From: "Steven Rostedt (Google)" rostedt@goodmis.org
The kernel command line ftrace_boot_snapshot by itself is supposed to trigger a snapshot at the end of boot up of the main top level trace buffer. A ftrace_boot_snapshot=foo will do the same for an instance called foo that was created by trace_instance=foo,...
The logic was broken where if ftrace_boot_snapshot was by itself, it would trigger a snapshot for all instances that had tracing enabled, regardless if it asked for a snapshot or not.
When a snapshot is requested for a buffer, the buffer's tr->allocated_snapshot is set to true. Use that to know if a trace buffer wants a snapshot at boot up or not.
Since the top level buffer is part of the ftrace_trace_arrays list, there's no reason to treat it differently than the other buffers. Just iterate the list if ftrace_boot_snapshot was specified.
Cc: stable@vger.kernel.org Fixes: 9c1c251d670bc ("tracing: Allow boot instances to have snapshot buffers") Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org --- kernel/trace/trace.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index ed1d1093f5e9..8ae51f1dea8e 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -10395,16 +10395,15 @@ void __init ftrace_boot_snapshot(void) { struct trace_array *tr;
- if (snapshot_at_boot) { - tracing_snapshot(); - internal_trace_puts("** Boot snapshot taken **\n"); - } + if (!snapshot_at_boot) + return;
list_for_each_entry(tr, &ftrace_trace_arrays, list) { - if (tr == &global_trace) + if (!tr->allocated_snapshot) continue; - trace_array_puts(tr, "** Boot snapshot taken **\n"); + tracing_snapshot_instance(tr); + trace_array_puts(tr, "** Boot snapshot taken **\n"); } }
Hi Steven,
kernel test robot noticed the following build errors:
[auto build test ERROR on akpm-mm/mm-everything] [also build test ERROR on linus/master v6.3-rc5 next-20230404] [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-Have-t... base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything patch link: https://lore.kernel.org/r/20230404230308.501833715%40goodmis.org patch subject: [PATCH 2/2] tracing: Fix ftrace_boot_snapshot command line logic config: arc-buildonly-randconfig-r003-20230403 (https://download.01.org/0day-ci/archive/20230405/202304051001.dL3Fvaxd-lkp@i...) compiler: arceb-elf-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 # https://github.com/intel-lab-lkp/linux/commit/ac5e916ec8d65b5e0c13719694efd3... git remote add linux-review https://github.com/intel-lab-lkp/linux git fetch --no-tags linux-review Steven-Rostedt/tracing-Have-tracing_snapshot_instance_cond-write-errors-to-the-appropriate-instance/20230405-070406 git checkout ac5e916ec8d65b5e0c13719694efd3084105f416 # save the config file mkdir build_dir && cp config build_dir/.config COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=arc olddefconfig COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=arc SHELL=/bin/bash kernel/
If you fix the issue, kindly add following tag where applicable | Reported-by: kernel test robot lkp@intel.com | Link: https://lore.kernel.org/oe-kbuild-all/202304051001.dL3Fvaxd-lkp@intel.com/
All errors (new ones prefixed by >>):
kernel/trace/trace.c: In function 'ftrace_boot_snapshot':
kernel/trace/trace.c:10402:24: error: 'struct trace_array' has no member named 'allocated_snapshot'
10402 | if (!tr->allocated_snapshot) | ^~
vim +10402 kernel/trace/trace.c
10393 10394 void __init ftrace_boot_snapshot(void) 10395 { 10396 struct trace_array *tr; 10397 10398 if (!snapshot_at_boot) 10399 return; 10400 10401 list_for_each_entry(tr, &ftrace_trace_arrays, list) { 10402 if (!tr->allocated_snapshot) 10403 continue; 10404 10405 tracing_snapshot_instance(tr); 10406 trace_array_puts(tr, "** Boot snapshot taken **\n"); 10407 } 10408 } 10409
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kernel test robot -
Steven Rostedt