On Wed, Jan 24, 2018 at 8:42 PM, Alexei Starovoitov <alexei.starovoi...@gmail.com> wrote: > On Wed, Jan 24, 2018 at 08:37:52PM -0800, Joel Fernandes wrote: >> Currently stackmaps can't be iterated over. The keys are obtained >> through other maps and look ups have to be performed. In new usecases, >> its useful to be able to iterate over the stackmap independently. >> Implement bpf_get_next_key to make this possible. >> >> More details of use case: >> Currently iterating over stack maps is done like so, for example >> in BCC tools offcputime script: >> 1. Obtain keys from the 'counts' hash map. >> 2. Look up stackmap with each of the keys obtained from step 1. >> >> This makes the iteration of stackmap dependent on the counts map. >> In a new tool I'm working on called BPFd [1], it gives a huge speed >> up when I dump entire maps before transmitting them to BCC tools >> on a different machine [2]. This patch makes it possible to dump >> stackmaps independent of other maps. >> >> Tested on x86 and arm64 machines. >> >> [1] https://lwn.net/Articles/744522/ >> [2] https://github.com/joelagnel/bpfd/issues/8 >> >> Cc: Alexei Starovoitov <a...@kernel.org> >> Cc: Daniel Borkmann <dan...@iogearbox.net> >> Cc: Brendan Gregg <bgr...@netflix.com> >> Cc: Brenden Blanco <bbla...@gmail.com> >> Signed-off-by: Joel Fernandes <joe...@google.com> >> --- >> kernel/bpf/stackmap.c | 18 +++++++++++++++++- >> 1 file changed, 17 insertions(+), 1 deletion(-) >> >> diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c >> index a15bc636cc98..b0bf7d009f76 100644 >> --- a/kernel/bpf/stackmap.c >> +++ b/kernel/bpf/stackmap.c >> @@ -228,7 +228,23 @@ int bpf_stackmap_copy(struct bpf_map *map, void *key, >> void *value) >> >> static int stack_map_get_next_key(struct bpf_map *map, void *key, void >> *next_key) >> { >> - return -EINVAL; >> + struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, >> map); >> + u32 id = 0; > > did you check net-next tree before sending the patch?
Oh. I was a bit late to send it! Glad its done though. > Also please see Documentation/bpf/bpf_devel_QA.txt Sure, if you don't mind could you elaborate what I screwed up from the QA with regard to this patch? Sorry if I missed something. thanks, - Joel
