Re: [PATCH 1/3] kthread: add a mechanism to store cgroup info
From: Tejun Heo <tj@kernel.org>
Date: 2017-09-08 14:35:44
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Hello, On Wed, Sep 06, 2017 at 07:00:51PM -0700, Shaohua Li wrote:
+#ifdef CONFIG_CGROUPS +void kthread_set_orig_css(struct cgroup_subsys_state *css); +struct cgroup_subsys_state *kthread_get_orig_css(void); +void kthread_reset_orig_css(void);
* It's a bit weird to associate a kthread with a css without being specific. If what's needed is a generic association (this kthread is temporarily servicing this cgroup), it should be associated with the cgroup. But, I think it'd be better to make it specific instead - ie. kthread_set_io_css(). * Do we need the reset function to be separate? Can't we just clear it when the set function is called with NULL css? * For the accessor, can we do sth like kthread_orig_css() (or kthread_io_css())? "get" is overloaded between set/get and get/put, so it can get confusing.
quoted hunk ↗ jump to hunk
diff --git a/include/linux/sched.h b/include/linux/sched.h index c05ac5f..ab2295d 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h@@ -1276,6 +1276,7 @@ extern struct pid *cad_pid; #define PF_SWAPWRITE 0x00800000 /* Allowed to write to swap */ #define PF_NO_SETAFFINITY 0x04000000 /* Userland is not allowed to meddle with cpus_allowed */ #define PF_MCE_EARLY 0x08000000 /* Early kill for mce process policy */ +#define PF_KTHREAD_HAS_CSS 0x10000000 /* kthread has css info attached */
Do we need a separate flag for this? kthreads already have PF_KTHREAD set. I'm not sure why we'd need another flag. Once we know it's a kthread, we can just access its css pointer field, right? Thanks. -- tejun