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openvswitch: simplify sample action implementation

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The current sample() function implementation is more complicated
than necessary in handling single user space action optimization
and skb reference counting. There is no functional changes.

Signed-off-by: Andy Zhou <azhou@nicira.com>
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
This commit is contained in:
Andy Zhou 2014-09-15 19:33:50 -07:00 committed by Pravin B Shelar
parent 8c8b1b83fc
commit 32ae87ff79
1 changed files with 18 additions and 24 deletions
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42
net/openvswitch/actions.c
View file

@ -448,7 +448,6 @@ static int sample(struct datapath *dp, struct sk_buff *skb,
{
const struct nlattr *acts_list = NULL;
const struct nlattr *a;
struct sk_buff *sample_skb;
int rem;
for (a = nla_data(attr), rem = nla_len(attr); rem > 0;
@ -468,31 +467,26 @@ static int sample(struct datapath *dp, struct sk_buff *skb,
rem = nla_len(acts_list);
a = nla_data(acts_list);
/* Actions list is either empty or only contains a single user-space
* action, the latter being a special case as it is the only known
* usage of the sample action.
* In these special cases don't clone the skb as there are no
* side-effects in the nested actions.
* Otherwise, clone in case the nested actions have side effects.
*/
if (likely(rem == 0 || (nla_type(a) == OVS_ACTION_ATTR_USERSPACE &&
last_action(a, rem)))) {
sample_skb = skb;
skb_get(skb);
} else {
sample_skb = skb_clone(skb, GFP_ATOMIC);
if (!sample_skb) /* Skip sample action when out of memory. */
return 0;
}
/* Actions list is empty, do nothing */
if (unlikely(!rem))
return 0;
/* Note that do_execute_actions() never consumes skb.
* In the case where skb has been cloned above it is the clone that
* is consumed. Otherwise the skb_get(skb) call prevents
* consumption by do_execute_actions(). Thus, it is safe to simply
* return the error code and let the caller (also
* do_execute_actions()) free skb on error.
/* The only known usage of sample action is having a single user-space
* action. Treat this usage as a special case.
* The output_userspace() should clone the skb to be sent to the
* user space. This skb will be consumed by its caller.
*/
return do_execute_actions(dp, sample_skb, key, a, rem);
if (likely(nla_type(a) == OVS_ACTION_ATTR_USERSPACE &&
last_action(a, rem)))
return output_userspace(dp, skb, key, a);
skb = skb_clone(skb, GFP_ATOMIC);
if (!skb)
/* Skip the sample action when out of memory. */
return 0;
/* do_execute_actions() will consume the cloned skb. */
return do_execute_actions(dp, skb, key, a, rem);
}
static int execute_set_action(struct sk_buff *skb,