Re: [PATCH v2] b43: don't save dentries for debugfs

On Tue, May 18, 2021 at 03:00:44PM -0700, Jeff Johnson wrote:

On 2021-05-18 12:29, Jeff Johnson wrote:

quoted

On 2021-05-18 09:33, Greg Kroah-Hartman wrote:

quoted

There is no need to keep around the dentry pointers for the debugfs
files as they will all be automatically removed when the subdir is
removed.  So save the space and logic involved in keeping them
around by
just getting rid of them entirely.

By doing this change, we remove one of the last in-kernel user that
was
storing the result of debugfs_create_bool(), so that api can be
cleaned
up.

Question not about this specific change, but the general concept
of keeping (or not keeping) dentry pointers. In the ath drivers,
as well as in an out-of-tree driver for Android, we keep a
debugfs dentry pointer to use as a param to relay_open().

Will we still be able to have a dentry pointer for this purpose?
Or better, is there a recommended way to get a dentry pointer
NOT associated with debugfs at all (which would be ideal for
Android where debugfs is disabled).

Answering one of my questions: The dentry passed to relay_open() comes
from debugfs_create_dir() which is expected to return a dentry.

Would still like guidance on if there is a recommended way to get a
dentry not associated with debugfs.

What do you exactly mean by "not associated with debugfs"?

And why are you passing a debugfs dentry to relay_open()?  That feels
really wrong and fragile.

Ideally I want to get rid of the "raw" dentry that debugfs returns to
callers, as it has caused odd problems in the past, but that's a very
long-term project...

thanks,

greg k-h