From b90ca8badbd11488e5f762346b028666808164e7 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Fri, 30 Jul 2021 12:24:33 +0100 Subject: sched: Introduce task_struct::user_cpus_ptr to track requested affinity In preparation for saving and restoring the user-requested CPU affinity mask of a task, add a new cpumask_t pointer to 'struct task_struct'. If the pointer is non-NULL, then the mask is copied across fork() and freed on task exit. Signed-off-by: Will Deacon Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Valentin Schneider Link: https://lore.kernel.org/r/20210730112443.23245-7-will@kernel.org --- kernel/fork.c | 2 ++ kernel/sched/core.c | 20 ++++++++++++++++++++ 2 files changed, 22 insertions(+) (limited to 'kernel') diff --git a/kernel/fork.c b/kernel/fork.c index 1a9af73b47c1..5d7addf0c41a 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -446,6 +446,7 @@ void put_task_stack(struct task_struct *tsk) void free_task(struct task_struct *tsk) { + release_user_cpus_ptr(tsk); scs_release(tsk); #ifndef CONFIG_THREAD_INFO_IN_TASK @@ -919,6 +920,7 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node) #endif if (orig->cpus_ptr == &orig->cpus_mask) tsk->cpus_ptr = &tsk->cpus_mask; + dup_user_cpus_ptr(tsk, orig, node); /* * One for the user space visible state that goes away when reaped. diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 8cec0d24c88c..360a3ec6d03b 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2480,6 +2480,26 @@ void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask) __do_set_cpus_allowed(p, new_mask, 0); } +int dup_user_cpus_ptr(struct task_struct *dst, struct task_struct *src, + int node) +{ + if (!src->user_cpus_ptr) + return 0; + + dst->user_cpus_ptr = kmalloc_node(cpumask_size(), GFP_KERNEL, node); + if (!dst->user_cpus_ptr) + return -ENOMEM; + + cpumask_copy(dst->user_cpus_ptr, src->user_cpus_ptr); + return 0; +} + +void release_user_cpus_ptr(struct task_struct *p) +{ + kfree(p->user_cpus_ptr); + p->user_cpus_ptr = NULL; +} + /* * This function is wildly self concurrent; here be dragons. * -- cgit v1.2.3