linux-kernel - [PATCH 2/2] drm/amdkfd: Slighly optimize 'init_doorbell

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Message-Id: <3e54737649cf94daabaa5b51db9f4c21d43124fe.1637516393.git.christophe.jaillet@wanadoo.fr>
Date:   Sun, 21 Nov 2021 18:41:40 +0100
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Felix.Kuehling@....com, alexander.deucher@....com,
        christian.koenig@....com, Xinhui.Pan@....com, airlied@...ux.ie,
        daniel@...ll.ch
Cc:     amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>
Subject: [PATCH 2/2] drm/amdkfd: Slighly optimize 'init_doorbell_bitmap()'

The 'doorbell_bitmap' bitmap has just been allocated. So we can use the
non-atomic '__set_bit()' function to save a few cycles as no concurrent
access can happen.

Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
---
bitmap_set() could certainly also be use, but range checking would be
tricky.
---
 drivers/gpu/drm/amd/amdkfd/kfd_process.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
index 172ee8763523..2e9d341062c4 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
@@ -1447,9 +1447,9 @@ static int init_doorbell_bitmap(struct qcm_process_device *qpd,
 
 	for (i = 0; i < KFD_MAX_NUM_OF_QUEUES_PER_PROCESS / 2; i++) {
 		if (i >= range_start && i <= range_end) {
-			set_bit(i, qpd->doorbell_bitmap);
-			set_bit(i + KFD_QUEUE_DOORBELL_MIRROR_OFFSET,
-				qpd->doorbell_bitmap);
+			__set_bit(i, qpd->doorbell_bitmap);
+			__set_bit(i + KFD_QUEUE_DOORBELL_MIRROR_OFFSET,
+				  qpd->doorbell_bitmap);
 		}
 	}
 
-- 
2.30.2