linux-kernel - [PATCH 2/2] HID: wiimote: narrow spinlock range in wiimote_hid

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Date:   Fri,  4 Sep 2020 14:21:43 +0100
From:   Ian Abbott <abbotti@....co.uk>
To:     linux-input@...r.kernel.org
Cc:     David Rheinsberg <david.rheinsberg@...il.com>,
        Jiri Kosina <jikos@...nel.org>,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        Ian Abbott <abbotti@....co.uk>, linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] HID: wiimote: narrow spinlock range in wiimote_hid_event()

In `wiimote_hid_event()`, the `wdata->state.lock` spinlock does not need
to be held while searching `handlers[]` for a suitable handler function.
Change it so the spinlock is only held during the call to the handler
function itself.

Signed-off-by: Ian Abbott <abbotti@....co.uk>
---
 drivers/hid/hid-wiimote-core.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/hid/hid-wiimote-core.c b/drivers/hid/hid-wiimote-core.c
index e03a0ba5611a..41012681cafd 100644
--- a/drivers/hid/hid-wiimote-core.c
+++ b/drivers/hid/hid-wiimote-core.c
@@ -1625,12 +1625,12 @@ static int wiimote_hid_event(struct hid_device *hdev, struct hid_report *report,
 	if (size < 1)
 		return -EINVAL;
 
-	spin_lock_irqsave(&wdata->state.lock, flags);
-
 	for (i = 0; handlers[i].id; ++i) {
 		h = &handlers[i];
 		if (h->id == raw_data[0] && h->size < size) {
+			spin_lock_irqsave(&wdata->state.lock, flags);
 			h->func(wdata, &raw_data[1]);
+			spin_unlock_irqrestore(&wdata->state.lock, flags);
 			break;
 		}
 	}
@@ -1639,8 +1639,6 @@ static int wiimote_hid_event(struct hid_device *hdev, struct hid_report *report,
 		hid_warn(hdev, "Unhandled report %hhu size %d\n", raw_data[0],
 									size);
 
-	spin_unlock_irqrestore(&wdata->state.lock, flags);
-
 	return 0;
 }
 
-- 
2.28.0