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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