Re: [PATCH v5 05/16] swiotlb: Add restricted DMA pool initialization

On 26/04/2021 17:37, Claire Chang wrote:

On Fri, Apr 23, 2021 at 7:34 PM Steven Price [off-list ref] wrote:

[...]

quoted

But even then if it's not and we have the situation where debugfs==NULL
then the debugfs_create_dir() here will cause a subsequent attempt in
swiotlb_create_debugfs() to fail (directory already exists) leading to
mem->debugfs being assigned an error value. I suspect the creation of
the debugfs directory needs to be separated from io_tlb_default_mem
being set.

debugfs creation should move into the if (!mem) {...} above to avoid
duplication.
I think having a separated struct dentry pointer for the default
debugfs should be enough?

if (!debugfs)
     debugfs = debugfs_create_dir("swiotlb", NULL);
swiotlb_create_debugfs(mem, rmem->name, debugfs);

Yes that looks like a good solution to me. Although I'd name the 
variable something a bit more descriptive than just "debugfs" e.g. 
"debugfs_dir" or "debugfs_root".

Thanks,

Steve