From d6f9bbce18762116698c40cc7de836a9d0c9f832 Mon Sep 17 00:00:00 2001
From: Xiang Liu <xiang.liu@amd.com>
Date: Thu, 13 Mar 2025 11:24:55 +0800
Subject: [PATCH] drm/amdgpu: Fix computation for remain size of CPER ring
The mistake of computation for remain size of CPER ring will cause
unbreakable while cycle when CPER ring overflow.
Signed-off-by: Xiang Liu <xiang.liu@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_cper.c | 15 ++++++++-------
1 file changed, 8 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cper.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_cper.c
index 3f291b30b79f6..360e07a5c7c1f 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cper.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cper.c
@@ -455,10 +455,10 @@ static u32 amdgpu_cper_ring_get_ent_sz(struct amdgpu_ring *ring, u64 pos)
return umin(rec_len, chunk);
}
-void amdgpu_cper_ring_write(struct amdgpu_ring *ring,
- void *src, int count)
+void amdgpu_cper_ring_write(struct amdgpu_ring *ring, void *src, int count)
{
u64 pos, wptr_old, rptr = *ring->rptr_cpu_addr & ring->ptr_mask;
+ int rec_cnt_dw = count >> 2;
u32 chunk, ent_sz;
u8 *s = (u8 *)src;
@@ -485,6 +485,9 @@ void amdgpu_cper_ring_write(struct amdgpu_ring *ring,
s += chunk;
}
+ if (ring->count_dw < rec_cnt_dw)
+ ring->count_dw = 0;
+
/* the buffer is overflow, adjust rptr */
if (((wptr_old < rptr) && (rptr <= ring->wptr)) ||
((ring->wptr < wptr_old) && (wptr_old < rptr)) ||
@@ -501,12 +504,10 @@ void amdgpu_cper_ring_write(struct amdgpu_ring *ring,
pos = rptr;
} while (!amdgpu_cper_is_hdr(ring, rptr));
}
- mutex_unlock(&ring->adev->cper.ring_lock);
- if (ring->count_dw >= (count >> 2))
- ring->count_dw -= (count >> 2);
- else
- ring->count_dw = 0;
+ if (ring->count_dw >= rec_cnt_dw)
+ ring->count_dw -= rec_cnt_dw;
+ mutex_unlock(&ring->adev->cper.ring_lock);
}
static u64 amdgpu_cper_ring_get_rptr(struct amdgpu_ring *ring)
--
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