[android-common:android16-6.12 1/1] kernel/sched/core.c:7724:4: 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 android16-6.12
head:   5f63d051ce041cdea246873cd91d9d864f8322cf
commit: b24c1517d9cc137d7ad4d356cc68fd94680ab998 [1/1] ANDROID: Fix invalid caller output in trace_sched_blocked_reason
config: arm-lpc18xx_defconfig (https://download.01.org/0day-ci/archive/20250221/202502210535.2R8EYar0-lkp@intel.com/config)
compiler: clang version 19.1.3 (https://github.com/llvm/llvm-project ab51eccf88f5321e7c60591c5546b254b6afab99)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250221/202502210535.2R8EYar0-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/202502210535.2R8EYar0-lkp@intel.com/

All errors (new ones prefixed by >>):

>> kernel/sched/core.c:7724:4: error: call to undeclared function 'stack_trace_save_tsk'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
    7724 |                         stack_trace_save_tsk(prev, &blocked_func, 1, 0);
         |                         ^
   1 error generated.


vim +/stack_trace_save_tsk +7724 kernel/sched/core.c

  7676	
  7677		trace_android_rvh_schedule(prev, next, rq);
  7678		if (likely(prev != next)) {
  7679			rq->nr_switches++;
  7680			/*
  7681			 * RCU users of rcu_dereference(rq->curr) may not see
  7682			 * changes to task_struct made by pick_next_task().
  7683			 */
  7684			RCU_INIT_POINTER(rq->curr, next);
  7685	
  7686			if (!task_current_donor(rq, next))
  7687				proxy_tag_curr(rq, next);
  7688	
  7689			/*
  7690			 * The membarrier system call requires each architecture
  7691			 * to have a full memory barrier after updating
  7692			 * rq->curr, before returning to user-space.
  7693			 *
  7694			 * Here are the schemes providing that barrier on the
  7695			 * various architectures:
  7696			 * - mm ? switch_mm() : mmdrop() for x86, s390, sparc, PowerPC,
  7697			 *   RISC-V.  switch_mm() relies on membarrier_arch_switch_mm()
  7698			 *   on PowerPC and on RISC-V.
  7699			 * - finish_lock_switch() for weakly-ordered
  7700			 *   architectures where spin_unlock is a full barrier,
  7701			 * - switch_to() for arm64 (weakly-ordered, spin_unlock
  7702			 *   is a RELEASE barrier),
  7703			 *
  7704			 * The barrier matches a full barrier in the proximity of
  7705			 * the membarrier system call entry.
  7706			 *
  7707			 * On RISC-V, this barrier pairing is also needed for the
  7708			 * SYNC_CORE command when switching between processes, cf.
  7709			 * the inline comments in membarrier_arch_switch_mm().
  7710			 */
  7711			++*switch_count;
  7712	
  7713			migrate_disable_switch(rq, prev);
  7714			psi_account_irqtime(rq, prev, next);
  7715			psi_sched_switch(prev, next, !task_on_rq_queued(prev) ||
  7716						     prev->se.sched_delayed);
  7717	
  7718			trace_sched_switch(preempt, prev, next, prev_state);
  7719	
  7720			if (block && (prev_state & TASK_UNINTERRUPTIBLE)
  7721				&& trace_sched_blocked_reason_enabled()) {
  7722				unsigned long blocked_func = 0;
  7723	
> 7724				stack_trace_save_tsk(prev, &blocked_func, 1, 0);
  7725				trace_sched_blocked_reason(prev, (void *)blocked_func);
  7726			}
  7727	
  7728			/* Also unlocks the rq: */
  7729			rq = context_switch(rq, prev, next, &rf);
  7730		} else {
  7731			/* In case next was already curr but just got blocked_donor */
  7732			if (prev_not_proxied && next->blocked_donor)
  7733				proxy_tag_curr(rq, next);
  7734	
  7735			rq_unpin_lock(rq, &rf);
  7736			__balance_callbacks(rq);
  7737			raw_spin_rq_unlock_irq(rq);
  7738		}
  7739	}
  7740	

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