Re: [PATCH v2 bpf 2/3] ftrace: bpf: Fix IPMODIFY + DIRECT in modify_ftrace_direct()

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

Hi Song,

kernel test robot noticed the following build errors:

[auto build test ERROR on bpf/master]

url:    https://github.com/intel-lab-lkp/linux/commits/Song-Liu/ftrace-Fix-BPF-fexit-with-livepatch/20251025-023411
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git master
patch link:    https://lore.kernel.org/r/20251024182901.3247573-3-song%40kernel.org
patch subject: [PATCH v2 bpf 2/3] ftrace: bpf: Fix IPMODIFY + DIRECT in modify_ftrace_direct()
config: sparc-randconfig-r132-20251026 (https://download.01.org/0day-ci/archive/20251026/202510261733.fSN9P6td-lkp@intel.com/config)
compiler: sparc64-linux-gcc (GCC) 8.5.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251026/202510261733.fSN9P6td-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/202510261733.fSN9P6td-lkp@intel.com/

All errors (new ones prefixed by >>):

   kernel/bpf/trampoline.c: In function 'register_fentry':
>> kernel/bpf/trampoline.c:229:11: error: dereferencing pointer to incomplete type 'struct ftrace_ops'
      tr->fops->trampoline = 0;
              ^~


vim +229 kernel/bpf/trampoline.c

   207	
   208	/* first time registering */
   209	static int register_fentry(struct bpf_trampoline *tr, void *new_addr)
   210	{
   211		void *ip = tr->func.addr;
   212		unsigned long faddr;
   213		int ret;
   214	
   215		faddr = ftrace_location((unsigned long)ip);
   216		if (faddr) {
   217			if (!tr->fops)
   218				return -ENOTSUPP;
   219			tr->func.ftrace_managed = true;
   220		}
   221	
   222		if (tr->func.ftrace_managed) {
   223			ftrace_set_filter_ip(tr->fops, (unsigned long)ip, 0, 1);
   224			/*
   225			 * Clearing fops->trampoline and fops->NULL is
   226			 * needed by the "goto again" case in
   227			 * bpf_trampoline_update().
   228			 */
 > 229			tr->fops->trampoline = 0;
   230			tr->fops->func = NULL;
   231			ret = register_ftrace_direct(tr->fops, (long)new_addr);
   232		} else {
   233			ret = bpf_arch_text_poke(ip, BPF_MOD_CALL, NULL, new_addr);
   234		}
   235	
   236		return ret;
   237	}
   238	

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