dmaengine: kill some dubious WARN_ONCEs (83436a05) · Commits · 戴 / test

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>

drivers/dma/dmaengine.c

+0 −6

Original line number	Diff line number	Diff line
		@@ -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))

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