Alexei Starovoitov 8c290e60fa bpf: fix hashmap extra_elems logic ... In both kmalloc and prealloc mode the bpf_map_update_elem() is using per-cpu extra_elems to do atomic update when the map is full. There are two issues with it. The logic can be misused, since it allows max_entries+num_cpus elements to be present in the map. And alloc_extra_elems() at map creation time can fail percpu alloc for large map values with a warn: WARNING: CPU: 3 PID: 2752 at ../mm/percpu.c:892 pcpu_alloc+0x119/0xa60 illegal size (32824) or align (8) for percpu allocation The fixes for both of these issues are different for kmalloc and prealloc modes. For prealloc mode allocate extra num_possible_cpus elements and store their pointers into extra_elems array instead of actual elements. Hence we can use these hidden(spare) elements not only when the map is full but during bpf_map_update_elem() that replaces existing element too. That also improves performance, since pcpu_freelist_pop/push is avoided. Unfortunately this approach cannot be used for kmalloc mode which needs to kfree elements after rcu grace period. Therefore switch it back to normal kmalloc even when full and old element exists like it was prior to commit 6c90598174 ("bpf: pre-allocate hash map elements"). Add tests to check for over max_entries and large map values. Reported-by: Dave Jones <davej@codemonkey.org.uk> Fixes: 6c90598174 ("bpf: pre-allocate hash map elements") Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>		2017-03-22 14:12:18 -07:00
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.gitignore	bpf: Add test_tag to .gitignore	2017-02-10 15:56:08 -05:00
bpf_util.h	bpf: fix multiple issues in selftest suite and samples	2016-11-27 20:38:47 -05:00
config	bpf: add initial suite for selftests	2016-10-18 11:35:55 -04:00
Makefile	selftests/bpf: fix broken build, take 2	2017-03-21 18:57:58 -07:00
test_kmod.sh	selftests: do not require bash to run bpf tests	2017-01-05 13:19:47 -07:00
test_lpm_map.c	bpf: Remove bpf_sys.h from selftests	2017-02-10 15:56:08 -05:00
test_lru_map.c	bpf: Remove bpf_sys.h from selftests	2017-02-10 15:56:08 -05:00
test_maps.c	bpf: fix hashmap extra_elems logic	2017-03-22 14:12:18 -07:00
test_tag.c	bpf: Remove bpf_sys.h from selftests	2017-02-10 15:56:08 -05:00
test_verifier.c	selftests/bpf: fix broken build	2017-03-12 23:48:41 -07:00