| Message ID | d67c1a6772d46f449dbb74d61ddf4d80dee7a350.1535489707.git.lorenzo.bianconi@redhat.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Johannes Berg |
| Headers | show |
| Series | mac80211: do not aggregate frames if max_frags is set to one | expand |
On Tue, 2018-08-28 at 23:07 +0200, Lorenzo Bianconi wrote: > Do not try to aggregate packets in a A-MSDU frame if max_tx_fragments > or max_amsdu_subframes is set to 1. Yeah that seems valid. > Moreover take into account > tail padding added on the first frame into flow backlog if > ieee80211_amsdu_realloc_pad routine on the second frame fails. That's not really right - the padding shouldn't have been added to the first subframe in the first place as the last one shouldn't have padding at all. There's also a separate bug in that the A-MSDU subframe length should NOT include the padding. My colleague Sara (CC'ed now) has a patch to fix all of this (we just did that this morning). I'll send it out tomorrow morning. Can I bother you to try that? We'd have to fix the first point independently though, or I guess we can roll that into our bugfix too, which would you prefer? johannes
> > On Tue, 2018-08-28 at 23:07 +0200, Lorenzo Bianconi wrote: > > Do not try to aggregate packets in a A-MSDU frame if max_tx_fragments > > or max_amsdu_subframes is set to 1. > > Yeah that seems valid. > > > Moreover take into account > > tail padding added on the first frame into flow backlog if > > ieee80211_amsdu_realloc_pad routine on the second frame fails. > > That's not really right - the padding shouldn't have been added to the > first subframe in the first place as the last one shouldn't have padding > at all. There's also a separate bug in that the A-MSDU subframe length > should NOT include the padding. > Assuming the A-MSDU subframe is composed by two packets, the last one must not contain padding, is my understanding correct? > My colleague Sara (CC'ed now) has a patch to fix all of this (we just > did that this morning). I'll send it out tomorrow morning. Can I bother > you to try that? > Sure, no worries :) > We'd have to fix the first point independently though, or I guess we can > roll that into our bugfix too, which would you prefer? > > johannes > If the patch is already done I can add the fix for the first point on top of it, does it sound good? Regards, Lorenzo
On Tue, 2018-08-28 at 23:41 +0200, Lorenzo Bianconi wrote: > Assuming the A-MSDU subframe is composed by two packets, the last one > must not contain padding, is my understanding correct? Yes. More generally, assuming the A-MSDU subframe is composed of *any number of* packets, the last one must not contain padding :) > > My colleague Sara (CC'ed now) has a patch to fix all of this (we just > > did that this morning). I'll send it out tomorrow morning. Can I bother > > you to try that? > > > > Sure, no worries :) Thanks, patch coming up in a second. > > We'd have to fix the first point independently though, or I guess we can > > roll that into our bugfix too, which would you prefer? > > > > johannes > > > > If the patch is already done I can add the fix for the first point on > top of it, does it sound good? Perfect. johannes
> On Tue, 2018-08-28 at 23:41 +0200, Lorenzo Bianconi wrote: > > > Assuming the A-MSDU subframe is composed by two packets, the last one > > must not contain padding, is my understanding correct? > > Yes. More generally, assuming the A-MSDU subframe is composed of *any > number of* packets, the last one must not contain padding :) > > > > My colleague Sara (CC'ed now) has a patch to fix all of this (we just > > > did that this morning). I'll send it out tomorrow morning. Can I bother > > > you to try that? > > > > > > > Sure, no worries :) > > Thanks, patch coming up in a second. > > > > We'd have to fix the first point independently though, or I guess we can > > > roll that into our bugfix too, which would you prefer? > > > > > > johannes > > > > > > > If the patch is already done I can add the fix for the first point on > > top of it, does it sound good? > > Perfect. Ok, I will apply it on top of Sara's patch and send it later today. Regards, Lorenzo > > johannes
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c index 093108077edc..a5701573c83b 100644 --- a/net/mac80211/tx.c +++ b/net/mac80211/tx.c @@ -3185,11 +3185,11 @@ static bool ieee80211_amsdu_aggregate(struct ieee80211_sub_if_data *sdata, u8 max_subframes = sta->sta.max_amsdu_subframes; int max_frags = local->hw.max_tx_fragments; int max_amsdu_len = sta->sta.max_amsdu_len; + int n = 1, nfrags, delta; __be16 len; void *data; bool ret = false; unsigned int orig_len; - int n = 1, nfrags; if (!ieee80211_hw_check(&local->hw, TX_AMSDU)) return false; @@ -3222,9 +3222,6 @@ static bool ieee80211_amsdu_aggregate(struct ieee80211_sub_if_data *sdata, if (skb->len + head->len > max_amsdu_len) goto out; - if (!ieee80211_amsdu_prepare_head(sdata, fast_tx, head)) - goto out; - nfrags = 1 + skb_shinfo(skb)->nr_frags; nfrags += 1 + skb_shinfo(head)->nr_frags; frag_tail = &skb_shinfo(head)->frag_list; @@ -3240,10 +3237,15 @@ static bool ieee80211_amsdu_aggregate(struct ieee80211_sub_if_data *sdata, if (max_frags && nfrags > max_frags) goto out; - if (!ieee80211_amsdu_realloc_pad(local, skb, sizeof(rfc1042_header) + 2, - &subframe_len)) + if (!ieee80211_amsdu_prepare_head(sdata, fast_tx, head)) goto out; + if (!ieee80211_amsdu_realloc_pad(local, skb, sizeof(rfc1042_header) + 2, + &subframe_len)) { + delta = head->len - orig_len; + goto update_backlog; + } + ret = true; data = skb_push(skb, ETH_ALEN + 2); memmove(data, data + ETH_ALEN + 2, 2 * ETH_ALEN); @@ -3256,11 +3258,14 @@ static bool ieee80211_amsdu_aggregate(struct ieee80211_sub_if_data *sdata, head->len += skb->len; head->data_len += skb->len; *frag_tail = skb; + delta = head->len - orig_len; - flow->backlog += head->len - orig_len; - tin->backlog_bytes += head->len - orig_len; - - fq_recalc_backlog(fq, tin, flow); +update_backlog: + if (delta > 0) { + flow->backlog += delta; + tin->backlog_bytes += delta; + fq_recalc_backlog(fq, tin, flow); + } out: spin_unlock_bh(&fq->lock);
Do not try to aggregate packets in a A-MSDU frame if max_tx_fragments or max_amsdu_subframes is set to 1. Moreover take into account tail padding added on the first frame into flow backlog if ieee80211_amsdu_realloc_pad routine on the second frame fails. This patch fixes a kernel freeze that occasionally occurs running iperf tests using mt76 driver Fixes: 6e0456b54545 ("mac80211: add A-MSDU tx support") Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com> --- net/mac80211/tx.c | 25 +++++++++++++++---------- 1 file changed, 15 insertions(+), 10 deletions(-)