Write_schemata() uses fprintf() to write a bitmask into a schemata file inside resctrl FS. It checks fprintf() return value but it doesn't check fclose() return value. Error codes from fprintf() such as write errors, are flushed back to the user only after fclose() is executed which means any invalid bitmask can be written into the schemata file. Rewrite write_schemata() to use syscalls instead of stdio functions to interact with the schemata file. Change sprintf() to snprintf() in write_schemata(). In case of write() returning an error pass the string acquired with strerror() to the "reason" buffer. Extend "reason" buffer by a factor of two so it can hold longer error messages. The resctrlfs.c file defines functions that interact with the resctrl FS while resctrl_val.c file defines functions that perform measurements on the cache. Run_benchmark() fits logically into the second file before resctrl_val() function that uses it. Move run_benchmark() from resctrlfs.c to resctrl_val.c just before resctrl_val() function definition. Series is based on kselftest next branch. Changelog v2: - Change sprintf() to snprintf() in write_schemata(). - Redo write_schemata() with syscalls instead of stdio functions. - Fix typos and missing dots in patch messages. - Branch printf attribute patch to a separate series. [v1] https://lore.kernel.org/all/cover.1692880423.git.maciej.wieczor-retman@xxxxxxxxx/ Wieczor-Retman, Maciej (2): selftests/resctrl: Fix schemata write error check selftests/resctrl: Move run_benchmark() to a more fitting file tools/testing/selftests/resctrl/resctrl_val.c | 50 ++++++++++++ tools/testing/selftests/resctrl/resctrlfs.c | 76 ++++--------------- 2 files changed, 63 insertions(+), 63 deletions(-) base-commit: 13eb52f6293dbda02890698d92f3d9913d8d5aeb -- 2.42.0
