On Fri, Feb 22, 2008 at 12:29 PM, Johannes Berg <johannes@xxxxxxxxxxxxxxxx> wrote: > Hi, > > Looking through the locking in sta_info I noticed it was completely > broken especially wrt STA flag updates. However, most other things are > fine iff the drivers only use EITHER ieee80211_rx_irqsafe and > ieee80211_tx_status_irqsafe OR __ieee80211_rx and ieee80211_tx_status. > Also, in the latter case, drivers have to make sure that only one of > each of those calls is active at the same time, even on an SMP system. > > The only drivers that currently use the non-irqsafe versions are ath5k > and iwlwifi, where iwlwifi even mixes between the two groups. ath5k > seems fine, it defers both to tasklets so only one call can be done at a > time. > > With iwlwifi, however, there is a possibility that it invokes > ieee80211_tx_status() on one CPU while mac80211's tasklet is processing > another TX status that was submitted with ieee80211_tx_status_irqsafe(). > Tomas, I think you mentioned that the TX status processing can't > actually ever call the non-irqsafe version, can we remove that call to > be sure? :) Actually alike athk also iwlwifi driver calls tx_status from a tasklet therfore the irqsafe can be removed. I've tested that it worked so far However we added start_tx_ba_cb(_irqsafe) callback to get around AMPDU queues reordering In this case we have to use both handlers so I wonder where we have problem here as the same mechanism as tx_status is used. In general I'm missing some asynchronous mechanism that driver can notify mac80211 about it's state. Except BA states there is for example netif_carrier_off/on functionality in the driver level. It would be very useful for early notification of disconnection. A disconnection can happen due to device resume or internal recoverable error. In this cases I would expect mac to try associate again upon such trigger. Thanks Tomas Thanks > Alternatively, short of imposing these requirements, we can add new > locking in mac80211. I don't think that would be good though. > > johannes > - To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
