From 6f49a57aa5a0c6d4e4e27c85f7af6c83325a12d1 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Tue, 6 Jan 2009 11:38:14 -0700 Subject: 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 Acked-by: Maciej Sosnowski Signed-off-by: Dan Williams --- include/net/netdma.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'include/net') diff --git a/include/net/netdma.h b/include/net/netdma.h index f28c6e064e8f..cbe2737f4a61 100644 --- a/include/net/netdma.h +++ b/include/net/netdma.h @@ -27,11 +27,11 @@ static inline struct dma_chan *get_softnet_dma(void) { struct dma_chan *chan; + rcu_read_lock(); chan = rcu_dereference(__get_cpu_var(softnet_data).net_dma); - if (chan) - dma_chan_get(chan); rcu_read_unlock(); + return chan; } -- cgit v1.2.3 From f67b45999205164958de4ec0658d51fa4bee066d Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Tue, 6 Jan 2009 11:38:15 -0700 Subject: net_dma: convert to dma_find_channel Use the general-purpose channel allocation provided by dmaengine. Reviewed-by: Andrew Morton Signed-off-by: Dan Williams --- include/net/netdma.h | 11 ----------- 1 file changed, 11 deletions(-) (limited to 'include/net') diff --git a/include/net/netdma.h b/include/net/netdma.h index cbe2737f4a61..8ba8ce284eeb 100644 --- a/include/net/netdma.h +++ b/include/net/netdma.h @@ -24,17 +24,6 @@ #include #include -static inline struct dma_chan *get_softnet_dma(void) -{ - struct dma_chan *chan; - - rcu_read_lock(); - chan = rcu_dereference(__get_cpu_var(softnet_data).net_dma); - rcu_read_unlock(); - - return chan; -} - int dma_skb_copy_datagram_iovec(struct dma_chan* chan, struct sk_buff *skb, int offset, struct iovec *to, size_t len, struct dma_pinned_list *pinned_list); -- cgit v1.2.3