ath9k: remove sc->rx.rxbuflock to fix a deadlock

The commit "ath9k: fix rx flush handling" added a deadlock that happens
because ath_rx_tasklet is called in a section that has already taken the
rx buffer lock.

It seems that the only purpose of the rxbuflock was a band-aid fix to the
reset vs rx tasklet race, which has been properly fixed in the commit
"ath9k: add a better fix for the rx tasklet vs rx flush race".

Now that the fix is in, we can safely remove the lock to avoid such issues.

Cc: stable@vger.kernel.org
Reported-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

2 files changed, 0 insertions, 14 deletions

diff --git a/drivers/net/wireless/ath/ath9k/ath9k.h b/drivers/net/wireless/ath/ath9k/ath9k.h
index 32b2d5cd9a5a..42794c546a40 100644
--- a/drivers/net/wireless/ath/ath9k/ath9k.h
+++ b/drivers/net/wireless/ath/ath9k/ath9k.h
@@ -317,7 +317,6 @@ struct ath_rx {
         u32 *rxlink;
         u32 num_pkts;
         unsigned int rxfilter;
-        spinlock_t rxbuflock;
         struct list_head rxbuf;
         struct ath_descdma rxdma;
         struct ath_buf *rx_bufptr;
diff --git a/drivers/net/wireless/ath/ath9k/recv.c b/drivers/net/wireless/ath/ath9k/recv.c
index 67f58d4bb10e..90752f246970 100644
--- a/drivers/net/wireless/ath/ath9k/recv.c
+++ b/drivers/net/wireless/ath/ath9k/recv.c
@@ -254,8 +254,6 @@ rx_init_fail:
 
 static void ath_edma_start_recv(struct ath_softc *sc)
 {
-        spin_lock_bh(&sc->rx.rxbuflock);
-
         ath9k_hw_rxena(sc->sc_ah);
 
         ath_rx_addbuffer_edma(sc, ATH9K_RX_QUEUE_HP,
@@ -267,8 +265,6 @@ static void ath_edma_start_recv(struct ath_softc *sc)
         ath_opmode_init(sc);
 
         ath9k_hw_startpcureceive(sc->sc_ah, !!(sc->hw->conf.flags & IEEE80211_CONF_OFFCHANNEL));
-
-        spin_unlock_bh(&sc->rx.rxbuflock);
 }
 
 static void ath_edma_stop_recv(struct ath_softc *sc)
@@ -285,7 +281,6 @@ int ath_rx_init(struct ath_softc *sc, int nbufs)
         int error = 0;
 
         spin_lock_init(&sc->sc_pcu_lock);
-        spin_lock_init(&sc->rx.rxbuflock);
 
         common->rx_bufsize = IEEE80211_MAX_MPDU_LEN / 2 +
                              sc->sc_ah->caps.rx_status_len;
@@ -446,7 +441,6 @@ int ath_startrecv(struct ath_softc *sc)
                 return 0;
         }
 
-        spin_lock_bh(&sc->rx.rxbuflock);
         if (list_empty(&sc->rx.rxbuf))
                 goto start_recv;
 
@@ -467,8 +461,6 @@ start_recv:
         ath_opmode_init(sc);
         ath9k_hw_startpcureceive(ah, !!(sc->hw->conf.flags & IEEE80211_CONF_OFFCHANNEL));
 
-        spin_unlock_bh(&sc->rx.rxbuflock);
-
         return 0;
 }
 
@@ -484,7 +476,6 @@ bool ath_stoprecv(struct ath_softc *sc)
         struct ath_hw *ah = sc->sc_ah;
         bool stopped, reset = false;
 
-        spin_lock_bh(&sc->rx.rxbuflock);
         ath9k_hw_abortpcurecv(ah);
         ath9k_hw_setrxfilter(ah, 0);
         stopped = ath9k_hw_stopdmarecv(ah, &reset);
@@ -495,7 +486,6 @@ bool ath_stoprecv(struct ath_softc *sc)
                 ath_edma_stop_recv(sc);
         else
                 sc->rx.rxlink = NULL;
-        spin_unlock_bh(&sc->rx.rxbuflock);
 
         if (!(ah->ah_flags & AH_UNPLUGGED) &&
             unlikely(!stopped)) {
@@ -1059,7 +1049,6 @@ int ath_rx_tasklet(struct ath_softc *sc, int flush, bool hp)
                 dma_type = DMA_FROM_DEVICE;
 
         qtype = hp ? ATH9K_RX_QUEUE_HP : ATH9K_RX_QUEUE_LP;
-        spin_lock_bh(&sc->rx.rxbuflock);
 
         tsf = ath9k_hw_gettsf64(ah);
         tsf_lower = tsf & 0xffffffff;
@@ -1254,8 +1243,6 @@ requeue:
                 }
         } while (1);
 
-        spin_unlock_bh(&sc->rx.rxbuflock);
-
         if (!(ah->imask & ATH9K_INT_RXEOL)) {
                 ah->imask |= (ATH9K_INT_RXEOL | ATH9K_INT_RXORN);
                 ath9k_hw_set_interrupts(ah);