On Sun, Aug 28, 2011 at 10:07 PM, Thomas Pedersen <thomas@xxxxxxxxxxx> wrote: > On Fri, Aug 26, 2011 at 7:22 AM, John W. Linville > <linville@xxxxxxxxxxxxx> wrote: >> On Wed, Aug 24, 2011 at 06:34:24PM -0700, Thomas Pedersen wrote: >>> From: Javier Cardona <javier@xxxxxxxxxxx> >>> >>> This driver reports transmission status to the upper layer >>> (ath5k_tx_frame_completed()) while holding the lock on the transmission >>> queue (txq->lock). Under failure conditions, the mesh stack will >>> attempt to send PERR messages to the previous sender of the failed >>> frame. When that happens the driver will attempt to re-acquire the >>> txq->lock lock causing a deadlock. There are two possible fixes for >>> this, (1) we could defer the transmission of the PERR frame until the >>> lock is released or (2) release the lock before invoking >>> ieee80211_tx_status(). The ath9k driver implements the second approach >>> (see ath_tx_complete() in ath9k/xmit.c) as well as the rt2x00 and b43 >>> drivers. The iwl driver, on the other hand, avoids this problem by >>> invoking ieee80211_tx_status_irqsafe() which effectively defers >>> processing of transmission feedback status. This last approach is the >>> least intrusive is implemented here. >>> >>> Reported by Pedro Larbig (ASPj) >>> --- >>> drivers/net/wireless/ath/ath5k/base.c | 2 +- >>> 1 files changed, 1 insertions(+), 1 deletions(-) >> >> Missing Signed-off-by... >> > Yikes. Also, it looks like ieee80211_tx_status() should not be called > from irq context. Will resubmit a v2 with signoff and comment shortly. I don't get the last statement -- ieee80211_tx_status() -> irqsafe was the very change the patch added. It's running in a bottom half though, not a hard irq. -- Bob Copeland %% www.bobcopeland.com -- 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
