On 2011-03-09 2:07 AM, Ben Greear wrote: > On 03/08/2011 04:48 PM, Felix Fietkau wrote: >> The hardware rx filter flag triggered by FIF_PROMISC_IN_BSS is overly broad >> and covers even frames with PHY errors. When this flag is enabled, this message >> shows up frequently during scanning or hardware resets: >> >> ath: Could not stop RX, we could be confusing the DMA engine when we start RX up >> >> Since promiscuous mode is usually not particularly useful, yet enabled by >> default by bridging (either used normally in 4-addr mode, or with hacks >> for various virtualization software), we should sacrifice it for better >> reliability during normal operation. >> >> This patch leaves it enabled if there are active monitor mode interfaces, since >> it's very useful for debugging. >> >> Signed-off-by: Felix Fietkau<nbd@xxxxxxxxxxx> >> Cc: stable@xxxxxxxxxx >> --- >> drivers/net/wireless/ath/ath9k/recv.c | 4 +--- >> 1 files changed, 1 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/net/wireless/ath/ath9k/recv.c b/drivers/net/wireless/ath/ath9k/recv.c >> index cb559e3..a9c3f46 100644 >> --- a/drivers/net/wireless/ath/ath9k/recv.c >> +++ b/drivers/net/wireless/ath/ath9k/recv.c >> @@ -413,9 +413,7 @@ u32 ath_calcrxfilter(struct ath_softc *sc) >> * mode interface or when in monitor mode. AP mode does not need this >> * since it receives all in-BSS frames anyway. >> */ >> - if (((sc->sc_ah->opmode != NL80211_IFTYPE_AP)&& >> - (sc->rx.rxfilter& FIF_PROMISC_IN_BSS)) || >> - (sc->sc_ah->is_monitoring)) >> + if (sc->sc_ah->is_monitoring) >> rfilt |= ATH9K_RX_FILTER_PROM; >> >> if (sc->rx.rxfilter& FIF_CONTROL) > > Should we enable this flag if we have multiple STA > interfaces? I had to add something to ath5k recently > to put it into promisc to properly handle multiple STAs > associated with different APs, for instance. No, multiple interfaces is handled by the BSSID mask. > Do you have any idea *why* enabling this flag causes the DMA error > messages? I don't know why exactly it happens, but it probably cannot be explained without going to the details of the inner workings of the MAC/baseband interaction. But as I mentioned in the description, this flag is overly broad and doesn't just bypass the address match, but lets all kinds of other crap through as well - in many situations where even 'normal' promiscuous behavior would be completely useless. I think because of that, disabling it for non-monitor operation is the right thing to do. - Felix -- 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
