netdev - [PATCH HID for-next v1 9/9] HID: bpf: reorder BPF registration

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Date:   Fri,  6 Jan 2023 11:23:32 +0100
From:   Benjamin Tissoires <benjamin.tissoires@...hat.com>
To:     Greg KH <gregkh@...uxfoundation.org>,
        Jiri Kosina <jikos@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:     Tero Kristo <tero.kristo@...ux.intel.com>,
        linux-kernel@...r.kernel.org, linux-input@...r.kernel.org,
        netdev@...r.kernel.org, bpf@...r.kernel.org,
        linux-kselftest@...r.kernel.org,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>
Subject: [PATCH HID for-next v1 9/9] HID: bpf: reorder BPF registration

Given that our initial BPF program is not using any kfuncs anymore,
we can reorder the initialization to first try to load it and then
register the kfuncs. This has the advantage of not exporting kfuncs
when HID-BPF is not working.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@...hat.com>
---
 drivers/hid/bpf/hid_bpf_dispatch.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/hid/bpf/hid_bpf_dispatch.c b/drivers/hid/bpf/hid_bpf_dispatch.c
index 26117b4ec016..8a034a555d4c 100644
--- a/drivers/hid/bpf/hid_bpf_dispatch.c
+++ b/drivers/hid/bpf/hid_bpf_dispatch.c
@@ -514,15 +514,16 @@ static int __init hid_bpf_init(void)
 		return 0;
 	}
 
-	err = register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING, &hid_bpf_kfunc_set);
+	err = hid_bpf_preload_skel();
 	if (err) {
-		pr_warn("error while setting HID BPF tracing kfuncs: %d", err);
+		pr_warn("error while preloading HID BPF dispatcher: %d", err);
 		return 0;
 	}
 
-	err = hid_bpf_preload_skel();
+	/* register tracing kfuncs after we are sure we can load our preloaded bpf program */
+	err = register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING, &hid_bpf_kfunc_set);
 	if (err) {
-		pr_warn("error while preloading HID BPF dispatcher: %d", err);
+		pr_warn("error while setting HID BPF tracing kfuncs: %d", err);
 		return 0;
 	}
 
-- 
2.38.1