On 8/20/19 11:52 AM, Quentin Monnet wrote:
Implement the show_fdinfo hook for BTF FDs file operations, and make it
print the id and the size of the BTF object. This allows for a quick
retrieval of the BTF id from its FD; or it can help understanding what
type of object (BTF) the file descriptor points to.
Signed-off-by: Quentin Monnet <quentin.monnet@xxxxxxxxxxxxx>
Reviewed-by: Jakub Kicinski <jakub.kicinski@xxxxxxxxxxxxx>
---
kernel/bpf/btf.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 5fcc7a17eb5a..39e184f1b27c 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -3376,6 +3376,19 @@ void btf_type_seq_show(const struct btf *btf, u32 type_id, void *obj,
btf_type_ops(t)->seq_show(btf, t, type_id, obj, 0, m);
}
+#ifdef CONFIG_PROC_FS
+static void bpf_btf_show_fdinfo(struct seq_file *m, struct file *filp)
+{
+ const struct btf *btf = filp->private_data;
+
+ seq_printf(m,
+ "btf_id:\t%u\n"
+ "data_size:\t%u\n",
+ btf->id,
+ btf->data_size);
Looks good, exposing btf_id makes sense to me in order to correlate with applications.
Do you have a concrete use case for data_size to expose it this way as opposed to fetch
it via btf_get_info_by_fd()? If not, I'd say lets only add btf_id in there.
+}
+#endif
+
static int btf_release(struct inode *inode, struct file *filp)
{
btf_put(filp->private_data);
@@ -3383,6 +3396,9 @@ static int btf_release(struct inode *inode, struct file *filp)
}
const struct file_operations btf_fops = {
+#ifdef CONFIG_PROC_FS
+ .show_fdinfo = bpf_btf_show_fdinfo,
+#endif
.release = btf_release,
};
Thanks,
Daniel
