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    Subject[PATCH 1/3] dmaengine: intel_mid_dma: locking and freeing fixes
    Date
    Two issues are fixed:

    1. DMA descriptors are reused so when freeing lli structures
    that are linked to them, the pointer must be nulled.

    2. midc_scan_descriptors() must be called with the
    channel lock held.

    Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
    ---
    drivers/dma/intel_mid_dma.c | 7 ++++++-
    1 files changed, 6 insertions(+), 1 deletions(-)

    diff --git a/drivers/dma/intel_mid_dma.c b/drivers/dma/intel_mid_dma.c
    index 01929ed..d4b9616 100644
    --- a/drivers/dma/intel_mid_dma.c
    +++ b/drivers/dma/intel_mid_dma.c
    @@ -280,7 +280,8 @@ static void midc_dostart(struct intel_mid_dma_chan *midc,
    * callbacks but must be called with the lock held.
    */
    static void midc_descriptor_complete(struct intel_mid_dma_chan *midc,
    - struct intel_mid_dma_desc *desc)
    + struct intel_mid_dma_desc *desc)
    + __releases(&midc->lock) __acquires(&midc->lock)
    {
    struct dma_async_tx_descriptor *txd = &desc->txd;
    dma_async_tx_callback callback_txd = NULL;
    @@ -311,6 +312,7 @@ static void midc_descriptor_complete(struct intel_mid_dma_chan *midc,
    pci_pool_free(desc->lli_pool, desc->lli,
    desc->lli_phys);
    pci_pool_destroy(desc->lli_pool);
    + desc->lli = NULL;
    }
    list_move(&desc->desc_node, &midc->free_list);
    midc->busy = false;
    @@ -490,7 +492,9 @@ static enum dma_status intel_mid_dma_tx_status(struct dma_chan *chan,

    ret = dma_async_is_complete(cookie, last_complete, last_used);
    if (ret != DMA_SUCCESS) {
    + spin_lock_bh(&midc->lock);
    midc_scan_descriptors(to_middma_device(chan->device), midc);
    + spin_unlock_bh(&midc->lock);

    last_complete = midc->completed;
    last_used = chan->cookie;
    @@ -566,6 +570,7 @@ static int intel_mid_dma_device_control(struct dma_chan *chan,
    pci_pool_free(desc->lli_pool, desc->lli,
    desc->lli_phys);
    pci_pool_destroy(desc->lli_pool);
    + desc->lli = NULL;
    }
    list_move(&desc->desc_node, &midc->free_list);
    }
    --
    1.7.6.4


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