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authorDan Williams <dan.j.williams@intel.com>2009-07-14 12:19:02 -0700
committerDan Williams <dan.j.williams@intel.com>2009-08-29 19:09:27 -0700
commit95475e57113c66aac7583925736ed2e2d58c990d (patch)
tree933aa0ca3bffef5b1457c516fbe3e8690b4c4cb1 /include/linux/async_tx.h
parentaf1f951eb6ef27b01cbfb3f6c21b770af4368a6d (diff)
downloadop-kernel-dev-95475e57113c66aac7583925736ed2e2d58c990d.zip
op-kernel-dev-95475e57113c66aac7583925736ed2e2d58c990d.tar.gz
async_tx: remove walk of tx->parent chain in dma_wait_for_async_tx
We currently walk the parent chain when waiting for a given tx to complete however this walk may race with the driver cleanup routine. The routines in async_raid6_recov.c may fall back to the synchronous path at any point so we need to be prepared to call async_tx_quiesce() (which calls dma_wait_for_async_tx). To remove the ->parent walk we guarantee that every time a dependency is attached ->issue_pending() is invoked, then we can simply poll the initial descriptor until completion. This also allows for a lighter weight 'issue pending' implementation as there is no longer a requirement to iterate through all the channels' ->issue_pending() routines as long as operations have been submitted in an ordered chain. async_tx_issue_pending() is added for this case. Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'include/linux/async_tx.h')
-rw-r--r--include/linux/async_tx.h23
1 files changed, 23 insertions, 0 deletions
diff --git a/include/linux/async_tx.h b/include/linux/async_tx.h
index 3d21a25..12a2efc 100644
--- a/include/linux/async_tx.h
+++ b/include/linux/async_tx.h
@@ -83,6 +83,24 @@ struct async_submit_ctl {
#ifdef CONFIG_DMA_ENGINE
#define async_tx_issue_pending_all dma_issue_pending_all
+
+/**
+ * async_tx_issue_pending - send pending descriptor to the hardware channel
+ * @tx: descriptor handle to retrieve hardware context
+ *
+ * Note: any dependent operations will have already been issued by
+ * async_tx_channel_switch, or (in the case of no channel switch) will
+ * be already pending on this channel.
+ */
+static inline void async_tx_issue_pending(struct dma_async_tx_descriptor *tx)
+{
+ if (likely(tx)) {
+ struct dma_chan *chan = tx->chan;
+ struct dma_device *dma = chan->device;
+
+ dma->device_issue_pending(chan);
+ }
+}
#ifdef CONFIG_ARCH_HAS_ASYNC_TX_FIND_CHANNEL
#include <asm/async_tx.h>
#else
@@ -98,6 +116,11 @@ static inline void async_tx_issue_pending_all(void)
do { } while (0);
}
+static inline void async_tx_issue_pending(struct dma_async_tx_descriptor *tx)
+{
+ do { } while (0);
+}
+
static inline struct dma_chan *
async_tx_find_channel(struct async_submit_ctl *submit,
enum dma_transaction_type tx_type, struct page **dst,
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