From 6cb6d437b57a16487197e4abc3ab2838d7bf473c Mon Sep 17 00:00:00 2001 From: Xiaogang Chen Date: Mon, 28 Oct 2024 15:06:19 -0500 Subject: [PATCH] drm/amdkfd: change kfd process kref count at creation kfd process kref count(process->ref) is initialized to 1 by kref_init. After it is created not need to increase its kref. Instad add kfd process kref at kfd process mmu notifier allocation since we already decrease the kref at free_notifier of mmu_notifier_ops, so pair them. When user process opens kfd node multiple times the kfd process kref is increased each time to balance with kfd node close operation. Signed-off-by: Xiaogang Chen Reviewed-by: Felix Kuehling Signed-off-by: Alex Deucher --- drivers/gpu/drm/amd/amdkfd/kfd_process.c | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-) diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c b/drivers/gpu/drm/amd/amdkfd/kfd_process.c index ff34bb1ac9db..87cd52cf4ee9 100644 --- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c +++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c @@ -854,8 +854,10 @@ struct kfd_process *kfd_create_process(struct task_struct *thread) goto out; } - /* A prior open of /dev/kfd could have already created the process. */ - process = find_process(thread, false); + /* A prior open of /dev/kfd could have already created the process. + * find_process will increase process kref in this case + */ + process = find_process(thread, true); if (process) { pr_debug("Process already found\n"); } else { @@ -903,8 +905,6 @@ 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); @@ -1190,10 +1190,8 @@ static void kfd_process_ref_release(struct kref *ref) static struct mmu_notifier *kfd_process_alloc_notifier(struct mm_struct *mm) { - int idx = srcu_read_lock(&kfd_processes_srcu); - struct kfd_process *p = find_process_by_mm(mm); - - srcu_read_unlock(&kfd_processes_srcu, idx); + /* This increments p->ref counter if kfd process p exists */ + struct kfd_process *p = kfd_lookup_process_by_mm(mm); return p ? &p->mmu_notifier : ERR_PTR(-ESRCH); } -- 2.20.1