From bec085134e446577a983f17f57d642a88d1af53b Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Tue, 6 Jan 2009 11:38:14 -0700 Subject: dmaengine: centralize channel allocation, introduce dma_find_channel Allowing multiple clients to each define their own channel allocation scheme quickly leads to a pathological situation. For memory-to-memory offload all clients can share a central allocator. This simply moves the existing async_tx allocator to dmaengine with minimal fixups: * async_tx.c:get_chan_ref_by_cap --> dmaengine.c:nth_chan * async_tx.c:async_tx_rebalance --> dmaengine.c:dma_channel_rebalance * split out common code from async_tx.c:__async_tx_find_channel --> dma_find_channel Reviewed-by: Andrew Morton Signed-off-by: Dan Williams --- crypto/async_tx/async_tx.c | 146 ++------------------------------------------- 1 file changed, 4 insertions(+), 142 deletions(-) (limited to 'crypto') diff --git a/crypto/async_tx/async_tx.c b/crypto/async_tx/async_tx.c index 43fe4cbe71e6..b88bb1f608fc 100644 --- a/crypto/async_tx/async_tx.c +++ b/crypto/async_tx/async_tx.c @@ -37,26 +37,11 @@ static struct dma_client async_tx_dma = { /* .cap_mask == 0 defaults to all channels */ }; -/** - * dma_cap_mask_all - enable iteration over all operation types - */ -static dma_cap_mask_t dma_cap_mask_all; - -/** - * chan_ref_percpu - tracks channel allocations per core/opertion - */ -struct chan_ref_percpu { - struct dma_chan_ref *ref; -}; - -static int channel_table_initialized; -static struct chan_ref_percpu *channel_table[DMA_TX_TYPE_END]; - /** * async_tx_lock - protect modification of async_tx_master_list and serialize * rebalance operations */ -static spinlock_t async_tx_lock; +static DEFINE_SPINLOCK(async_tx_lock); static LIST_HEAD(async_tx_master_list); @@ -89,85 +74,6 @@ init_dma_chan_ref(struct dma_chan_ref *ref, struct dma_chan *chan) atomic_set(&ref->count, 0); } -/** - * get_chan_ref_by_cap - returns the nth channel of the given capability - * defaults to returning the channel with the desired capability and the - * lowest reference count if the index can not be satisfied - * @cap: capability to match - * @index: nth channel desired, passing -1 has the effect of forcing the - * default return value - */ -static struct dma_chan_ref * -get_chan_ref_by_cap(enum dma_transaction_type cap, int index) -{ - struct dma_chan_ref *ret_ref = NULL, *min_ref = NULL, *ref; - - rcu_read_lock(); - list_for_each_entry_rcu(ref, &async_tx_master_list, node) - if (dma_has_cap(cap, ref->chan->device->cap_mask)) { - if (!min_ref) - min_ref = ref; - else if (atomic_read(&ref->count) < - atomic_read(&min_ref->count)) - min_ref = ref; - - if (index-- == 0) { - ret_ref = ref; - break; - } - } - rcu_read_unlock(); - - if (!ret_ref) - ret_ref = min_ref; - - if (ret_ref) - atomic_inc(&ret_ref->count); - - return ret_ref; -} - -/** - * async_tx_rebalance - redistribute the available channels, optimize - * for cpu isolation in the SMP case, and opertaion isolation in the - * uniprocessor case - */ -static void async_tx_rebalance(void) -{ - int cpu, cap, cpu_idx = 0; - unsigned long flags; - - if (!channel_table_initialized) - return; - - spin_lock_irqsave(&async_tx_lock, flags); - - /* undo the last distribution */ - for_each_dma_cap_mask(cap, dma_cap_mask_all) - for_each_possible_cpu(cpu) { - struct dma_chan_ref *ref = - per_cpu_ptr(channel_table[cap], cpu)->ref; - if (ref) { - atomic_set(&ref->count, 0); - per_cpu_ptr(channel_table[cap], cpu)->ref = - NULL; - } - } - - for_each_dma_cap_mask(cap, dma_cap_mask_all) - for_each_online_cpu(cpu) { - struct dma_chan_ref *new; - if (NR_CPUS > 1) - new = get_chan_ref_by_cap(cap, cpu_idx++); - else - new = get_chan_ref_by_cap(cap, -1); - - per_cpu_ptr(channel_table[cap], cpu)->ref = new; - } - - spin_unlock_irqrestore(&async_tx_lock, flags); -} - static enum dma_state_client dma_channel_add_remove(struct dma_client *client, struct dma_chan *chan, enum dma_state state) @@ -211,8 +117,6 @@ dma_channel_add_remove(struct dma_client *client, " (-ENOMEM)\n"); return 0; } - - async_tx_rebalance(); break; case DMA_RESOURCE_REMOVED: found = 0; @@ -233,8 +137,6 @@ dma_channel_add_remove(struct dma_client *client, ack = DMA_ACK; else break; - - async_tx_rebalance(); break; case DMA_RESOURCE_SUSPEND: case DMA_RESOURCE_RESUME: @@ -248,51 +150,18 @@ dma_channel_add_remove(struct dma_client *client, return ack; } -static int __init -async_tx_init(void) +static int __init async_tx_init(void) { - enum dma_transaction_type cap; - - spin_lock_init(&async_tx_lock); - bitmap_fill(dma_cap_mask_all.bits, DMA_TX_TYPE_END); - - /* an interrupt will never be an explicit operation type. - * clearing this bit prevents allocation to a slot in 'channel_table' - */ - clear_bit(DMA_INTERRUPT, dma_cap_mask_all.bits); - - for_each_dma_cap_mask(cap, dma_cap_mask_all) { - channel_table[cap] = alloc_percpu(struct chan_ref_percpu); - if (!channel_table[cap]) - goto err; - } - - channel_table_initialized = 1; dma_async_client_register(&async_tx_dma); dma_async_client_chan_request(&async_tx_dma); printk(KERN_INFO "async_tx: api initialized (async)\n"); return 0; -err: - printk(KERN_ERR "async_tx: initialization failure\n"); - - while (--cap >= 0) - free_percpu(channel_table[cap]); - - return 1; } static void __exit async_tx_exit(void) { - enum dma_transaction_type cap; - - channel_table_initialized = 0; - - for_each_dma_cap_mask(cap, dma_cap_mask_all) - if (channel_table[cap]) - free_percpu(channel_table[cap]); - dma_async_client_unregister(&async_tx_dma); } @@ -308,16 +177,9 @@ __async_tx_find_channel(struct dma_async_tx_descriptor *depend_tx, { /* see if we can keep the chain on one channel */ if (depend_tx && - dma_has_cap(tx_type, depend_tx->chan->device->cap_mask)) + dma_has_cap(tx_type, depend_tx->chan->device->cap_mask)) return depend_tx->chan; - else if (likely(channel_table_initialized)) { - struct dma_chan_ref *ref; - int cpu = get_cpu(); - ref = per_cpu_ptr(channel_table[tx_type], cpu)->ref; - put_cpu(); - return ref ? ref->chan : NULL; - } else - return NULL; + return dma_find_channel(tx_type); } EXPORT_SYMBOL_GPL(__async_tx_find_channel); #else -- cgit v1.2.3-59-g8ed1b