Re: [PATCH v3 0/3] debugfs: make debugfs_create_str() read-only

[Greg KH]

On Thu, Oct 01, 2026 at 03:10:45PM +0200, Danilo Krummrich wrote:
> On Thu Oct 1, 2026 at 2:51 PM CEST, Greg KH wrote:
> > On Fri, Aug 07, 2026 at 06:00:50PM +0800, Yichong Chen wrote:
> >> debugfs_create_str() has a generic write implementation that replaces the
> >> backing string.  Concurrent writers can race and free the same old string
> >> twice.
> >> 
> >> Instead of adding more locking to the generic helper, convert the existing
> >> writable in-tree users to local file operations and make
> >> debugfs_create_str() read-only.
> >> 
> >> Changes since v2:
> >> - Use scoped mutex guards in the interconnect and SoundWire conversions.
> >> - Clarify why GFP_KERNEL is safe in the interconnect conversion after the
> >>   RCU read-side critical section is removed.
> >> - Drop the unnecessary firmware_file = NULL assignment in the SoundWire
> >>   exit path.
> >> - Use WARN() instead of WARN_ONCE() so each writable debugfs_create_str()
> >>   caller can be reported.
> >
> > Sorry for the delay, now applied.
> 
> This series fell through the cracks on my end. I also reported this issue in [1]
> and I agree making debugfs_create_str() read-only is the best fix for now.
> 
> However, it duplicates code and I think having a proper helper as suggested in
> [1] would be nice follow-up.
> 
> [1] https://lore.kernel.org/driver-core/DLPDB44JJRGJ.3K6JNS746M7QC@xxxxxxxxxx/

Yes, that would be nice, but for read-only debugfs strings, let's keep
writable ones away if at all possible :)

thanks,

greg k-h