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    SubjectRe: [Bug #12490] ath5k related kernel panic in 2.6.29-rc1
    On Tue, Apr 07, 2009 at 12:03:45PM +0200, Johannes Berg wrote:
    >
    > > Anyway here's a patch to buy some time. Johannes, would this be
    > > an acceptable band-aid for now?
    >
    > This is going to make it print two warnings for one occurrence of the
    > problem though. I'd much prefer to put something into minstrel.c to
    > catch when _it_ returns bogus values and in that case return 0, that way
    > at least the bandaid is restricted to the code it patches up.

    Ok, then maybe something like this?

    I think this covers most of the bases: if the driver is returning crap or
    the ->cb gets corrupted, it'll get caught in tx_status. If minstrel
    stuffs a -1 in the first slot for any other reason we'll get a warning
    before get_tx_rate and a hopefully valid index gets substituted.

    diff --git a/net/mac80211/rc80211_minstrel.c b/net/mac80211/rc80211_minstrel.c
    index 3824990..1cf7152 100644
    --- a/net/mac80211/rc80211_minstrel.c
    +++ b/net/mac80211/rc80211_minstrel.c
    @@ -181,6 +181,11 @@ minstrel_tx_status(void *priv, struct ieee80211_supported_band *sband,
    if (ar[i].idx < 0)
    break;

    + if (WARN(ar[i].idx >= mi->n_rates,
    + "minstrel: invalid rate report %d (n=%d)\n",
    + ar[i].idx, mi->n_rates))
    + break;
    +
    ndx = rix_to_ndx(mi, ar[i].idx);
    mi->r[ndx].attempts += ar[i].count;

    @@ -328,7 +333,7 @@ minstrel_get_rate(void *priv, struct ieee80211_sta *sta,
    ar[0].count = mp->max_retry;
    ar[1].idx = mi->lowest_rix;
    ar[1].count = mp->max_retry;
    - return;
    + goto done;
    }

    /* MRR setup */
    @@ -346,6 +351,10 @@ minstrel_get_rate(void *priv, struct ieee80211_sta *sta,
    ar[i].idx = mi->r[mrr_ndx[i - 1]].rix;
    ar[i].count = mi->r[mrr_ndx[i - 1]].adjusted_retry_count;
    }
    +
    +done:
    + if (WARN_ON(ar[0].idx < 0))
    + ar[0].idx = rate_lowest_index(sband, sta);
    }


    --
    Bob Copeland %% www.bobcopeland.com



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