[android-common:android-mainline-riscv64 2/2] kernel/sched/core.c:6861:4: error: call to undeclared function 'stack_trace_save_tsk'; ISO C99 and later do not support implicit function declarations

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

tree:   https://android.googlesource.com/kernel/common android-mainline-riscv64
head:   1f36e6de55f3acb717f090d6aa7ab10240b9a2a2
commit: 45072073741a05cd16f4c1f65c647c90c1ed4446 [2/2] ANDROID: Fix invalid caller output in trace_sched_blocked_reason
config: arm-mps2_defconfig (https://download.01.org/0day-ci/archive/20250227/202502272242.HMnIRB86-lkp@intel.com/config)
compiler: clang version 15.0.7 (https://github.com/llvm/llvm-project 8dfdcc7b7bf66834a761bd8de445840ef68e4d1a)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250227/202502272242.HMnIRB86-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/202502272242.HMnIRB86-lkp@intel.com/

All errors (new ones prefixed by >>):

>> kernel/sched/core.c:6861:4: error: call to undeclared function 'stack_trace_save_tsk'; ISO C99 and later do not support implicit function declarations [-Werror,-Wimplicit-function-declaration]
                           stack_trace_save_tsk(prev, &blocked_func, 1, 0);
                           ^
   1 error generated.


vim +/stack_trace_save_tsk +6861 kernel/sched/core.c

  6818	
  6819		trace_android_rvh_schedule(prev, next, rq);
  6820		if (likely(prev != next)) {
  6821			rq->nr_switches++;
  6822			/*
  6823			 * RCU users of rcu_dereference(rq->curr) may not see
  6824			 * changes to task_struct made by pick_next_task().
  6825			 */
  6826			RCU_INIT_POINTER(rq->curr, next);
  6827			/*
  6828			 * The membarrier system call requires each architecture
  6829			 * to have a full memory barrier after updating
  6830			 * rq->curr, before returning to user-space.
  6831			 *
  6832			 * Here are the schemes providing that barrier on the
  6833			 * various architectures:
  6834			 * - mm ? switch_mm() : mmdrop() for x86, s390, sparc, PowerPC,
  6835			 *   RISC-V.  switch_mm() relies on membarrier_arch_switch_mm()
  6836			 *   on PowerPC and on RISC-V.
  6837			 * - finish_lock_switch() for weakly-ordered
  6838			 *   architectures where spin_unlock is a full barrier,
  6839			 * - switch_to() for arm64 (weakly-ordered, spin_unlock
  6840			 *   is a RELEASE barrier),
  6841			 *
  6842			 * The barrier matches a full barrier in the proximity of
  6843			 * the membarrier system call entry.
  6844			 *
  6845			 * On RISC-V, this barrier pairing is also needed for the
  6846			 * SYNC_CORE command when switching between processes, cf.
  6847			 * the inline comments in membarrier_arch_switch_mm().
  6848			 */
  6849			++*switch_count;
  6850	
  6851			migrate_disable_switch(rq, prev);
  6852			psi_account_irqtime(rq, prev, next);
  6853			psi_sched_switch(prev, next, block);
  6854	
  6855			trace_sched_switch(preempt, prev, next, prev_state);
  6856	
  6857			if (block && (prev_state & TASK_UNINTERRUPTIBLE)
  6858				&& trace_sched_blocked_reason_enabled()) {
  6859				unsigned long blocked_func = 0;
  6860	
> 6861				stack_trace_save_tsk(prev, &blocked_func, 1, 0);
  6862				trace_sched_blocked_reason(prev, (void *)blocked_func);
  6863			}
  6864	
  6865			/* Also unlocks the rq: */
  6866			rq = context_switch(rq, prev, next, &rf);
  6867		} else {
  6868			rq_unpin_lock(rq, &rf);
  6869			__balance_callbacks(rq);
  6870			raw_spin_rq_unlock_irq(rq);
  6871		}
  6872	}
  6873	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki