Hi Yonghong,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on bpf-next/master]
url:
https://github.com/0day-ci/linux/commits/Yonghong-Song/bpf-add-bpf_get_stack-helper/20180418-210810
base: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
Currently, stackmap and bpf_get_stackid helper are provided
for bpf program to get the stack trace. This approach has
a limitation though. If two stack traces have the same hash,
only one will get stored in the stackmap table,
so some stack traces are missing from user perspective.
This patch
