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From:   Benjamin Tissoires <benjamin.tissoires@redhat.com>
To:     Greg KH <gregkh@linuxfoundation.org>,
        Jiri Kosina <jikos@kernel.org>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>,
        Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@kernel.org>, Shuah Khan <shuah@kernel.org>,
        Dave Marchevsky <davemarchevsky@fb.com>,
        Joe Stringer <joe@cilium.io>
Cc:     Tero Kristo <tero.kristo@linux.intel.com>,
        linux-kernel@vger.kernel.org, linux-input@vger.kernel.org,
        netdev@vger.kernel.org, bpf@vger.kernel.org,
        linux-kselftest@vger.kernel.org,
        Benjamin Tissoires <benjamin.tissoires@redhat.com>
Subject: [PATCH bpf-next v2 24/28] HID: bpf: only call hid_bpf_raw_event() if a ctx is available
Date:   Fri,  4 Mar 2022 18:28:48 +0100
Message-Id: <20220304172852.274126-25-benjamin.tissoires@redhat.com>
In-Reply-To: <20220304172852.274126-1-benjamin.tissoires@redhat.com>
References: <20220304172852.274126-1-benjamin.tissoires@redhat.com>
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the context is allocated the first time a program of type DEVICE_EVENT
is attached to the device. To not add too much jumps in the code for
the general device handling, call hid_bpf_raw_event() only if we know
that a program has been attached once during the life of the device.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>

---

new in v2
---
 drivers/hid/hid-core.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index d0e015986e17..2b49f6064a40 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -1751,10 +1751,13 @@ int hid_report_raw_event(struct hid_device *hid, int type, u8 *data, u32 size,
 	u8 *cdata;
 	int ret = 0;
 
-	data = hid_bpf_raw_event(hid, data, &size);
-	if (IS_ERR(data)) {
-		ret = PTR_ERR(data);
-		goto out;
+	/* we pre-test if ctx is available here to cut the calls at the earliest */
+	if (hid->bpf.ctx) {
+		data = hid_bpf_raw_event(hid, data, &size);
+		if (IS_ERR(data)) {
+			ret = PTR_ERR(data);
+			goto out;
+		}
 	}
 
 	report = hid_get_report(report_enum, data);
-- 
2.35.1