Changes since v7: ================ - v7 can be seen here: https://lore.kernel.org/all/20250811064609.918593-1-bhup...@igalia.com/ - As suggested by Andy used '--base' option with git-format to indicate the version of 'linux-next/master' this patchset is rebased on. Also used the 'Link' tag in the commit log. - Also added a new [PATCH 5/5] to replace BUILD_BUG_ON() with static_assert() inside 'set_task_comm()'.
Changes since v6: ================ - v6 can be seen here: https://lore.kernel.org/all/20250724123612.206110-1-bhup...@igalia.com/ - As suggested by Linus, we got rid of 'get_task_comm()' entirely and replaced it with 'strscpy_pad()' implementation. - Also changed the current memcpy() use-cases which use 'current->comm' to copy the task name over to local copies, to call a wrappper like "get_task_array()". - Collected 'Reviewed-by' from Kees for [PATCH 1/4]. Changes since v5: ================ - v5 can be seen here: https://lore.kernel.org/lkml/20250716123916.511889-1-bhup...@igalia.com/ - As suggested by Linus, replaced 'tsk->comm' with 'tsk->comm_str' locally, and verified basic thread names and then changed 'tsk->comm_str' back to 'tsk->comm'. So essentially now 'tsk->comm' is TASK_COMM_EXT_LEN i.e. 64-bytes long. Changes since v4: ================ - v4 can be seen here: https://lore.kernel.org/lkml/20250521062337.53262-1-bhup...@igalia.com/ - As suggested by Kees, replaced tsk->comm with tsk->comm_str, inside 'task_struct' where TASK_COMM_EXT_LEN is 64-bytes. Changes since v3: ================ - v3 can be seen here: https://lore.kernel.org/lkml/20250507110444.963779-1-bhup...@igalia.com/ - As suggested by Petr and Steven, used 'comm_ext' name instead of 'real_comm'. Correspondingly the macro name is changed to 'TASK_COMM_EXT_LEN' for the 64-byte extended comm. - Rebased this patchset on linux-next/master, which contain the following patch from Steven now: 155fd6c3e2f0 ("tracing/sched: Use __string() instead of fixed lengths for task->comm") - Accordingly, v4 drops the changes done for 'trace/sched' events in v3, but retains the 'safe' memcpy' changes for other kernel trace users. Changes since v2: ================ - v2 can be seen here: https://lore.kernel.org/lkml/20250331121820.455916-1-bhup...@igalia.com/ - As suggested by Yafang and Kees, picked Linus' suggested approach for this version (see: <https://lore.kernel.org/all/CAHk-=wjAmmHUg6vho1KjzQi2=psr30+cogfd4axrthr2gsi...@mail.gmail.com/>). - Dropped kthreads patch from this version. It would be sent out separately, if we have a consensus on this approach. Changes since v1: ================ - v1 can be seen here: https://lore.kernel.org/lkml/20250314052715.610377-1-bhup...@igalia.com/ - As suggested by Kees, added [PATCH 3/3] to have a consistent 'full_name' entry inside 'task_struct' which both tasks and kthreads can use. - Fixed the commit message to indicate that the existing ABI '/proc/$pid/task/$tid/comm' remains untouched and a parallel '/proc/$pid/task/$tid/full_name' ABI for new (interested) users. While working with user-space debugging tools which work especially on linux gaming platforms, I found that the task name is truncated due to the limitation of TASK_COMM_LEN. Now, during debug tracing, seeing truncated names is not very useful, especially on gaming platforms where the number of tasks running can be very high. This patchset does not touch 'TASK_COMM_LEN' at all, i.e. 'TASK_COMM_LEN' and the 16-byte design remains untouched. Via this patchset, Linus suggested 'tsk->comm' is made 64-byte long and equal to TASK_COMM_EXT_LEN. To avoid any surprises / bug,s I replaced 'tsk->comm' with 'tsk->comm_str' locally inside 'task_struct' and checked compilation of code and basic working of thread names: struct task_struct { .............. char comm_str[TASK_COMM_EXT_LEN]; .............. }; where TASK_COMM_EXT_LEN is 64-bytes. Once done, I changed the name back to 'tsk->comm'. To ensure that the existing ABI and userspace continues to work as intended, we ensure that: - Existing users of 'get_task_comm'/ 'set_task_comm' will get 'tsk->comm' truncated to a maximum of 'TASK_COMM_LEN' (16-bytes) to maintain ABI, - New / Modified users of 'get_task_comm'/ 'set_task_comm' will get 'tsk->comm' supported up to a maximum of 'TASK_COMM_EXT_LEN' (64-bytes). Note, that the existing users have not been modified to migrate to 'TASK_COMM_EXT_LEN', in case they have hard-coded expectations of dealing with only a 'TASK_COMM_LEN' long 'tsk->comm_str'. After this change, gdb is able to show full name of the task, using a simple app which generates threads with long names [see 1]: # gdb ./threadnames -ex "run info thread" -ex "detach" -ex "quit" > log # cat log NameThatIsTooLongForComm[4662] [1]. https://github.com/lostgoat/tasknames Bhupesh (5): exec: Remove obsolete comments include: Set tsk->comm length to 64 bytes treewide: Replace 'get_task_comm()' with 'strscpy_pad()' treewide: Switch memcpy() users of 'task->comm' to a more safer implementation include: Replace BUILD_BUG_ON with static_assert in 'set_task_comm()' drivers/connector/cn_proc.c | 2 +- drivers/dma-buf/sw_sync.c | 2 +- .../gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c | 2 +- .../drm/amd/amdgpu/amdgpu_eviction_fence.c | 2 +- drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c | 2 +- .../gpu/drm/amd/amdgpu/amdgpu_userq_fence.c | 2 +- drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 4 +- drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c | 2 +- drivers/gpu/drm/lima/lima_ctx.c | 2 +- drivers/gpu/drm/panfrost/panfrost_gem.c | 2 +- drivers/gpu/drm/panthor/panthor_gem.c | 2 +- drivers/gpu/drm/virtio/virtgpu_ioctl.c | 2 +- drivers/hwtracing/stm/core.c | 2 +- drivers/tty/tty_audit.c | 2 +- fs/bcachefs/thread_with_file.c | 2 +- fs/binfmt_elf.c | 2 +- fs/binfmt_elf_fdpic.c | 2 +- fs/ocfs2/cluster/netdebug.c | 1 - fs/proc/array.c | 2 +- include/linux/coredump.h | 2 +- include/linux/sched.h | 51 ++++++++++++------- include/linux/tracepoint.h | 4 +- include/trace/events/block.h | 10 ++-- include/trace/events/oom.h | 2 +- include/trace/events/osnoise.h | 2 +- include/trace/events/sched.h | 13 +++-- include/trace/events/signal.h | 2 +- include/trace/events/task.h | 4 +- kernel/audit.c | 6 ++- kernel/auditsc.c | 6 ++- kernel/sys.c | 2 +- mm/kmemleak.c | 6 --- net/bluetooth/hci_sock.c | 2 +- net/netfilter/nf_tables_api.c | 2 +- security/integrity/integrity_audit.c | 3 +- security/ipe/audit.c | 2 +- security/landlock/domain.c | 2 +- security/lsm_audit.c | 7 +-- tools/bpf/bpftool/pids.c | 6 +-- .../bpf/test_kmods/bpf_testmod-events.h | 2 +- 40 files changed, 92 insertions(+), 83 deletions(-) base-commit: 5303936d609e09665deda94eaedf26a0e5c3a087 -- 2.38.1
