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authorQiu Peiyang <peiyangx.qiu@intel.com>2015-12-25 14:46:00 +0800
committerSteven Rostedt <rostedt@goodmis.org>2016-01-07 15:56:21 -0500
commit5156dca34a3e1e1edac2d0dabf43d8632909b7aa (patch)
tree9b75d4ecfe3d1d1b20d73f21baab2bf0b0969b70 /include/linux/tracepoint.h
parentb7ffffbb46f205e7727a18bcc7a46c3c2b534f7c (diff)
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ftrace: Fix the race between ftrace and insmod
We hit ftrace_bug report when booting Android on a 64bit ATOM SOC chip. Basically, there is a race between insmod and ftrace_run_update_code. After load_module=>ftrace_module_init, another thread jumps in to call ftrace_run_update_code=>ftrace_arch_code_modify_prepare =>set_all_modules_text_rw, to change all modules as RW. Since the new module is at MODULE_STATE_UNFORMED, the text attribute is not changed. Then, the 2nd thread goes ahead to change codes. However, load_module continues to call complete_formation=>set_section_ro_nx, then 2nd thread would fail when probing the module's TEXT. The patch fixes it by using notifier to delay the enabling of ftrace records to the time when module is at state MODULE_STATE_COMING. Link: http://lkml.kernel.org/r/567CE628.3000609@intel.com Signed-off-by: Qiu Peiyang <peiyangx.qiu@intel.com> Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'include/linux/tracepoint.h')
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