kernel/trace/ring_buffer.c:412:29-47: WARNING: casting value returned by memory allocation function to (struct buffer_page *) is useless.

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

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   8ba098e6b6ff0db8edf28528d1552be261af30d4
commit: b1e7a590a0133606d3efd41aee38cdeac630b52f ring-buffer: Add helper functions for allocations
date:   8 months ago
config: openrisc-randconfig-r062-20260801 (https://download.01.org/0day-ci/archive/20260801/202608010824.vc7vATf0-lkp@intel.com/config)
compiler: or1k-linux-gcc (GCC) 9.5.0

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
| Fixes: b1e7a590a013 ("ring-buffer: Add helper functions for allocations")
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202608010824.vc7vATf0-lkp@intel.com/

cocci warnings: (new ones prefixed by >>)
>> kernel/trace/ring_buffer.c:412:29-47: WARNING: casting value returned by memory allocation function to (struct buffer_page *) is useless.
>> kernel/trace/ring_buffer.c:408:31-57: WARNING: casting value returned by memory allocation function to (struct ring_buffer_per_cpu *) is useless.

vim +412 kernel/trace/ring_buffer.c

   403	
   404	/*
   405	 * For best performance, allocate cpu buffer data cache line sized
   406	 * and per CPU.
   407	 */
 > 408	#define alloc_cpu_buffer(cpu) (struct ring_buffer_per_cpu *)		\
   409		kzalloc_node(ALIGN(sizeof(struct ring_buffer_per_cpu),		\
   410				   cache_line_size()), GFP_KERNEL, cpu_to_node(cpu));
   411	
 > 412	#define alloc_cpu_page(cpu) (struct buffer_page *)			\
   413		kzalloc_node(ALIGN(sizeof(struct buffer_page),			\
   414				   cache_line_size()), GFP_KERNEL, cpu_to_node(cpu));
   415	

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