David Miller <[EMAIL PROTECTED]> writes: > From: [EMAIL PROTECTED] (Eric W. Biederman) > Date: Thu, 27 Sep 2007 01:48:00 -0600 > >> I'm not doing get_cpu/put_cpu so does the comment make sense >> in relationship to per_cpu_ptr? > > It is possible. But someone would need to go check for > sure.
Verified. hard_start_xmit is called inside of a rcu_read_lock_bh(),rcu_read_unlock_bh() pair. Which means the code will only run on one cpu. Therefore we do not need get_cpu/put_cpu. In addition per_cpu_ptr is valid. As it is just a lookup into a NR_CPUS sized array by smp_processor_id() to return the address of the specific cpu. The only difference between per_cpu_ptr and __get_cpu_var() are the implementation details between statically allocated and dynamically allocated per cpu state. So the comment is still valid, and still interesting it just should say per_cpu_ptr instead of __get_cpu_var. Signed-off-by: "Eric W. Biederman" <[EMAIL PROTECTED]> --- diff --git a/drivers/net/loopback.c b/drivers/net/loopback.c index 0f9d8c6..756e267 100644 --- a/drivers/net/loopback.c +++ b/drivers/net/loopback.c @@ -154,7 +154,7 @@ static int loopback_xmit(struct sk_buff *skb, struct net_device *dev) #endif dev->last_rx = jiffies; - /* it's OK to use __get_cpu_var() because BHs are off */ + /* it's OK to use per_cpu_ptr() because BHs are off */ pcpu_lstats = netdev_priv(dev); lb_stats = per_cpu_ptr(pcpu_lstats, smp_processor_id()); lb_stats->bytes += skb->len; - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html