Hi Steven,

kernel test robot noticed the following build warnings:

https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    
https://github.com/intel-lab-lkp/linux/commits/Steven-Rostedt/tracing-Remove-dummy-options-and-flags/20251106-010511
base:   https://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace 
for-next
patch link:    https://lore.kernel.org/r/20251105161935.545400234%40kernel.org
patch subject: [PATCH 3/5] tracing: Have tracer option be instance specific
config: i386-randconfig-r072-20251107 
(https://download.01.org/0day-ci/archive/20251107/[email protected]/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 
87f0227cb60147a26a1eeb4fb06e3b505e9c7261)

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]>
| Reported-by: Dan Carpenter <[email protected]>
| Closes: https://lore.kernel.org/r/[email protected]/

smatch warnings:
kernel/trace/trace.c:6313 tracing_set_tracer() warn: iterator used outside 
loop: 't'

vim +/t +6313 kernel/trace/trace.c

9c5b9d3d65e4858 Masami Hiramatsu         2020-01-11  6285  int 
tracing_set_tracer(struct trace_array *tr, const char *buf)
09d23a1d8a82e81 Steven Rostedt (Red Hat  2015-02-03  6286) {
4699bbb369ba1d3 Steven Rostedt           2025-11-05  6287       struct tracer 
*trace;
4699bbb369ba1d3 Steven Rostedt           2025-11-05  6288       struct tracers 
*t;
12883efb670c28d Steven Rostedt (Red Hat  2013-03-05  6289) #ifdef 
CONFIG_TRACER_MAX_TRACE
34600f0e9c33c9c Steven Rostedt           2013-01-22  6290       bool had_max_tr;
12883efb670c28d Steven Rostedt (Red Hat  2013-03-05  6291) #endif
d33b10c0c73adca Steven Rostedt           2024-12-24  6292       int ret;
bc0c38d139ec7fc Steven Rostedt           2008-05-12  6293  
d33b10c0c73adca Steven Rostedt           2024-12-24  6294       
guard(mutex)(&trace_types_lock);
1027fcb206a0fb8 Steven Rostedt           2009-03-12  6295  
7a1d1e4b9639ff0 Steven Rostedt (Google   2024-06-12  6296)      
update_last_data(tr);
7a1d1e4b9639ff0 Steven Rostedt (Google   2024-06-12  6297) 
a1f157c7a3bb342 Zheng Yejian             2023-09-06  6298       if 
(!tr->ring_buffer_expanded) {
2b6080f28c7cc3e Steven Rostedt           2012-05-11  6299               ret = 
__tracing_resize_ring_buffer(tr, trace_buf_size,
438ced1720b5840 Vaibhav Nagarnaik        2012-02-02  6300                       
                        RING_BUFFER_ALL_CPUS);
73c5162aa362a54 Steven Rostedt           2009-03-11  6301               if (ret 
< 0)
d33b10c0c73adca Steven Rostedt           2024-12-24  6302                       
return ret;
73c5162aa362a54 Steven Rostedt           2009-03-11  6303               ret = 0;
73c5162aa362a54 Steven Rostedt           2009-03-11  6304       }
73c5162aa362a54 Steven Rostedt           2009-03-11  6305  
4699bbb369ba1d3 Steven Rostedt           2025-11-05  6306       
list_for_each_entry(t, &tr->tracers, list) {
4699bbb369ba1d3 Steven Rostedt           2025-11-05  6307               if 
(strcmp(t->tracer->name, buf) == 0)
bc0c38d139ec7fc Steven Rostedt           2008-05-12  6308                       
break;
bc0c38d139ec7fc Steven Rostedt           2008-05-12  6309       }
d33b10c0c73adca Steven Rostedt           2024-12-24  6310       if (!t)

t can't be NULL here.  It needs to be if (list_entry_is_head()) return;

d33b10c0c73adca Steven Rostedt           2024-12-24  6311               return 
-EINVAL;
d33b10c0c73adca Steven Rostedt           2024-12-24  6312  
4699bbb369ba1d3 Steven Rostedt           2025-11-05 @6313       if (t->tracer 
== tr->current_trace)
d33b10c0c73adca Steven Rostedt           2024-12-24  6314               return 
0;
bc0c38d139ec7fc Steven Rostedt           2008-05-12  6315  
4699bbb369ba1d3 Steven Rostedt           2025-11-05  6316       trace = 
t->tracer;
4699bbb369ba1d3 Steven Rostedt           2025-11-05  6317  

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki


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