On 03/05/2019 11:47 PM, Javier Honduvilla Coto wrote: > Hi all, > > This patch add the bpf_progenyof helper which receives a PID and returns > 1 if the process currently being executed is in the process hierarchy, > including itself or 0 if not. > > This is very useful in tracing programs when we want to filter by a > given PID and all the children it might have. The current workarounds > most people implement for this purpose have issues: > > - Attaching to process spawning syscalls and dynamically add those PIDs > to some bpf map that would be used to filter is cumbersome and > potentially racy. > - Unrolling some loop to perform what this helper is doing consumes lots > of instructions. That and the impossibility to jump backwards makes it > really hard to be correct in really large process chains. > > Let me know what do you think! > > Thanks, > > --- > Changed in V3: > - Removed RCU read (un)locking as BPF programs alredy run in RCU > locked > context > - progenyof(0) now returns 1, which, semantically makes more sense > - Added new test case for PID 0 and changed sentinel value for errors > - Rebase on latest bpf-next/master > - Used my work email as somehow I accidentally used my personal one > in v2 > > Changed in V2: > - Adding missing docs in include/uapi/linux/bpf.h > > Javier Honduvilla Coto (3): > bpf: add bpf_progenyof helper > bpf: sync kernel uapi headers > bpf: add tests for bpf_progenyof > > include/linux/bpf.h | 1 + > include/uapi/linux/bpf.h | 10 +- > kernel/bpf/core.c | 1 + > kernel/bpf/helpers.c | 32 +++ > kernel/trace/bpf_trace.c | 2 + > tools/include/uapi/linux/bpf.h | 9 +- > tools/testing/selftests/bpf/.gitignore | 1 + > tools/testing/selftests/bpf/Makefile | 2 +- > tools/testing/selftests/bpf/bpf_helpers.h | 1 + > .../selftests/bpf/progs/test_progenyof_kern.c | 46 +++ > .../selftests/bpf/test_progenyof_user.c | 268 ++++++++++++++++++ > 11 files changed, 370 insertions(+), 3 deletions(-) > create mode 100644 tools/testing/selftests/bpf/progs/test_progenyof_kern.c > create mode 100644 tools/testing/selftests/bpf/test_progenyof_user.c >
bpf-next is closed right now due to merge window, please resubmit once it opens, thanks!
