lkml.org 
[lkml]   [2013]   [Jun]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [PATCH] mac80211: Use RCU protection in ieee80211_get_tx_rates()
On 2013-06-12 10:00 AM, Calvin Owens wrote:
> Copying the rate table should be done in an RCU read-side critical
> section.
I think this approach is wrong. The sta entry is also under RCU
protection (no locking for read access in that part of the code.
In a normal driver tx path, no extra rcu_read_lock/rcu_read_unlock is
needed. Only if the driver does some scheduling outside of the tx
function (which ath9k does), this RCU warning appears.

How about this change instead:
---
--- a/drivers/net/wireless/ath/ath9k/xmit.c
+++ b/drivers/net/wireless/ath/ath9k/xmit.c
@@ -1570,6 +1570,8 @@ void ath_txq_schedule(struct ath_softc *
txq->axq_ampdu_depth >= ATH_AGGR_MIN_QDEPTH)
return;

+ rcu_read_lock();
+
ac = list_first_entry(&txq->axq_acq, struct ath_atx_ac, list);
last_ac = list_entry(txq->axq_acq.prev, struct ath_atx_ac, list);

@@ -1608,8 +1610,10 @@ void ath_txq_schedule(struct ath_softc *

if (ac == last_ac ||
txq->axq_ampdu_depth >= ATH_AGGR_MIN_QDEPTH)
- return;
+ break;
}
+
+ rcu_read_unlock();
}

/***********/


\
 
 \ /
  Last update: 2013-06-12 12:01    [W:0.057 / U:0.056 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site