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authorDan Williams <dan.j.williams@intel.com>2009-01-06 13:38:14 -0500
committerDan Williams <dan.j.williams@intel.com>2009-01-06 13:38:14 -0500
commit6f49a57aa5a0c6d4e4e27c85f7af6c83325a12d1 (patch)
treeafba24357d1f4ff69ccb2b39a19542546590a50b /net/ipv4/tcp.c
parent07f2211e4fbce6990722d78c4f04225da9c0e9cf (diff)
dmaengine: up-level reference counting to the module level
Simply, if a client wants any dmaengine channel then prevent all dmaengine modules from being removed. Once the clients are done re-enable module removal. Why?, beyond reducing complication: 1/ Tracking reference counts per-transaction in an efficient manner, as is currently done, requires a complicated scheme to avoid cache-line bouncing effects. 2/ Per-transaction ref-counting gives the false impression that a dma-driver can be gracefully removed ahead of its user (net, md, or dma-slave) 3/ None of the in-tree dma-drivers talk to hot pluggable hardware, but if such an engine were built one day we still would not need to notify clients of remove events. The driver can simply return NULL to a ->prep() request, something that is much easier for a client to handle. Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Maciej Sosnowski <maciej.sosnowski@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'net/ipv4/tcp.c')
-rw-r--r--net/ipv4/tcp.c1
1 files changed, 0 insertions, 1 deletions
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index f28acf11fc67..75e0e0a2d8db 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1632,7 +1632,6 @@ skip_copy:
1632 1632
1633 /* Safe to free early-copied skbs now */ 1633 /* Safe to free early-copied skbs now */
1634 __skb_queue_purge(&sk->sk_async_wait_queue); 1634 __skb_queue_purge(&sk->sk_async_wait_queue);
1635 dma_chan_put(tp->ucopy.dma_chan);
1636 tp->ucopy.dma_chan = NULL; 1635 tp->ucopy.dma_chan = NULL;
1637 } 1636 }
1638 if (tp->ucopy.pinned_list) { 1637 if (tp->ucopy.pinned_list) {