Re: [RFC PATCH v0.1 4/9] sched/umcg: implement core UMCG API
flat view
From: Andrei Vagin <hidden>
Date: 2021-05-21 19:09:12
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On Thu, May 20, 2021 at 11:36:09AM -0700, Peter Oskolkov wrote:
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@@ -67,7 +137,75 @@ SYSCALL_DEFINE4(umcg_register_task, u32, api_version, u32, flags, u32, group_id, */ SYSCALL_DEFINE1(umcg_unregister_task, u32, flags) { - return -ENOSYS; + struct umcg_task_data *utd; + int ret = -EINVAL; + + rcu_read_lock(); + utd = rcu_dereference(current->umcg_task_data); + + if (!utd || flags) + goto out; + + task_lock(current); + rcu_assign_pointer(current->umcg_task_data, NULL); + task_unlock(current); + + ret = 0; + +out: + rcu_read_unlock(); + if (!ret && utd) { + synchronize_rcu();
synchronize_rcu is expensive. Do we really need to call it here? Can we use kfree_rcu? Where is task->umcg_task_data freed when a task is destroyed?
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+ kfree(utd); + } + return ret; +} +