On Mon, Aug 29, 2011 at 7:09 AM, Bob Copeland <me@xxxxxxxxxxxxxxx> wrote: > 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 I meant to say "In addition to the above discussion, ieee80211_tx_status() should not be called from interrupt context anyway". > the very change the patch added. It's running in a bottom half > though, not a hard irq. > Even in a bottom half we're still in "interrupt" context, right? -- 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
