transaction(this);
+        write_unlock_irqrestore(&hp_sdc.lock,flags);
+
+        return ret;
+}
+
 int hp_sdc_dequeue_transaction(hp_sdc_transaction *this)
 {
         unsigned long flags;
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)
diff --git a/include/linux/hp_sdc.h b/include/linux/hp_sdc.h
index debd71515312..9db3d454887f 100644
--- a/include/linux/hp_sdc.h
+++ b/include/linux/hp_sdc.h
@@ -71,6 +71,7 @@ typedef struct {
           struct semaphore *semaphore;  /* Semaphore to sleep on. */
         } act;
 } hp_sdc_transaction;
+int __hp_sdc_enqueue_transaction(hp_sdc_transaction *this);
 int hp_sdc_enqueue_transaction(hp_sdc_transaction *this);
 int hp_sdc_dequeue_transaction(hp_sdc_transaction *this);