Now that BPF supports adding new kernel functions with kfuncs, and storing kernel objects in maps with kptrs, we can add a set of kfuncs which allow struct task_struct objects to be stored in maps as referenced kptrs. The possible use-cases for doing this are plentiful. During tracing, for example, it would be useful to be able to collect some tasks that performed a certain operation, and then periodically summarize who they are, which cgroup they're in, how much CPU time they've spent, etc. Doing this now would require storing the task's pids along with some relevant data to be exported to user space, and later associating the pids to tasks in other event handlers where the data is recorded. Another useful by-product of this is that it allows a program to pin a task, and by proxy therefore also pin its task local storage. This patch set adds this aforementioned set of kfuncs, along with a new selftest suite for validation. David Vernet (2): bpf: Add kfuncs for storing struct task_struct * as a kptr bpf/selftests: Add selftests for new task kfuncs kernel/bpf/helpers.c | 75 ++++++++- .../selftests/bpf/prog_tests/task_kfunc.c | 152 ++++++++++++++++++ .../selftests/bpf/progs/task_kfunc_common.h | 82 ++++++++++ .../selftests/bpf/progs/task_kfunc_failure.c | 132 +++++++++++++++ .../selftests/bpf/progs/task_kfunc_success.c | 111 +++++++++++++ 5 files changed, 551 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/bpf/prog_tests/task_kfunc.c create mode 100644 tools/testing/selftests/bpf/progs/task_kfunc_common.h create mode 100644 tools/testing/selftests/bpf/progs/task_kfunc_failure.c create mode 100644 tools/testing/selftests/bpf/progs/task_kfunc_success.c -- 2.37.3
