Am 10.04.2017 um 09:26 schrieb Liu, Monk:
That is unnecessary the "if (seq + amdgpu_sched_jobs < cring->sequence) {" will
catch this case.
But what if user land pass in seq 0 on purpose , but the latest cring->sequence
value is only 3 ?
Without this "if (seq == 0)" the logic seems goes to a wrong direction
If cring->sequence is only 3 cring->fences[0] will be NULL, so we will
just return NULL anyway (We might want to add a comment explaining that).
Christian.
BR Monk
-----邮件原件-----
发件人: Christian König [mailto:[email protected]]
发送时间: Monday, April 10, 2017 3:22 PM
收件人: Liu, Monk <[email protected]>; [email protected]
主题: Re: [PATCH] drm/amdgpu:fix race condition
Am 10.04.2017 um 09:18 schrieb Monk Liu:
sequence is protected by spinlock so don't access sequence in paramter
seq when invoking this function.
~0 means to get the latest sequence number and 0 means none to get.
Change-Id: Ib7a03f3cf5594deeb4ad333cc59b47a6bddfd1ad
Signed-off-by: Monk Liu <[email protected]>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
index 6d86eae..71d5f25 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
@@ -277,6 +277,13 @@ struct fence *amdgpu_ctx_get_fence(struct
amdgpu_ctx *ctx,
spin_lock(&ctx->ring_lock);
+ if (seq == ~0) {
That must be ~0ull, otherwise you would be checking a 32bit value here.
Additional to that please define something in amdgpu_drm.h for that value.
+ seq = ctx->rings[ring->idx].sequence - 1;
+ } else if(seq == 0) {
+ spin_unlock(&ctx->ring_lock);
+ return NULL;
+ }
+
That is unnecessary the "if (seq + amdgpu_sched_jobs < cring->sequence) {" will
catch this case.
Regards,
Christian.
if (seq >= cring->sequence) {
spin_unlock(&ctx->ring_lock);
return ERR_PTR(-EINVAL);
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