Re: [PATCH v2] cnic: Replace rcu_dereference() with rcu_access_pointer()

From: Michael Chan
Date: Mon Aug 18 2014 - 19:13:52 EST


On Sun, 2014-08-17 at 13:12 +0300, Andreea-Cristina Bernat wrote:
> The "rcu_dereference()" calls are used directly in conditions.
> Since their return values are never dereferenced it is recommended to use
> "rcu_access_pointer()" instead of "rcu_dereference()".
> Therefore, this patch makes the replacements.
>
> The following Coccinelle semantic patch was used:
> @@
> @@
>
> (
> if(
> (<+...
> - rcu_dereference
> + rcu_access_pointer
> (...)
> ...+>)) {...}
> |
> while(
> (<+...
> - rcu_dereference
> + rcu_access_pointer
> (...)
> ...+>)) {...}
> )
>
> Signed-off-by: Andreea-Cristina Bernat <bernat.ada@xxxxxxxxx>

Acked-by: Michael Chan <mchan@xxxxxxxxxxxx>

> ---
> v2: Modified subject line from
> "rcu: Replace rcu_dereference() with rcu_access_pointer()"
> to
> "cnic: Replace rcu_dereference() with rcu_access_pointer()",
> noted by David Miller <davem@xxxxxxxxxxxxx>
>
> drivers/net/ethernet/broadcom/cnic.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/ethernet/broadcom/cnic.c b/drivers/net/ethernet/broadcom/cnic.c
> index 8244e2b..dad9cb7 100644
> --- a/drivers/net/ethernet/broadcom/cnic.c
> +++ b/drivers/net/ethernet/broadcom/cnic.c
> @@ -381,7 +381,7 @@ static int cnic_iscsi_nl_msg_recv(struct cnic_dev *dev, u32 msg_type,
> break;
>
> rcu_read_lock();
> - if (!rcu_dereference(cp->ulp_ops[CNIC_ULP_L4])) {
> + if (!rcu_access_pointer(cp->ulp_ops[CNIC_ULP_L4])) {
> rc = -ENODEV;
> rcu_read_unlock();
> break;
> @@ -525,7 +525,7 @@ int cnic_unregister_driver(int ulp_type)
> list_for_each_entry(dev, &cnic_dev_list, list) {
> struct cnic_local *cp = dev->cnic_priv;
>
> - if (rcu_dereference(cp->ulp_ops[ulp_type])) {
> + if (rcu_access_pointer(cp->ulp_ops[ulp_type])) {
> pr_err("%s: Type %d still has devices registered\n",
> __func__, ulp_type);
> read_unlock(&cnic_dev_lock);
> @@ -573,7 +573,7 @@ static int cnic_register_device(struct cnic_dev *dev, int ulp_type,
> mutex_unlock(&cnic_lock);
> return -EAGAIN;
> }
> - if (rcu_dereference(cp->ulp_ops[ulp_type])) {
> + if (rcu_access_pointer(cp->ulp_ops[ulp_type])) {
> pr_err("%s: Type %d has already been registered to this device\n",
> __func__, ulp_type);
> mutex_unlock(&cnic_lock);


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