Re: [PATCH v2 0/2] kernfs, sysfs: refuse splice on /sys/power/resume

[Krystian Kaniewski <krystianmkaniewski@gmail.com>]

On 11/3/26 16:51, Tejun Heo wrote:
> Hello, Krystian.
> 
> On Tue, Nov 03, 2026 at 03:57:41PM +0100, Krystian Kaniewski wrote:
>> Patch 1 adds SYSFS_LOOKUP and kernfs_ops->may_lookup. Writable opens of a
>> marked file refuse both splice directions. Their of->mutex and seq_file lock
>> use separate classes. Read-only opens retain splice support.
> 
> Can we be explicit and name the flag after what it does, e.g.
> SYSFS_NO_SPLICE and kernfs_ops->no_splice?
> 

Yes, that is clearer. I renamed the flag to SYSFS_NO_SPLICE and the
kernfs_ops member to no_splice in v3.

>> The new property cannot be combined with mmap or preallocated buffers.
>> Kernfs rejects those combinations for direct callers, and sysfs rejects
>> SYSFS_LOOKUP together with SYSFS_PREALLOC before selecting operations.
>> Binary attributes do not support SYSFS_LOOKUP and reject it at creation.
> 
> Can we keep the rest minimal? With /sys/power/resume the only user, I don't
> think things like the mmap and prealloc combination checks or the binary
> attribute rejections are needed.
> 
> Thanks.
> 
> --
> tejun

Agreed. I dropped the mmap and prealloc combination checks and the binary
attribute rejections. /sys/power/resume remains the only user.

I'll send v3 shortly with these changes.

Thanks,
-- 
Krystian Kaniewski