From: Dan Williams Date: Fri, 18 Jul 2008 00:59:55 +0000 (-0700) Subject: async_tx: fix handling of the "out of descriptor" condition in async_xor X-Git-Tag: v2.6.27-rc1~852^2~9 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=669ab0b210f9bd15d94d4d6a49ae13366a85e4da;p=linux-2.6 async_tx: fix handling of the "out of descriptor" condition in async_xor Ensure forward progress is made when a dmaengine driver is unable to allocate an xor descriptor by breaking the dependency chain with async_tx_quisce() and issue any pending descriptors. Tested with iop-adma by setting device->max_xor = 2 to force multiple calls to device_prep_dma_xor for each call to async_xor and limiting the descriptor slot pool to 5. Discovered that the minimum descriptor pool size for iop-adma is 2 * iop_chan_xor_slot_cnt(device->max_xor) + 1. Signed-off-by: Dan Williams --- diff --git a/crypto/async_tx/async_xor.c b/crypto/async_tx/async_xor.c index 1fcf45ac81..19d16e452b 100644 --- a/crypto/async_tx/async_xor.c +++ b/crypto/async_tx/async_xor.c @@ -30,6 +30,24 @@ #include #include +/** + * async_tx_quiesce - ensure tx is complete and freeable upon return + * @tx - transaction to quiesce + */ +static void async_tx_quiesce(struct dma_async_tx_descriptor **tx) +{ + if (*tx) { + /* if ack is already set then we cannot be sure + * we are referring to the correct operation + */ + BUG_ON(async_tx_test_ack(*tx)); + if (dma_wait_for_async_tx(*tx) == DMA_ERROR) + panic("DMA_ERROR waiting for transaction\n"); + async_tx_ack(*tx); + *tx = NULL; + } +} + /* do_async_xor - dma map the pages and perform the xor with an engine. * This routine is marked __always_inline so it can be compiled away * when CONFIG_DMA_ENGINE=n @@ -85,15 +103,17 @@ do_async_xor(struct dma_chan *chan, struct page *dest, struct page **src_list, tx = dma->device_prep_dma_xor(chan, dma_dest, &dma_src[src_off], xor_src_cnt, len, dma_flags); - if (unlikely(!tx && depend_tx)) - dma_wait_for_async_tx(depend_tx); + if (unlikely(!tx)) + async_tx_quiesce(&depend_tx); /* spin wait for the preceeding transactions to complete */ - while (unlikely(!tx)) + while (unlikely(!tx)) { + dma_async_issue_pending(chan); tx = dma->device_prep_dma_xor(chan, dma_dest, &dma_src[src_off], xor_src_cnt, len, dma_flags); + } async_tx_submit(chan, tx, async_flags, depend_tx, _cb_fn, _cb_param); @@ -267,11 +287,11 @@ async_xor_zero_sum(struct page *dest, struct page **src_list, tx = device->device_prep_dma_zero_sum(chan, dma_src, src_cnt, len, result, dma_prep_flags); - if (!tx) { - if (depend_tx) - dma_wait_for_async_tx(depend_tx); + if (unlikely(!tx)) { + async_tx_quiesce(&depend_tx); while (!tx) + dma_async_issue_pending(chan); tx = device->device_prep_dma_zero_sum(chan, dma_src, src_cnt, len, result, dma_prep_flags);