svn commit: r326376 - head/sys/kern

[Hans Petter Selasky]

Author: hselasky
Date: Wed Nov 29 23:28:40 2017
New Revision: 326376
URL: https://svnweb.freebsd.org/changeset/base/326376

Log:
  The sched_add() function is not only used when the thread is initially
  started, but also by the turnstiles to mark a thread as runnable for
  all locks, for instance sleepqueues do:
  setrunnable()->sched_wakeup()->sched_add()
  
  In r326218 code was added to allow booting from non-zero CPU numbers
  by setting the ts_cpu field inside the ULE scheduler's sched_add()
  function. This had an undesired side-effect that prior sched_pin() and
  sched_bind() calls got disregarded. This patch fixes the
  initialization of the ts_cpu field for the ULE scheduler to only
  happen once when the initial thread is constructed during system
  init. Forking will then later on ensure that a valid ts_cpu value gets
  copied to all children.
  
  Reviewed by:	jhb, kib
  Discussed with:	nwhitehorn
  MFC after:	1 month
  Differential revision:	https://reviews.freebsd.org/D13298
  Sponsored by:	Mellanox Technologies

Modified:
  head/sys/kern/sched_ule.c

Modified: head/sys/kern/sched_ule.c
==============================================================================
--- head/sys/kern/sched_ule.c	Wed Nov 29 21:16:14 2017	(r326375)
+++ head/sys/kern/sched_ule.c	Wed Nov 29 23:28:40 2017	(r326376)
@@ -1405,7 +1405,6 @@ sched_setup(void *dummy)
 
 	/* Add thread0's load since it's running. */
 	TDQ_LOCK(tdq);
-	td_get_sched(&thread0)->ts_cpu = curcpu; /* Something valid to start */
 	thread0.td_lock = TDQ_LOCKPTR(TDQ_SELF());
 	tdq_load_add(tdq, &thread0);
 	tdq->tdq_lowpri = thread0.td_priority;
@@ -1642,6 +1641,7 @@ schedinit(void)
 	ts0->ts_ltick = ticks;
 	ts0->ts_ftick = ticks;
 	ts0->ts_slice = 0;
+	ts0->ts_cpu = curcpu;	/* set valid CPU number */
 }
 
 /*
@@ -2453,7 +2453,6 @@ sched_add(struct thread *td, int flags)
 	 * Pick the destination cpu and if it isn't ours transfer to the
 	 * target cpu.
 	 */
-	td_get_sched(td)->ts_cpu = curcpu; /* Pick something valid to start */
 	cpu = sched_pickcpu(td, flags);
 	tdq = sched_setcpu(td, cpu, flags);
 	tdq_add(tdq, td, flags);