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 buffered and 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 file operations to avoid the buffering. The resctrlfs.c defines functions that interact with the resctrl FS while resctrl_val.c defines functions that perform measurements on the cache. Run_benchmark() fits logically into the second file before resctrl_val() that uses it. Move run_benchmark() from resctrlfs.c to resctrl_val.c and remove redundant part of the kernel-doc comment. Make run_benchmark() static and remove it from the header file. Patch series is based on [1] which is based on [2] which are based on kselftest next branch. Changelog v6: - Align schema_len error checking with typical snprintf format. (Reinette) - Initialize schema string for early return eventuality. (Reinette) Changelog v5: - Add Ilpo's reviewed-by tag to Patch 1/2. - Reword patch messages slightly. - Add error check to schema_len variable. Changelog v4: - Change git signature from Wieczor-Retman Maciej to Maciej Wieczor-Retman. - Rebase onto [1] which is based on [2]. (Reinette) - Add fcntl.h explicitly to provide glibc backward compatibility. (Reinette) Changelog v3: - Use snprintf() return value instead of strlen() in write_schemata(). (Ilpo) - Make run_benchmark() static and remove it from the header file. (Reinette) - Add Ilpo's reviewed-by tag to Patch 2/2. - Patch messages and cover letter rewording. 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/ [v2] https://lore.kernel.org/all/cover.1693213468.git.maciej.wieczor-retman@xxxxxxxxx/ [v3] https://lore.kernel.org/all/cover.1693575451.git.maciej.wieczor-retman@xxxxxxxxx/ [v4] https://lore.kernel.org/all/cover.1695369120.git.maciej.wieczor-retman@xxxxxxxxx/ [v5] https://lore.kernel.org/all/cover.1695975327.git.maciej.wieczor-retman@xxxxxxxxx/ [1] https://lore.kernel.org/all/20231002094813.6633-1-ilpo.jarvinen@xxxxxxxxxxxxxxx/ [2] https://lore.kernel.org/all/20230904095339.11321-1-ilpo.jarvinen@xxxxxxxxxxxxxxx/ Maciej Wieczor-Retman (2): selftests/resctrl: Fix schemata write error check selftests/resctrl: Move run_benchmark() to a more fitting file tools/testing/selftests/resctrl/resctrl.h | 1 - tools/testing/selftests/resctrl/resctrl_val.c | 50 +++++++++++ tools/testing/selftests/resctrl/resctrlfs.c | 88 +++++-------------- 3 files changed, 73 insertions(+), 66 deletions(-) -- 2.42.0
