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authorAnton Vorontsov <avorontsov@ru.mvista.com>2010-03-03 08:18:58 +0000
committerDavid S. Miller <davem@davemloft.net>2010-03-04 00:53:53 -0800
commit0eddba525cf4c3a4aab9feaf36b12b465290d4a7 (patch)
treeb41b9a6ba53635c1c7137bc0993e4c7f03ef721b /drivers/net/cxgb3
parent4c020a961a812ffae9846b917304cea504c3a733 (diff)
gianfar: Fix TX ring processing on SMP machines
Starting with commit a3bc1f11e9b867a4f49505 ("gianfar: Revive SKB recycling") gianfar driver sooner or later stops transmitting any packets on SMP machines. start_xmit() prepares new skb for transmitting, generally it does three things: 1. sets up all BDs (marks them ready to send), except the first one. 2. stores skb into tx_queue->tx_skbuff so that clean_tx_ring() would cleanup it later. 3. sets up the first BD, i.e. marks it ready. Here is what clean_tx_ring() does: 1. reads skbs from tx_queue->tx_skbuff 2. checks if the *last* BD is ready. If it's still ready [to send] then it it isn't transmitted, so clean_tx_ring() returns. Otherwise it actually cleanups BDs. All is OK. Now, if there is just one BD, code flow: - start_xmit(): stores skb into tx_skbuff. Note that the first BD (which is also the last one) isn't marked as ready, yet. - clean_tx_ring(): sees that skb is not null, *and* its lstatus says that it is NOT ready (like if BD was sent), so it cleans it up (bad!) - start_xmit(): marks BD as ready [to send], but it's too late. We can fix this simply by reordering lstatus/tx_skbuff writes. Reported-by: Martyn Welch <martyn.welch@ge.com> Bisected-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com> Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com> Tested-by: Martyn Welch <martyn.welch@ge.com> Cc: Sandeep Gopalpet <Sandeep.Kumar@freescale.com> Cc: Stable <stable@vger.kernel.org> [2.6.33] Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/cxgb3')
0 files changed, 0 insertions, 0 deletions