Re: [patch] carl9170: remove unneeded NULL check

On Sun, Dec 02, 2012 at 02:49:20PM +0100, Christian Lamparter wrote:

On Sunday 02 December 2012 11:42:38 Dan Carpenter wrote:

quoted

The "sta" variable is not checked for NULL consistently and it makes the
static checkers complain.  I asked Christian Lamparter about this and
it turns out the check is not needed.  "In fact, in order to set up a
ampdu session, the stack would call the driver's op_ampdu_action
callback which always needs a station."

that would be from the thread:
<http://www.spinics.net/lists/linux-wireless/msg94526.html>
 

quoted

I have removed the check.

I think this will bug for multicast and injected frames.
 
It is not possible for the sta(tion) pointer to be NULL if
the frame has the IEEE80211_TX_CTL_AMPDU flag set. So the
sta == NULL check can be avoided when calling 
carl9170_tx_ampdu_queue. This is because mac80211 tracks
all aggregation sessions within the station struct.
Of course, this is something that the checker tool can't
possibly deduce, but it has a point and we can add a check
like this [see attached draft patch]:

What do you think [or more to the point: what does the
checker say?]

So we wouldn't apply my patch, we would apply that one instead?

I think that's great.  My static checker doesn't understand bit
flags yet so it would complain but it would be obvious to a human
reader.

Could you just resend that patch with a signed-off-by?

regards,
dan carpenter