i2c-smbus: Convert kzalloc to devm_kzalloc

Converting kzalloc to devm_kzalloc simplifies the code and ensures that the
result, alert, is freed after the irq allocated by the subsequent
devm_request_irq.  This in turn ensures that when an interrupt can be
triggered, the alert structure is still available.

The problem of a free after a devm_request_irq was found using the
following semantic match (http://coccinelle.lip6.fr/)

// <smpl>
@r exists@
expression e1,e2,x,a,b,c,d;
identifier free;
position p1,p2;
@@

  devm_request_irq@p1(e1,e2,...,x)
  ... when any
      when != e2 = a
      when != x = b
  if (...) {
    ... when != e2 = c
        when != x = d
    free@p2(...,x,...);
    ...
    return ...;
  }
// </smpl>

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

1 files changed, 4 insertions, 7 deletions

diff --git a/drivers/i2c/i2c-smbus.c b/drivers/i2c/i2c-smbus.c
index df3e0bf31eb3..92cdd2323b03 100644
--- a/drivers/i2c/i2c-smbus.c
+++ b/drivers/i2c/i2c-smbus.c
@@ -142,7 +142,8 @@ static int smbalert_probe(struct i2c_client *ara,
         struct i2c_adapter *adapter = ara->adapter;
         int res;
 
-        alert = kzalloc(sizeof(struct i2c_smbus_alert), GFP_KERNEL);
+        alert = devm_kzalloc(&ara->dev, sizeof(struct i2c_smbus_alert),
+                             GFP_KERNEL);
         if (!alert)
                 return -ENOMEM;
 
@@ -154,10 +155,8 @@ static int smbalert_probe(struct i2c_client *ara,
         if (setup->irq > 0) {
                 res = devm_request_irq(&ara->dev, setup->irq, smbalert_irq,
                                        0, "smbus_alert", alert);
-                if (res) {
-                        kfree(alert);
+                if (res)
                         return res;
-                }
         }
 
         i2c_set_clientdata(ara, alert);
@@ -167,14 +166,12 @@ static int smbalert_probe(struct i2c_client *ara,
         return 0;
 }
 
-/* IRQ resource is managed so it is freed automatically */
+/* IRQ and memory resources are managed so they are freed automatically */
 static int smbalert_remove(struct i2c_client *ara)
 {
         struct i2c_smbus_alert *alert = i2c_get_clientdata(ara);
 
         cancel_work_sync(&alert->alert);
-
-        kfree(alert);
         return 0;
 }