Man page 9 : cfg80211_testmode_alloc_reply_skb

cfg80211_testmode_alloc_reply_skb - allocate testmode reply

struct sk_buff * cfg80211_testmode_alloc_reply_skb(struct wiphy *  wiphy , int  approxlen );

wiphy
    the wiphy

approxlen
    an upper bound of the length of the data that will be put into the skb

This function allocates and pre-fills an skb for a reply to the testmode command. Since it is intended for a reply, calling it outside of the testmode_cmd operation is invalid.

The returned skb is pre-filled with the wiphy index and set up in a way that any data that is put into the skb (with skb_put, nla_put or similar) will end up being within the NL80211_ATTR_TESTDATA attribute, so all that needs to be done with the skb is adding data for the corresponding userspace tool which can then read that data out of the testdata attribute. You must not modify the skb in any other way.

When done, call cfg80211_testmode_reply with the skb and return its error code as the result of the testmode_cmd operation.

An allocated and pre-filled skb. NULL if any errors happen.

Johannes Berg <>
    Author.