Re: [PATCH] sched/deadline: document new sched_getattr() feature for retrieving current parameters for DEADLINE tasks

[kernel test robot]

Hi Tommaso,

kernel test robot noticed the following build warnings:

[auto build test WARNING on f74d204baf9febf96237af6c1d7eff57fba7de36]

url:    https://github.com/intel-lab-lkp/linux/commits/Tommaso-Cucinotta/sched-deadline-document-new-sched_getattr-feature-for-retrieving-current-parameters-for-DEADLINE-tasks/20260303-184545
base:   f74d204baf9febf96237af6c1d7eff57fba7de36
patch link:    https://lore.kernel.org/r/20260303104215.1324243-1-tommaso.cucinotta%40santannapisa.it
patch subject: [PATCH] sched/deadline: document new sched_getattr() feature for retrieving current parameters for DEADLINE tasks
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
docutils: docutils (Docutils 0.21.2, Python 3.13.5, on linux)
reproduce: (https://download.01.org/0day-ci/archive/20260303/202603031858.JyW2vicC-lkp@xxxxxxxxx/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@xxxxxxxxx>
| Closes: https://lore.kernel.org/oe-kbuild-all/202603031858.JyW2vicC-lkp@xxxxxxxxx/

All warnings (new ones prefixed by >>):

   Checksumming on output with GSO
   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ [docutils]
>> Documentation/scheduler/sched-deadline.rst:631: WARNING: Inline interpreted text or phrase reference start-string without end-string. [docutils]
   Documentation/userspace-api/landlock:480: ./security/landlock/errata/abi-4.h:5: ERROR: Unexpected section title.


vim +631 Documentation/scheduler/sched-deadline.rst

   615	
   616	 Specifying a periodic/sporadic task that executes for a given amount of
   617	 runtime at each instance, and that is scheduled according to the urgency of
   618	 its own timing constraints needs, in general, a way of declaring:
   619	
   620	  - a (maximum/typical) instance execution time,
   621	  - a minimum interval between consecutive instances,
   622	  - a time constraint by which each instance must be completed.
   623	
   624	 Therefore:
   625	
   626	  * a new struct sched_attr, containing all the necessary fields is
   627	    provided;
   628	  * the new scheduling related syscalls that manipulate it, i.e.,
   629	    sched_setattr() and sched_getattr() are implemented.
   630	
 > 631	 The leftover runtime and absolute deadline of a SCHED_DEADLINE task can be
   632	 read using the sched_getattr() syscall, setting the last syscall parameter
   633	 `flags' to the SCHED_GETATTR_FLAG_DL_DYNAMIC=1 value. This updates the
   634	 runtime left, converts the absolute deadline in CLOCK_MONOTONIC reference,
   635	 then returns these parameters to user-space. The absolute deadline is
   636	 returned as the number of nanoseconds since the CLOCK_MONOTONIC time
   637	 reference (boot instant), as a u64 in the sched_deadline field of sched_attr,
   638	 which can represent nearly 585 years since boot time (calling sched_getattr()
   639	 with flags=0 causes retrieval of the static parameters instead).
   640	
   641	 For debugging purposes, these parameters can also be retrieved through
   642	 /proc/<pid>/sched (entries dl.runtime and dl.deadline, both values in ns),
   643	 but: this is highly inefficient; the returned runtime left is not updated as
   644	 done by sched_getattr(); the deadline is provided in kernel rq_clock time
   645	 reference, that is not directly usable from user-space.
   646	
   647	

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