On Thu, Feb 26, 2009 at 05:03:39PM +0000, Sitsofe Wheeler wrote:
>
> Note that I was able to reproduce it again : )
By the way, here's the theoretical race I was alluding to. ath5k_reset
happens pretty frequently when scanning, and it's possible that the rx
tasklet is run on another cpu after interrupts are turned off, but
it's a small window and I couldn't trigger it with any mdelays.
[PATCH] ath5k: manipulate rxlink and descriptor address under rxbuf lock
Grabbing an ath5k_buf then dropping the lock is racy because the
referenced descriptor can be obtained in another thread and released
before the buffer is handed to the hardware. Likewise, manipulating
sc->rxlink without the lock can lead to having multiple self-linked
hardware descriptors.
Signed-off-by: Bob Copeland <me@xxxxxxxxxxxxxxx>
---
drivers/net/wireless/ath5k/base.c | 5 ++---
1 files changed, 2 insertions(+), 3 deletions(-)
diff --git a/drivers/net/wireless/ath5k/base.c b/drivers/net/wireless/ath5k/base.c
index 8d4b11c..0d3adb5 100644
--- a/drivers/net/wireless/ath5k/base.c
+++ b/drivers/net/wireless/ath5k/base.c
@@ -1586,9 +1586,8 @@ ath5k_rx_start(struct ath5k_softc *sc)
ATH5K_DBG(sc, ATH5K_DEBUG_RESET, "cachelsz %u rxbufsize %u\n",
sc->cachelsz, sc->rxbufsize);
- sc->rxlink = NULL;
-
spin_lock_bh(&sc->rxbuflock);
+ sc->rxlink = NULL;
list_for_each_entry(bf, &sc->rxbuf, list) {
ret = ath5k_rxbuf_setup(sc, bf);
if (ret != 0) {
@@ -1597,9 +1596,9 @@ ath5k_rx_start(struct ath5k_softc *sc)
}
}
bf = list_first_entry(&sc->rxbuf, struct ath5k_buf, list);
+ ath5k_hw_set_rxdp(ah, bf->daddr);
spin_unlock_bh(&sc->rxbuflock);
- ath5k_hw_set_rxdp(ah, bf->daddr);
ath5k_hw_start_rx_dma(ah); /* enable recv descriptors */
ath5k_mode_setup(sc); /* set filters, etc. */
ath5k_hw_start_rx_pcu(ah); /* re-enable PCU/DMA engine */
--
1.6.0.6
--
Bob Copeland %% www.bobcopeland.com
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