[android-common:android14-6.1 6542/6550] arch/arm64/kvm/hyp/nvhe/trace.c:150:56: warning: variable 'new_head' set but not used

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

tree:   https://android.googlesource.com/kernel/common android14-6.1
head:   b5a5282ca964178e46d1adb96ea1c3341303e94b
commit: 4c095252cfa95e2d7850c70ec055de1b2284cc76 [6542/6550] ANDROID: KVM: arm64: Add tracing support for the nVHE hyp
config: arm64-allyesconfig (https://download.01.org/0day-ci/archive/20230128/202301282336.MwZEUQuS-lkp@intel.com/config)
compiler: aarch64-linux-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        git remote add android-common https://android.googlesource.com/kernel/common
        git fetch --no-tags android-common android14-6.1
        git checkout 4c095252cfa95e2d7850c70ec055de1b2284cc76
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=arm64 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=arm64 SHELL=/bin/bash arch/arm64/kvm/

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

   arch/arm64/kvm/hyp/nvhe/trace.c: In function 'rb_move_tail':
>> arch/arm64/kvm/hyp/nvhe/trace.c:150:56: warning: variable 'new_head' set but not used [-Wunused-but-set-variable]
     150 |         struct hyp_buffer_page *tail_page, *new_tail, *new_head;
         |                                                        ^~~~~~~~
   arch/arm64/kvm/hyp/nvhe/trace.c: At top level:
>> arch/arm64/kvm/hyp/nvhe/trace.c:190:15: warning: no previous prototype for 'rb_event_size' [-Wmissing-prototypes]
     190 | unsigned long rb_event_size(unsigned long length)
         |               ^~~~~~~~~~~~~


vim +/new_head +150 arch/arm64/kvm/hyp/nvhe/trace.c

   146	
   147	static struct hyp_buffer_page *
   148	rb_move_tail(struct hyp_rb_per_cpu *cpu_buffer)
   149	{
 > 150		struct hyp_buffer_page *tail_page, *new_tail, *new_head;
   151	
   152		tail_page = cpu_buffer->tail_page;
   153		new_tail = rb_next_page(tail_page);
   154	again:
   155		/*
   156		 * We caught the reader ... Let's try to move the head page.
   157		 * The writer can only rely on ->next links to check if this is head.
   158		 */
   159		if ((unsigned long)tail_page->list.next & HYP_RB_PAGE_HEAD) {
   160			/* The reader moved the head in between */
   161			if (!rb_set_flag(tail_page, HYP_RB_PAGE_UPDATE))
   162				goto again;
   163	
   164			atomic_add(atomic_read(&new_tail->entries), &cpu_buffer->overrun);
   165	
   166			/* Move the head */
   167			rb_set_flag(new_tail, HYP_RB_PAGE_HEAD);
   168	
   169			/* The new head is in place, reset the update flag */
   170			rb_set_flag(tail_page, 0);
   171	
   172			new_head = rb_next_page(new_tail);
   173		}
   174	
   175		rb_footer_writer_status(tail_page, 0);
   176		rb_footer_writer_status(new_tail, RB_PAGE_FT_COMMIT);
   177	
   178		local_set(&new_tail->page->commit, 0);
   179	
   180		atomic_set(&new_tail->write, 0);
   181		atomic_set(&new_tail->entries, 0);
   182	
   183		atomic_inc(&cpu_buffer->pages_touched);
   184	
   185		cpu_buffer->tail_page = new_tail;
   186	
   187		return new_tail;
   188	}
   189	
 > 190	unsigned long rb_event_size(unsigned long length)
   191	{
   192		struct ring_buffer_event *event;
   193	
   194		return length + RB_EVNT_HDR_SIZE + sizeof(event->array[0]);
   195	}
   196	

-- 
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https://github.com/intel/lkp-tests