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Subject[PATCH 35/93] ath9k: add a better fix for the rx tasklet vs rx flush race
Date
3.5.7.5 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Felix Fietkau <nbd@openwrt.org>

commit 7fc00a3054b70b1794c2d64db703eb467ad0365c upstream.

Ensure that the rx tasklet is no longer running when entering the reset path.
Also remove the distinction between flush and no-flush frame processing.
If a frame has been received and ACKed by the hardware, the stack needs to see
it, so that the BA receive window does not go out of sync.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
[ herton: SC_OP_RXFLUSH defined as a macro, and *_bit operations were not
being used yet ]
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>
---
drivers/net/wireless/ath/ath9k/ath9k.h | 1 -
drivers/net/wireless/ath/ath9k/debug.c | 1 -
drivers/net/wireless/ath/ath9k/debug.h | 2 --
drivers/net/wireless/ath/ath9k/main.c | 4 ++++
drivers/net/wireless/ath/ath9k/recv.c | 15 ---------------
5 files changed, 4 insertions(+), 19 deletions(-)

diff --git a/drivers/net/wireless/ath/ath9k/ath9k.h b/drivers/net/wireless/ath/ath9k/ath9k.h
index 4866550..cd23a03 100644
--- a/drivers/net/wireless/ath/ath9k/ath9k.h
+++ b/drivers/net/wireless/ath/ath9k/ath9k.h
@@ -588,7 +588,6 @@ struct ath_ant_comb {
#define SC_OP_INVALID BIT(0)
#define SC_OP_BEACONS BIT(1)
#define SC_OP_OFFCHANNEL BIT(2)
-#define SC_OP_RXFLUSH BIT(3)
#define SC_OP_TSF_RESET BIT(4)
#define SC_OP_BT_PRIORITY_DETECTED BIT(5)
#define SC_OP_BT_SCAN BIT(6)
diff --git a/drivers/net/wireless/ath/ath9k/debug.c b/drivers/net/wireless/ath/ath9k/debug.c
index fde700c..9c6169e 100644
--- a/drivers/net/wireless/ath/ath9k/debug.c
+++ b/drivers/net/wireless/ath/ath9k/debug.c
@@ -919,7 +919,6 @@ static ssize_t read_file_recv(struct file *file, char __user *user_buf,
RXS_ERR("RX-LENGTH-ERR", rx_len_err);
RXS_ERR("RX-OOM-ERR", rx_oom_err);
RXS_ERR("RX-RATE-ERR", rx_rate_err);
- RXS_ERR("RX-DROP-RXFLUSH", rx_drop_rxflush);
RXS_ERR("RX-TOO-MANY-FRAGS", rx_too_many_frags_err);

PHY_ERR("UNDERRUN ERR", ATH9K_PHYERR_UNDERRUN);
diff --git a/drivers/net/wireless/ath/ath9k/debug.h b/drivers/net/wireless/ath/ath9k/debug.h
index c34da09..3883bbe 100644
--- a/drivers/net/wireless/ath/ath9k/debug.h
+++ b/drivers/net/wireless/ath/ath9k/debug.h
@@ -184,7 +184,6 @@ struct ath_tx_stats {
* @rx_oom_err: No. of frames dropped due to OOM issues.
* @rx_rate_err: No. of frames dropped due to rate errors.
* @rx_too_many_frags_err: Frames dropped due to too-many-frags received.
- * @rx_drop_rxflush: No. of frames dropped due to RX-FLUSH.
* @rx_beacons: No. of beacons received.
* @rx_frags: No. of rx-fragements received.
*/
@@ -203,7 +202,6 @@ struct ath_rx_stats {
u32 rx_oom_err;
u32 rx_rate_err;
u32 rx_too_many_frags_err;
- u32 rx_drop_rxflush;
u32 rx_beacons;
u32 rx_frags;
};
diff --git a/drivers/net/wireless/ath/ath9k/main.c b/drivers/net/wireless/ath/ath9k/main.c
index b5fa9eb..ecd306f 100644
--- a/drivers/net/wireless/ath/ath9k/main.c
+++ b/drivers/net/wireless/ath/ath9k/main.c
@@ -250,6 +250,8 @@ static bool ath_prepare_reset(struct ath_softc *sc, bool retry_tx, bool flush)
ath9k_debug_samp_bb_mac(sc);
ath9k_hw_disable_interrupts(ah);

+ tasklet_disable(&sc->intr_tq);
+
if (!ath_stoprecv(sc))
ret = false;

@@ -264,6 +266,8 @@ static bool ath_prepare_reset(struct ath_softc *sc, bool retry_tx, bool flush)
ath_flushrecv(sc);
}

+ tasklet_enable(&sc->intr_tq);
+
return ret;
}

diff --git a/drivers/net/wireless/ath/ath9k/recv.c b/drivers/net/wireless/ath/ath9k/recv.c
index 14b4d07..4d31389 100644
--- a/drivers/net/wireless/ath/ath9k/recv.c
+++ b/drivers/net/wireless/ath/ath9k/recv.c
@@ -322,7 +322,6 @@ int ath_rx_init(struct ath_softc *sc, int nbufs)
int error = 0;

spin_lock_init(&sc->sc_pcu_lock);
- sc->sc_flags &= ~SC_OP_RXFLUSH;
spin_lock_init(&sc->rx.rxbuflock);

common->rx_bufsize = IEEE80211_MAX_MPDU_LEN / 2 +
@@ -535,11 +534,9 @@ bool ath_stoprecv(struct ath_softc *sc)

void ath_flushrecv(struct ath_softc *sc)
{
- sc->sc_flags |= SC_OP_RXFLUSH;
if (sc->sc_ah->caps.hw_caps & ATH9K_HW_CAP_EDMA)
ath_rx_tasklet(sc, 1, true);
ath_rx_tasklet(sc, 1, false);
- sc->sc_flags &= ~SC_OP_RXFLUSH;
}

static bool ath_beacon_dtim_pending_cab(struct sk_buff *skb)
@@ -1804,9 +1801,6 @@ int ath_rx_tasklet(struct ath_softc *sc, int flush, bool hp)

do {
bool decrypt_error = false;
- /* If handling rx interrupt and flush is in progress => exit */
- if ((sc->sc_flags & SC_OP_RXFLUSH) && (flush == 0))
- break;

memset(&rs, 0, sizeof(rs));
if (edma)
@@ -1845,15 +1839,6 @@ int ath_rx_tasklet(struct ath_softc *sc, int flush, bool hp)

ath_debug_stat_rx(sc, &rs);

- /*
- * If we're asked to flush receive queue, directly
- * chain it back at the queue without processing it.
- */
- if (sc->sc_flags & SC_OP_RXFLUSH) {
- RX_STAT_INC(rx_drop_rxflush);
- goto requeue_drop_frag;
- }
-
memset(rxs, 0, sizeof(struct ieee80211_rx_status));

rxs->mactime = (tsf & ~0xffffffffULL) | rs.rs_tstamp;
--
1.7.9.5


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