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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>
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1 parent eee543e commit 71b578452ec6b2e8a470e3dae89055cd1068a9f0 @JuliaLawall JuliaLawall committed with Jean Delvare Oct 5, 2012
Showing with 4 additions and 7 deletions.
  1. +4 −7 drivers/i2c/i2c-smbus.c
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11 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;
}

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