On Mon, 2011-05-30 at 09:55 +0200, Helmut Schaa wrote:

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AFAICT not all tx calls from mac80211 are protected by local_bh_disable/enable. I believe
that this is the case for the "process" context tx calls from

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ieee80211_subif_start_xmit

This should only be called from the network softirq and thus doesn't require bottom halves
to be disabled (AFAIK).

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and
ieee80211_monitor_start_xmit.

Same here.

Hmm, are you sure about this?

Maybe Johannes can clarify this for us ;)

The above assertion ("not all TX calls are protected") is wrong.

Johannes, are all calls to the drivers tx callback done in softirq context or
adequately protected by local_bh_disable/enable? Or is this presumption wrong?

All of them are invoked with BHs disabled.

Cf. ieee80211_tx_skb(), which is the only function that can be called
from process context. The _start_xmit functions listed above are called
by the networking layer and always invoked with BHs disabled.

johannes