作用

函數(shù) devm_kzalloc() 和kzalloc()一樣都是內(nèi)核內(nèi)存分配函數(shù)，但是devm_kzalloc()是跟設(shè)備(device)有關(guān)的,，

當(dāng)設(shè)備(device)被detached或者驅(qū)動(driver)卸載(unloaded)時,，內(nèi)存會被自動釋放。另外,，也可以通過函數(shù)

devm_kfree()手動釋放,。

    而kzalloc()則需要手動釋放(使用kfree())，但如果工程師檢查不仔細(xì),，則有可能造成內(nèi)存泄漏,。

格式

static inline void * devm_kzalloc（struct device * dev,，size_t size，gfp_t gfp）

{

    return devm_kmalloc（dev,，size,，gfp | __GFP_ZERO）;                                                                                                                                                         

}

void * devm_kmalloc(struct device *dev, size_t size, gfp_t gfp)                                                                                                                                               

{

    struct devres *dr;

    dr = alloc_dr(devm_kmalloc_release, size, gfp, dev_to_node(dev));

    if (unlikely(!dr))

        return NULL;

    set_node_dbginfo(&dr->node, "devm_kzalloc_release", size);

    devres_add(dev, dr->data);

    return dr->data;

}

EXPORT_SYMBOL_GPL(devm_kmalloc);

void devm_kfree（struct device * dev，void * p）                                                                                                                                                                  

{

    int rc;

    rc = devres_destroy（dev,，devm_kmalloc_release,，devm_kmalloc_match，p）;

    WARN_ON（RC）;

}

EXPORT_SYMBOL_GPL(devm_kfree);

示例

struct s3c2440_i2c_dev {

  struct device *dev;

  void __iomem *base;

  struct i2c_msg *msg;

  u32  frequency;

  int speed_mode;

  int slave_addr;

  struct i2c_adapter  adap;

};

static int s3c2440_i2c_probe(struct platform_device *pdev)

{

  struct s3c2440_i2c_dev *i2c_dev;

  struct i2c_adapter *adap;

  struct device *dev = &pdev->dev;

  struct resource *res;

  i2c_dev = devm_kzalloc(&pdev->dev, sizeof(struct s3c2440_i2c_dev), GFP_KERNEL);

  if(!i2c_dev)

  return -ENOMEM;

  ...

}