On 2/27/24 12:45 PM, Eduard Zingerman wrote:
Make bpf_map__set_autocreate() for struct_ops maps toggle autoload
state for referenced programs.
E.g. for the BPF code below:
SEC("struct_ops/test_1") int BPF_PROG(foo) { ... }
SEC("struct_ops/test_2") int BPF_PROG(bar) { ... }
SEC(".struct_ops.link")
struct test_ops___v1 A = {
.foo = (void *)foo
};
SEC(".struct_ops.link")
struct test_ops___v2 B = {
.foo = (void *)foo,
.bar = (void *)bar,
};
And the following libbpf API calls:
bpf_map__set_autocreate(skel->maps.A, true);
bpf_map__set_autocreate(skel->maps.B, false);
The autoload would be enabled for program 'foo' and disabled for
program 'bar'.
Do not apply such toggling if program autoload state is set by a call
to bpf_program__set_autoload().
Signed-off-by: Eduard Zingerman <eddyz87@xxxxxxxxx>
---
tools/lib/bpf/libbpf.c | 35 ++++++++++++++++++++++++++++++++++-
1 file changed, 34 insertions(+), 1 deletion(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index b39d3f2898a1..1ea3046724f8 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -446,13 +446,18 @@ struct bpf_program {
struct bpf_object *obj;
int fd;
- bool autoload;
+ bool autoload:1;
+ bool autoload_user_set:1;
bool autoattach;
bool sym_global;
bool mark_btf_static;
enum bpf_prog_type type;
enum bpf_attach_type expected_attach_type;
int exception_cb_idx;
+ /* total number of struct_ops maps with autocreate == true
+ * that reference this program
+ */
+ __u32 struct_ops_refs;
Instead of adding struct_ops_refs and autoload_user_set,
for BPF_PROG_TYPE_STRUCT_OPS, how about deciding to load it or not by checking
prog->attach_btf_id (non zero) alone. The prog->attach_btf_id is now decided at
load time and is only set if it is used by at least one autocreate map, if I
read patch 2 & 3 correctly.
Meaning ignore prog->autoload*. Load the struct_ops prog as long as it is used
by one struct_ops map with autocreate == true.
If the struct_ops prog is not used in any struct_ops map, the bpf prog cannot be
loaded even the autoload is set. If bpf prog is used in a struct_ops map and its
autoload is set to false, the struct_ops map will be in broken state. Thus,
prog->autoload does not fit very well with struct_ops prog and may as well
depend on whether the struct_ops prog is used by a struct_ops map alone?
