We have seen several DMA races when we race against stopping and starting the PCU. I suspect that when we cannot stop the PCU we may hit some of these same races so warn against them for now but only when debugging (CONFIG_ATH_DEBUG) is enabled. If you run into this warning and are a developer, please fix the cause of the warning. The potential here, although I cannot prove yet, is that the DMA engine can be confused and start writing to a buffer that was already DMA'd before and at least the kernel assumes is not being accessed by hardware anymore. Cc: Ben Greear <greearb@xxxxxxxxxxxxxxx> Cc: Kyungwan Nam <kyungwan.nam@xxxxxxxxxxx> Signed-off-by: Luis R. Rodriguez <lrodriguez@xxxxxxxxxxx> --- drivers/net/wireless/ath/ath9k/recv.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-) diff --git a/drivers/net/wireless/ath/ath9k/recv.c b/drivers/net/wireless/ath/ath9k/recv.c index c04a940..87fabf8 100644 --- a/drivers/net/wireless/ath/ath9k/recv.c +++ b/drivers/net/wireless/ath/ath9k/recv.c @@ -528,6 +528,8 @@ bool ath_stoprecv(struct ath_softc *sc) sc->rx.rxlink = NULL; spin_unlock_bh(&sc->rx.rxbuflock); + ATH_DBG_WARN(!stopped, "Could not stop RX, we could be " + "confusing the DMA engine when we start RX up\n"); return stopped; } -- 1.7.0.4 -- 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
