dmaengine: kill some dubious WARN_ONCEs

dma_find_channel and dma_issue_pending_all are good places to warn about
improper api usage.  However, warning correctly means synchronizing with
dma_list_mutex, i.e. too much overhead for these fast-path calls.

Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index 6df144a..a589930 100644 (file)
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -329,9 +329,6 @@ struct dma_chan *dma_find_channel(enum dma_transaction_type tx_type)
        struct dma_chan *chan;
        int cpu;
 
-       WARN_ONCE(dmaengine_ref_count == 0,
-                 "client called %s without a reference", __func__);
-
        cpu = get_cpu();
        chan = per_cpu_ptr(channel_table[tx_type], cpu)->chan;
        put_cpu();
@@ -348,9 +345,6 @@ void dma_issue_pending_all(void)
        struct dma_device *device;
        struct dma_chan *chan;
 
-       WARN_ONCE(dmaengine_ref_count == 0,
-                 "client called %s without a reference", __func__);
-
        rcu_read_lock();
        list_for_each_entry_rcu(device, &dma_device_list, global_node) {
                if (dma_has_cap(DMA_PRIVATE, device->cap_mask))