Re: [PATCH] perf/bpf: Fix lockless access to parent_event->prog in perf_event_alloc()

Hi Deepanshu,

kernel test robot noticed the following build errors:

[auto build test ERROR on perf-tools-next/perf-tools-next]
[also build test ERROR on tip/perf/core perf-tools/perf-tools linus/master v7.2 next-20260821]
[cannot apply to acme/perf/core]
[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/Deepanshu-Kartikey/perf-bpf-Fix-lockless-access-to-parent_event-prog-in-perf_event_alloc/20260821-071210
base:   https://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git perf-tools-next
patch link:    https://lore.kernel.org/r/20260821014210.18681-1-kartikey406%40gmail.com
patch subject: [PATCH] perf/bpf: Fix lockless access to parent_event->prog in perf_event_alloc()
config: arm-randconfig-004-20260825 (https://download.01.org/0day-ci/archive/20260825/[email protected]/config)
compiler: arm-linux-gnueabi-gcc (GCC) 13.4.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260825/[email protected]/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 <[email protected]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/

All errors (new ones prefixed by >>):

   arm-linux-gnueabi-ld: kernel/events/core.o: in function `__list_add':
>> include/linux/list.h:159:(.text.perf_event_alloc.part.0+0x96c): undefined reference to `bpf_event_mutex'
   arm-linux-gnueabi-ld: drivers/pci/controller/cadence/pcie-cadence-plat.o: in function `cdns_plat_pcie_probe':
   drivers/pci/controller/cadence/pcie-cadence-plat.c:85:(.text.cdns_plat_pcie_probe+0xfc): undefined reference to `cdns_pcie_host_setup'


vim +159 include/linux/list.h

d7c816733d501b5 Kees Cook        2016-08-17  147  
^1da177e4c3f415 Linus Torvalds   2005-04-16  148  /*
^1da177e4c3f415 Linus Torvalds   2005-04-16  149   * Insert a new entry between two known consecutive entries.
^1da177e4c3f415 Linus Torvalds   2005-04-16  150   *
^1da177e4c3f415 Linus Torvalds   2005-04-16  151   * This is only for internal list manipulation where we know
^1da177e4c3f415 Linus Torvalds   2005-04-16  152   * the prev/next entries already!
^1da177e4c3f415 Linus Torvalds   2005-04-16  153   */
^1da177e4c3f415 Linus Torvalds   2005-04-16  154  static inline void __list_add(struct list_head *new,
^1da177e4c3f415 Linus Torvalds   2005-04-16  155  			      struct list_head *prev,
^1da177e4c3f415 Linus Torvalds   2005-04-16  156  			      struct list_head *next)
^1da177e4c3f415 Linus Torvalds   2005-04-16  157  {
d7c816733d501b5 Kees Cook        2016-08-17  158  	if (!__list_add_valid(new, prev, next))
d7c816733d501b5 Kees Cook        2016-08-17 @159  		return;
d7c816733d501b5 Kees Cook        2016-08-17  160  
^1da177e4c3f415 Linus Torvalds   2005-04-16  161  	next->prev = new;
^1da177e4c3f415 Linus Torvalds   2005-04-16  162  	new->next = next;
^1da177e4c3f415 Linus Torvalds   2005-04-16  163  	new->prev = prev;
1c97be677f72b3c Paul E. McKenney 2015-09-20  164  	WRITE_ONCE(prev->next, new);
^1da177e4c3f415 Linus Torvalds   2005-04-16  165  }
^1da177e4c3f415 Linus Torvalds   2005-04-16  166  

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