Hello, Tejun.
On 19/05/14 23:17, Tejun Heo wrote:
What can't it just do the following?
if (dma_mapping_error(dev, dma_handle)) {
devres_free(dr);
return dma_handle;
}
The caller would have to invoke dma_mapping_error() again but is that
a problem?
That seems OK to me, but the problem I'm concerned with is this: In
devm_get_free_pages() it says
devres = devres_alloc(devm_pages_release,
sizeof(struct pages_devres), GFP_KERNEL);
if (unlikely(!devres)) {
free_pages(addr, order);
return 0;
}
What should I put instead of this "return 0" to conform with the current
API?
And to make things even worse, on some architectures,
dma_mapping_error() always returns success, regardless of dma_handle. So
if we stick to the current API, the caller of devm_get_free_pages() will
never know it failed on these architectures.
So my conclusion was that the caller must be aware that if
devm_get_free_pages() returns zero it's an error, regardless of
dma_mapping_error(). That breaks the API. Once it's broken, why not
return zero on all possible errors?
Maybe I didn't understand what you suggested.
Regards,
Eli
Thanks.
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