On Thu, Oct 29, 2020 at 3:10 PM Ian Rogers <irogers@xxxxxxxxxx> wrote: > > If bits is 0, the case when the map is empty, then the >> is the size of > the register which is undefined behavior - on x86 it is the same as a > shift by 0. > Avoid calling hash_bits with bits == 0 by adding additional empty > hashmap tests. > > Suggested-by: Andrii Nakryiko <andriin@xxxxxx>, > Suggested-by: Song Liu <songliubraving@xxxxxx> > Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx> > --- I didn't realize you'd need to add three extra checks. If that's the case, let's just add `if (!bits) return 0;` to hash_bits() and be done with it. Please keep hashmap__for_each_key_entry_safe/hashmap__for_each_key_entry changes, they are ok regardless. > tools/lib/bpf/hashmap.c | 12 ++++++++++-- > tools/lib/bpf/hashmap.h | 12 ++++++------ > 2 files changed, 16 insertions(+), 8 deletions(-) > [...]
