linux-kernel - [PATCH 2/2] drm/amdkfd: Use non-atomic bitmap functions when possible

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Message-Id: <d18382516544c0a8c0b8e563087cb6a8b2893078.1638117878.git.christophe.jaillet@wanadoo.fr>
Date:   Sun, 28 Nov 2021 17:46:15 +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: Use non-atomic bitmap functions when possible

All uses of the 'kfd->gtt_sa_bitmap' bitmap are protected with the
'kfd->gtt_sa_lock' mutex.

So:
   - prefer the non-atomic '__set_bit()' function
   - use the non-atomic 'bitmap_[set|clear]()' functions instead of
     equivalent 'for' loops. These functions can work on several bits at a
     time

Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
---
 drivers/gpu/drm/amd/amdkfd/kfd_device.c | 16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_device.c b/drivers/gpu/drm/amd/amdkfd/kfd_device.c
index c5a0ce44a295..c4d868a5dd97 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_device.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_device.c
@@ -1346,7 +1346,7 @@ int kfd_gtt_sa_allocate(struct kfd_dev *kfd, unsigned int size,
 	/* If we need only one chunk, mark it as allocated and get out */
 	if (size <= kfd->gtt_sa_chunk_size) {
 		pr_debug("Single bit\n");
-		set_bit(found, kfd->gtt_sa_bitmap);
+		__set_bit(found, kfd->gtt_sa_bitmap);
 		goto kfd_gtt_out;
 	}
 
@@ -1384,10 +1384,8 @@ int kfd_gtt_sa_allocate(struct kfd_dev *kfd, unsigned int size,
 		(*mem_obj)->range_start, (*mem_obj)->range_end);
 
 	/* Mark the chunks as allocated */
-	for (found = (*mem_obj)->range_start;
-		found <= (*mem_obj)->range_end;
-		found++)
-		set_bit(found, kfd->gtt_sa_bitmap);
+	bitmap_set(kfd->gtt_sa_bitmap, (*mem_obj)->range_start,
+		   (*mem_obj)->range_end - (*mem_obj)->range_start + 1);
 
 kfd_gtt_out:
 	mutex_unlock(&kfd->gtt_sa_lock);
@@ -1402,8 +1400,6 @@ int kfd_gtt_sa_allocate(struct kfd_dev *kfd, unsigned int size,
 
 int kfd_gtt_sa_free(struct kfd_dev *kfd, struct kfd_mem_obj *mem_obj)
 {
-	unsigned int bit;
-
 	/* Act like kfree when trying to free a NULL object */
 	if (!mem_obj)
 		return 0;
@@ -1414,10 +1410,8 @@ int kfd_gtt_sa_free(struct kfd_dev *kfd, struct kfd_mem_obj *mem_obj)
 	mutex_lock(&kfd->gtt_sa_lock);
 
 	/* Mark the chunks as free */
-	for (bit = mem_obj->range_start;
-		bit <= mem_obj->range_end;
-		bit++)
-		clear_bit(bit, kfd->gtt_sa_bitmap);
+	bitmap_clear(kfd->gtt_sa_bitmap, mem_obj->range_start,
+		     mem_obj->range_end - mem_obj->range_start + 1);
 
 	mutex_unlock(&kfd->gtt_sa_lock);
 
-- 
2.30.2