[opencloudos:linux-5.4/next 26765/27506] kernel/sched/fair.c:4147:9: warning: listing the stack pointer register 'rsp' in a clobber list is deprecated

[kernel test robot <lkp@intel.com>]

tree:   https://gitee.com/OpenCloudOS/OpenCloudOS-Kernel.git linux-5.4/next
head:   3ba333344123321f5f312e69966bbc8e5533561f
commit: 67c4700e9b94fcd3b84cfa8ed42e5a130ac619e9 [26765/27506] sched: using rbp to restore rsp when exit dequeue_entity
config: x86_64-buildonly-randconfig-003-20240305 (https://download.01.org/0day-ci/archive/20240312/202403120326.vbFOILVL-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240312/202403120326.vbFOILVL-lkp@intel.com/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@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202403120326.vbFOILVL-lkp@intel.com/

All warnings (new ones prefixed by >>):

   kernel/sched/fair.c:4851:5: warning: no previous prototype for 'runtime_refresh_within' [-Wmissing-prototypes]
    4851 | int runtime_refresh_within(struct cfs_bandwidth *cfs_b, u64 min_expire)
         |     ^~~~~~~~~~~~~~~~~~~~~~
   kernel/sched/fair.c:4868:6: warning: no previous prototype for 'start_cfs_slack_bandwidth' [-Wmissing-prototypes]
    4868 | void start_cfs_slack_bandwidth(struct cfs_bandwidth *cfs_b)
         |      ^~~~~~~~~~~~~~~~~~~~~~~~~
   kernel/sched/fair.c: In function 'dequeue_entity':
>> kernel/sched/fair.c:4147:9: warning: listing the stack pointer register 'rsp' in a clobber list is deprecated [-Wdeprecated]
    4147 |         asm volatile("" : : : "rsp");
         |         ^~~
   kernel/sched/fair.c:4147:9: note: the value of the stack pointer after an 'asm' statement must be the same as it was before the statement


vim +/rsp +4147 kernel/sched/fair.c

  4093	
  4094	static void
  4095	dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
  4096	{
  4097		/*
  4098		 * Update run-time statistics of the 'current'.
  4099		 */
  4100		update_curr(cfs_rq);
  4101	
  4102		/*
  4103		 * When dequeuing a sched_entity, we must:
  4104		 *   - Update loads to have both entity and cfs_rq synced with now.
  4105		 *   - Subtract its load from the cfs_rq->runnable_avg.
  4106		 *   - Subtract its previous weight from cfs_rq->load.weight.
  4107		 *   - For group entity, update its weight to reflect the new share
  4108		 *     of its group cfs_rq.
  4109		 */
  4110		update_load_avg(cfs_rq, se, UPDATE_TG);
  4111		dequeue_runnable_load_avg(cfs_rq, se);
  4112	
  4113		update_stats_dequeue(cfs_rq, se, flags);
  4114	
  4115		clear_buddies(cfs_rq, se);
  4116	
  4117		if (se != cfs_rq->curr)
  4118			__dequeue_entity(cfs_rq, se);
  4119		se->on_rq = 0;
  4120		account_entity_dequeue(cfs_rq, se);
  4121	
  4122		/*
  4123		 * Normalize after update_curr(); which will also have moved
  4124		 * min_vruntime if @se is the one holding it back. But before doing
  4125		 * update_min_vruntime() again, which will discount @se's position and
  4126		 * can move min_vruntime forward still more.
  4127		 */
  4128		if (!(flags & DEQUEUE_SLEEP))
  4129			se->vruntime -= cfs_rq->min_vruntime;
  4130	
  4131		/* return excess runtime on last dequeue */
  4132		return_cfs_rq_runtime(cfs_rq);
  4133	
  4134		update_cfs_group(se);
  4135	
  4136		/*
  4137		 * Now advance min_vruntime if @se was the entity holding it back,
  4138		 * except when: DEQUEUE_SAVE && !DEQUEUE_MOVE, in this case we'll be
  4139		 * put back on, and if we advance min_vruntime, we'll be placed back
  4140		 * further than we started -- ie. we'll be penalized.
  4141		 */
  4142		if ((flags & (DEQUEUE_SAVE | DEQUEUE_MOVE)) != DEQUEUE_SAVE)
  4143			update_min_vruntime(cfs_rq);
  4144	
  4145	#ifdef	CONFIG_X86_64
  4146		/* Declare rsp register is destroyed, let gcc using rbp to restore rsp. */
> 4147		asm volatile("" : : : "rsp");
  4148	#endif
  4149	}
  4150	

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