Re: [PATCH 4/4] tracing: Allow boot instances to have snapshot buffers

Hi Steven,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on akpm-mm/mm-everything]
[also build test WARNING on linus/master v6.2-rc3 next-20230111]
[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/Steven-Rostedt/tracing-Add-creation-of-instances-at-boot-command-line/20230111-230425
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link:    https://lore.kernel.org/r/20230111145842.847715402%40goodmis.org
patch subject: [PATCH 4/4] tracing: Allow boot instances to have snapshot buffers
config: i386-randconfig-s001
compiler: gcc-11 (Debian 11.3.0-8) 11.3.0
reproduce:
        # apt-get install sparse
        # sparse version: v0.6.4-39-gce1a6720-dirty
        # https://github.com/intel-lab-lkp/linux/commit/b4515aa1407184147348b74b42bf10af90b905e7
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Steven-Rostedt/tracing-Add-creation-of-instances-at-boot-command-line/20230111-230425
        git checkout b4515aa1407184147348b74b42bf10af90b905e7
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' O=build_dir ARCH=i386 olddefconfig
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' O=build_dir ARCH=i386 SHELL=/bin/bash kernel/trace/

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot [off-list ref]

sparse warnings: (new ones prefixed by >>)
   kernel/trace/trace.c:5809:1: sparse: sparse: trying to concatenate 11905-character string (8191 bytes max)
   kernel/trace/trace.c:444:28: sparse: sparse: incorrect type in argument 1 (different address spaces) @@     expected struct trace_export **list @@     got struct trace_export [noderef] __rcu ** @@
   kernel/trace/trace.c:444:28: sparse:     expected struct trace_export **list
   kernel/trace/trace.c:444:28: sparse:     got struct trace_export [noderef] __rcu **
   kernel/trace/trace.c:458:33: sparse: sparse: incorrect type in argument 1 (different address spaces) @@     expected struct trace_export **list @@     got struct trace_export [noderef] __rcu ** @@
   kernel/trace/trace.c:458:33: sparse:     expected struct trace_export **list
   kernel/trace/trace.c:458:33: sparse:     got struct trace_export [noderef] __rcu **
   kernel/trace/trace.c:2934:38: sparse: sparse: incorrect type in argument 1 (different address spaces) @@     expected struct event_filter *filter @@     got struct event_filter [noderef] __rcu *filter @@
   kernel/trace/trace.c:2934:38: sparse:     expected struct event_filter *filter
   kernel/trace/trace.c:2934:38: sparse:     got struct event_filter [noderef] __rcu *filter

quoted

kernel/trace/trace.c:10208:51: sparse: sparse: Using plain integer as NULL pointer

   kernel/trace/trace.c:398:9: sparse: sparse: incompatible types in comparison expression (different address spaces):
   kernel/trace/trace.c:398:9: sparse:    struct trace_export [noderef] __rcu *
   kernel/trace/trace.c:398:9: sparse:    struct trace_export *
   kernel/trace/trace.c:413:9: sparse: sparse: incompatible types in comparison expression (different address spaces):
   kernel/trace/trace.c:413:9: sparse:    struct trace_export [noderef] __rcu *
   kernel/trace/trace.c:413:9: sparse:    struct trace_export *

vim +10208 kernel/trace/trace.c

 10188	
 10189	#ifdef CONFIG_TRACER_MAX_TRACE
 10190	__init static bool tr_needs_alloc_snapshot(const char *name)
 10191	{
 10192		char *test;
 10193		int len = strlen(name);
 10194		bool ret;
 10195	
 10196		if (!boot_snapshot_index)
 10197			return false;
 10198	
 10199		if (strncmp(name, boot_snapshot_info, len) == 0 &&
 10200		    boot_snapshot_info[len] == '\t')
 10201			return true;
 10202	
 10203		test = kmalloc(strlen(name) + 3, GFP_KERNEL);
 10204		if (!test)
 10205			return false;
 10206	
 10207		sprintf(test, "\t%s\t", name);
 10208		ret = strstr(boot_snapshot_info, test) == 0;
 10209		kfree(test);
 10210		return ret;
 10211	}
 10212	

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