Emulate illumos interface cv_timedwait_hires()

Needed for Illumos #3582. This interface is supposed to support
a variable-resolution timeout with nanosecond granularity.  This
implementation rounds up to microsecond resolution, as nanosecond-
precision timing is rarely needed for real-world performance
tuning and may incur unnecessary busy-waiting.  usleep_range() is
used if available, otherwise udelay() or msleep() are used
depending on the length of the delay interval.

Add flags from sys/callo.h as these are used to control the behavior of
cv_timedwait_hires().  Specifically,

CALLOUT_FLAG_ABSOLUTE
    Normally, the expiration passed to the timeout API functions is
    an expiration interval. If this flag is specified, then it is
    interpreted as the expiration time itself.

CALLOUT_FLAG_ROUNDUP
    Roundup the expiration time to the next resolution boundary. If this
    flag is not specified, the expiration time is rounded down.

References:
    https://www.illumos.org/issues/3582
    illumos/illumos-gate@0689f76

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #304

include/sys/Makefile.am

@@ -13,6 +13,7 @@ KERNEL_H = \
 	$(top_srcdir)/include/sys/buf.h \
 	$(top_srcdir)/include/sys/byteorder.h \
 	$(top_srcdir)/include/sys/callb.h \
+	$(top_srcdir)/include/sys/callo.h \
 	$(top_srcdir)/include/sys/cmn_err.h \
 	$(top_srcdir)/include/sys/compress.h \
 	$(top_srcdir)/include/sys/condvar.h \

include/sys/callo.h

@@ -0,0 +1,52 @@
+/*****************************************************************************\
+ *  Copyright (C) 2007-2013 Lawrence Livermore National Security, LLC.
+ *  Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
+ *  Written by Brian Behlendorf <behlendorf1@llnl.gov>.
+ *  UCRL-CODE-235197
+ *
+ *  This file is part of the SPL, Solaris Porting Layer.
+ *  For details, see <http://zfsonlinux.org/>.
+ *
+ *  The SPL is free software; you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License as published by the
+ *  Free Software Foundation; either version 2 of the License, or (at your
+ *  option) any later version.
+ *
+ *  The SPL is distributed in the hope that it will be useful, but WITHOUT
+ *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ *  for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with the SPL.  If not, see <http://www.gnu.org/licenses/>.
+\*****************************************************************************/
+
+#ifndef _SPL_CALLO_H
+#define _SPL_CALLO_H
+
+/*
+ * Callout flags:
+ *
+ * CALLOUT_FLAG_ROUNDUP
+ *      Roundup the expiration time to the next resolution boundary.
+ *      If this flag is not specified, the expiration time is rounded down.
+ * CALLOUT_FLAG_ABSOLUTE
+ *      Normally, the expiration passed to the timeout API functions is an
+ *      expiration interval. If this flag is specified, then it is
+ *      interpreted as the expiration time itself.
+ * CALLOUT_FLAG_HRESTIME
+ *      Normally, callouts are not affected by changes to system time
+ *      (hrestime). This flag is used to create a callout that is affected
+ *      by system time. If system time changes, these timers must be
+ *      handled in a special way (see callout.c). These are used by condition
+ *      variables and LWP timers that need this behavior.
+ * CALLOUT_FLAG_32BIT
+ *      Legacy interfaces timeout() and realtime_timeout() pass this flag
+ *      to timeout_generic() to indicate that a 32-bit ID should be allocated.
+ */
+#define CALLOUT_FLAG_ROUNDUP            0x1
+#define CALLOUT_FLAG_ABSOLUTE           0x2
+#define CALLOUT_FLAG_HRESTIME           0x4
+#define CALLOUT_FLAG_32BIT              0x8
+
+#endif  /* _SPL_CALLB_H */

include/sys/condvar.h

@@ -27,8 +27,10 @@
 
 #include <linux/module.h>
 #include <linux/wait.h>
+#include <linux/delay_compat.h>
 #include <sys/kmem.h>
 #include <sys/mutex.h>
+#include <sys/callo.h>
 
 /*
  * The kcondvar_t struct is protected by mutex taken externally before
@@ -56,6 +58,8 @@ extern void __cv_wait_interruptible(kcondvar_t *cvp, kmutex_t *mp);
 extern clock_t __cv_timedwait(kcondvar_t *cvp, kmutex_t *mp, clock_t exp_time);
 extern clock_t __cv_timedwait_interruptible(kcondvar_t *cvp, kmutex_t *mp,
 	clock_t exp_time);
+extern	clock_t	cv_timedwait_hires(kcondvar_t *cvp, kmutex_t *mp,
+	hrtime_t tim, hrtime_t res, int flag);
 extern void __cv_signal(kcondvar_t *cvp);
 extern void __cv_broadcast(kcondvar_t *cvp);
 

include/sys/time.h

@@ -47,6 +47,9 @@
 #define MICROSEC			1000000
 #define NANOSEC				1000000000
 
+#define	MSEC2NSEC(m)	((hrtime_t)(m) * (NANOSEC / MILLISEC))
+#define	NSEC2MSEC(n)	((n) / (NANOSEC / MILLISEC))
+
 /* Already defined in include/linux/time.h */
 #undef CLOCK_THREAD_CPUTIME_ID
 #undef CLOCK_REALTIME