On Tue, Oct 11, 2011 at 02:26:30PM +0200, Grumbach, Emmanuel wrote: > > > > On Mon, Oct 10, 2011 at 07:27:02AM -0700, Wey-Yi Guy wrote: > > > While inspecting the code, I saw that iwl_tx_queue_unmap modifies > > > the read pointer of the Tx queue without taking any locks. This means > > > that it can race with the reclaim flow. This can possibly lead to > > > a DMA warning complaining that we unmap the same buffer twice. > > > > > > This is more a W/A than a fix since it is really weird to take > > > sta_lock inside iwl_tx_queue_unmap, but it can help until we revamp > > > the locking model in the transport layer. > > > > > > Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@xxxxxxxxx> > > > Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@xxxxxxxxx> > > > --- > > > drivers/net/wireless/iwlwifi/iwl-trans-pcie.c | 3 +++ > > > 1 files changed, 3 insertions(+), 0 deletions(-) > > > > > > diff --git a/drivers/net/wireless/iwlwifi/iwl-trans-pcie.c > > b/drivers/net/wireless/iwlwifi/iwl-trans-pcie.c > > > index 60067c7..f69aecb 100644 > > > --- a/drivers/net/wireless/iwlwifi/iwl-trans-pcie.c > > > +++ b/drivers/net/wireless/iwlwifi/iwl-trans-pcie.c > > > @@ -406,6 +406,7 @@ static void iwl_tx_queue_unmap(struct iwl_trans > > *trans, int txq_id) > > > struct iwl_tx_queue *txq = &trans_pcie->txq[txq_id]; > > > struct iwl_queue *q = &txq->q; > > > enum dma_data_direction dma_dir; > > > + unsigned long flags; > > > > > > if (!q->n_bd) > > > return; > > > @@ -418,12 +419,14 @@ static void iwl_tx_queue_unmap(struct iwl_trans > > *trans, int txq_id) > > > else > > > dma_dir = DMA_TO_DEVICE; > > > > > > + spin_lock_irqsave(&trans->shrd->sta_lock, flags); > > sta_lock does not look like right lock to use. > > > True. And I wrote in the commit message that this is a W/A until we revamp the locking model. Why not simply take hcmd_lock? -- 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
