From: Tejun Heo <tj@kernel.org> mainline inclusion from mainline-v6.12-rc1 commit 1bbcfe620e03aafc542b1c649dea0a9499a4490f category: feature bugzilla: https://atomgit.com/openeuler/kernel/issues/8335 Reference: https://web.git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commi... -------------------------------- check_hotplug_seq() is used to detect CPU hotplug event which occurred while the BPF scheduler is being loaded so that initialization can be retried if CPU hotplug events take place before the CPU hotplug callbacks are online. As such, the best place to call it is in the same cpu_read_lock() section that enables the CPU hotplug ops. Currently, it is called in the next cpus_read_lock() block in scx_ops_enable(). The side effect of this placement is a small window in which hotplug sequence detection can trigger unnecessarily, which isn't critical. Move check_hotplug_seq() invocation to the same cpus_read_lock() block as the hotplug operation enablement to close the window and get the invocation out of the way for planned locking updates. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: David Vernet <void@manifault.com> Signed-off-by: Zicheng Qu <quzicheng@huawei.com> Signed-off-by: cheliequan <cheliequan@inspur.com> Signed-off-by: Luo Gengkun <luogengkun2@huawei.com> --- kernel/sched/ext.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index 790a6f6db130..0f42f9e03d1f 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -5058,6 +5058,7 @@ static int scx_ops_enable(struct sched_ext_ops *ops) if (((void (**)(void))ops)[i]) static_branch_enable_cpuslocked(&scx_has_op[i]); + check_hotplug_seq(ops); cpus_read_unlock(); ret = validate_ops(ops); @@ -5106,8 +5107,6 @@ static int scx_ops_enable(struct sched_ext_ops *ops) cpus_read_lock(); scx_cgroup_lock(); - check_hotplug_seq(ops); - for (i = SCX_OPI_NORMAL_BEGIN; i < SCX_OPI_NORMAL_END; i++) if (((void (**)(void))ops)[i]) static_branch_enable_cpuslocked(&scx_has_op[i]); -- 2.34.1