Avoid to check the same cache line/variable from all the locking

primitives by breaking stop_scheduler into a per-thread variable.
Also, store the new td_stopsched very close to td_*locks members as
they will be accessed mostly in the same codepaths as td_stopsched and
this results in avoiding a further cache-line pollution, possibly.

STOP_SCHEDULER() was pondered to use a new 'thread' argument, in order to
take advantage of already cached curthread, but in the end there should
not really be a performance benefit, while introducing a KPI breakage.

In collabouration with:	flo
Reviewed by:	avg
MFC after:	3 months (or never)
X-MFC:		r228424

sys/dev/usb/usb_transfer.c

@@ -42,6 +42,7 @@
 #include <sys/callout.h>
 #include <sys/malloc.h>
 #include <sys/priv.h>
+#include <sys/proc.h>
 
 #include <dev/usb/usb.h>
 #include <dev/usb/usbdi.h>

sys/geom/geom_bsd.c

@@ -57,6 +57,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/errno.h>
 #include <sys/disklabel.h>
 #include <sys/gpt.h>
+#include <sys/proc.h>
 #include <sys/sbuf.h>
 #include <sys/uuid.h>
 #include <geom/geom.h>

sys/geom/geom_mbr.c

@@ -45,6 +45,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/lock.h>
 #include <sys/mutex.h>
 #include <sys/md5.h>
+#include <sys/proc.h>
 
 #include <sys/diskmbr.h>
 #include <sys/sbuf.h>

sys/geom/geom_pc98.c

@@ -43,6 +43,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/bio.h>
 #include <sys/lock.h>
 #include <sys/mutex.h>
+#include <sys/proc.h>
 #include <sys/sbuf.h>
 
 #include <sys/diskpc98.h>

sys/geom/mountver/g_mountver.c

@@ -36,6 +36,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/mutex.h>
 #include <sys/bio.h>
 #include <sys/disk.h>
+#include <sys/proc.h>
 #include <sys/sbuf.h>
 #include <sys/sysctl.h>
 #include <sys/malloc.h>

sys/kern/kern_shutdown.c

@@ -145,7 +145,6 @@ SYSCTL_INT(_kern_shutdown, OID_AUTO, show_busybufs, CTLFLAG_RW,
  */
 const char *panicstr;
 
-int stop_scheduler;			/* system stopped CPUs for panic */
 int dumping;				/* system is dumping */
 int rebooting;				/* system is rebooting */
 static struct dumperinfo dumper;	/* our selected dumper */
@@ -597,7 +596,7 @@ panic(const char *fmt, ...)
 		 * stop_scheduler_on_panic is true, then stop_scheduler will
 		 * always be set.  Even if panic has been entered from kdb.
 		 */
-		stop_scheduler = 1;
+		td->td_stopsched = 1;
 	}
 #endif
 

sys/sys/proc.h

@@ -235,6 +235,7 @@ struct thread {
 	short		td_locks;	/* (k) Count of non-spin locks. */
 	short		td_rw_rlocks;	/* (k) Count of rwlock read locks. */
 	short		td_lk_slocks;	/* (k) Count of lockmgr shared locks. */
+	short		td_stopsched;	/* (k) Scheduler stopped. */
 	struct turnstile *td_blocked;	/* (t) Lock thread is blocked on. */
 	const char	*td_lockname;	/* (t) Name of lock blocked on. */
 	LIST_HEAD(, turnstile) td_contested;	/* (q) Contested locks. */

sys/sys/systm.h

@@ -47,7 +47,6 @@
 
 extern int cold;		/* nonzero if we are doing a cold boot */
 extern int rebooting;		/* kern_reboot() has been called. */
-extern int stop_scheduler;	/* only one thread runs after panic */
 extern const char *panicstr;	/* panic message */
 extern char version[];		/* system version */
 extern char copyright[];	/* system copyright */
@@ -113,7 +112,7 @@ enum VM_GUEST { VM_GUEST_NO = 0, VM_GUEST_VM, VM_GUEST_XEN };
  * Otherwise, the kernel will deadlock since the scheduler isn't
  * going to run the thread that holds any lock we need.
  */
-#define	SCHEDULER_STOPPED() __predict_false(stop_scheduler)
+#define	SCHEDULER_STOPPED() __predict_false(curthread->td_stopsched)
 
 /*
  * XXX the hints declarations are even more misplaced than most declarations