sched: fix some typos in include/linux/preempt.h

There are some typos in the comments of migrate in
include/linux/preempt.h:

  elegible -> eligible
  it's -> its
  migirate_disable -> migrate_disable
  abritrary -> arbitrary

Just fix them.

Signed-off-by: Menglong Dong <[email protected]>

Author: Menglong Dong

include/linux/preempt.h

@@ -372,7 +372,7 @@ static inline void preempt_notifier_init(struct preempt_notifier *notifier,
 /*
  * Migrate-Disable and why it is undesired.
  *
- * When a preempted task becomes elegible to run under the ideal model (IOW it
+ * When a preempted task becomes eligible to run under the ideal model (IOW it
  * becomes one of the M highest priority tasks), it might still have to wait
  * for the preemptee's migrate_disable() section to complete. Thereby suffering
  * a reduction in bandwidth in the exact duration of the migrate_disable()
@@ -387,7 +387,7 @@ static inline void preempt_notifier_init(struct preempt_notifier *notifier,
  * - a lower priority tasks; which under preempt_disable() could've instantly
  *   migrated away when another CPU becomes available, is now constrained
  *   by the ability to push the higher priority task away, which might itself be
- *   in a migrate_disable() section, reducing it's available bandwidth.
+ *   in a migrate_disable() section, reducing its available bandwidth.
  *
  * IOW it trades latency / moves the interference term, but it stays in the
  * system, and as long as it remains unbounded, the system is not fully
@@ -399,15 +399,15 @@ static inline void preempt_notifier_init(struct preempt_notifier *notifier,
  * PREEMPT_RT breaks a number of assumptions traditionally held. By forcing a
  * number of primitives into becoming preemptible, they would also allow
  * migration. This turns out to break a bunch of per-cpu usage. To this end,
- * all these primitives employ migirate_disable() to restore this implicit
+ * all these primitives employ migrate_disable() to restore this implicit
  * assumption.
  *
  * This is a 'temporary' work-around at best. The correct solution is getting
  * rid of the above assumptions and reworking the code to employ explicit
  * per-cpu locking or short preempt-disable regions.
  *
  * The end goal must be to get rid of migrate_disable(), alternatively we need
- * a schedulability theory that does not depend on abritrary migration.
+ * a schedulability theory that does not depend on arbitrary migration.
  *
  *
  * Notes on the implementation.