On 2024-10-09 14:08, Xiaogang.Chen wrote:
From: Xiaogang Chen <[email protected]>
kfd process kref count(process->ref) is initialized to 1 by kref_init. After
it is created not need to increaes its kref. Instad add kfd process kref at kfd
process mmu notifier allocation since we decrease the ref at free_notifier of
mmu_notifier_ops, so pair them.
That's not correct. kfd_create_process returns a struct kfd_process *
reference. That gets stored by the caller in filep->private_data. That
requires incrementing the reference count. You can have multiple
references to the same struct kfd_process if user mode opens /dev/kfd
multiple times. The reference is released in kfd_release. Your change
breaks that use case.
The reference released in kfd_process_free_notifier is only one per
process and it's the reference created by kref_init.
Regards,
Felix
Signed-off-by: Xiaogang Chen <[email protected]>
---
drivers/gpu/drm/amd/amdkfd/kfd_process.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
index d07acf1b2f93..7c5471d7d743 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
@@ -899,8 +899,6 @@ struct kfd_process *kfd_create_process(struct task_struct
*thread)
init_waitqueue_head(&process->wait_irq_drain);
}
out:
- if (!IS_ERR(process))
- kref_get(&process->ref);
mutex_unlock(&kfd_processes_mutex);
mmput(thread->mm);
@@ -1191,7 +1189,11 @@ static struct mmu_notifier *kfd_process_alloc_notifier(struct mm_struct *mm)
srcu_read_unlock(&kfd_processes_srcu, idx);
- return p ? &p->mmu_notifier : ERR_PTR(-ESRCH);
+ if (p) {
+ kref_get(&p->ref);
+ return &p->mmu_notifier;
+ }
+ return ERR_PTR(-ESRCH);
}
static void kfd_process_free_notifier(struct mmu_notifier *mn)
