Re: [PATCH 3/4] bpf: runtime part of fast-path termination approach

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

Hi Siddharth,

kernel test robot noticed the following build errors:

[auto build test ERROR on bpf-next/net]
[also build test ERROR on bpf-next/master bpf/master linus/master v6.17-rc5 next-20250905]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Siddharth-Chintamaneni/bpf-Introduce-new-structs-and-struct-fields-for-fast-path-termination/20250908-070655
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git net
patch link:    https://lore.kernel.org/r/20250907230415.289327-4-sidchintamaneni%40gmail.com
patch subject: [PATCH 3/4] bpf: runtime part of fast-path termination approach
config: sh-randconfig-001-20250908 (https://download.01.org/0day-ci/archive/20250908/202509081431.PcY1azAC-lkp@intel.com/config)
compiler: sh4-linux-gcc (GCC) 14.3.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250908/202509081431.PcY1azAC-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/202509081431.PcY1azAC-lkp@intel.com/

All errors (new ones prefixed by >>):

   kernel/watchdog.c: In function 'is_softlockup':
>> kernel/watchdog.c:709:25: error: implicit declaration of function 'bpf_softlockup'; did you mean 'is_softlockup'? [-Wimplicit-function-declaration]
     709 |                         bpf_softlockup(now - touch_ts);
         |                         ^~~~~~~~~~~~~~
         |                         is_softlockup


vim +709 kernel/watchdog.c

   678	
   679	static int is_softlockup(unsigned long touch_ts,
   680				 unsigned long period_ts,
   681				 unsigned long now)
   682	{
   683		if ((watchdog_enabled & WATCHDOG_SOFTOCKUP_ENABLED) && watchdog_thresh) {
   684			/*
   685			 * If period_ts has not been updated during a sample_period, then
   686			 * in the subsequent few sample_periods, period_ts might also not
   687			 * be updated, which could indicate a potential softlockup. In
   688			 * this case, if we suspect the cause of the potential softlockup
   689			 * might be interrupt storm, then we need to count the interrupts
   690			 * to find which interrupt is storming.
   691			 */
   692			if (time_after_eq(now, period_ts + get_softlockup_thresh() / NUM_SAMPLE_PERIODS) &&
   693			    need_counting_irqs())
   694				start_counting_irqs();
   695	
   696			/*
   697			 * A poorly behaving BPF scheduler can live-lock the system into
   698			 * soft lockups. Tell sched_ext to try ejecting the BPF
   699			 * scheduler when close to a soft lockup.
   700			 */
   701			if (time_after_eq(now, period_ts + get_softlockup_thresh() * 3 / 4))
   702				scx_softlockup(now - touch_ts);
   703	
   704			/*
   705			 * Long running BPF programs can cause CPU's to stall.
   706			 * So trigger fast path termination to terminate such BPF programs.
   707			 */
   708			if (time_after_eq(now, period_ts + get_softlockup_thresh() * 3 / 4))
 > 709				bpf_softlockup(now - touch_ts);
   710	
   711			/* Warn about unreasonable delays. */
   712			if (time_after(now, period_ts + get_softlockup_thresh()))
   713				return now - touch_ts;
   714		}
   715		return 0;
   716	}
   717	

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