/*
 * Definitions for measuring cputime in nsecs resolution.
 *
 * Based on <arch/ia64/include/asm/cputime.h>
 *
 * Copyright (C) 2007 FUJITSU LIMITED
 * Copyright (C) 2007 Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
 *
 * This program 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.
 *
 */

#ifndef _ASM_GENERIC_CPUTIME_NSECS_H
#define _ASM_GENERIC_CPUTIME_NSECS_H

#include <linux/math64.h>

typedef u64 __nocast cputime_t;
typedef u64 __nocast cputime64_t;

#define cmpxchg_cputime(ptr, old, new) cmpxchg64(ptr, old, new)

#define cputime_one_jiffy		jiffies_to_cputime(1)

#define cputime_div(__ct, divisor)  div_u64((__force u64)__ct, divisor)
#define cputime_div_rem(__ct, divisor, remainder) \
	div_u64_rem((__force u64)__ct, divisor, remainder);

/*
 * Convert cputime <-> jiffies (HZ)
 */
#define cputime_to_jiffies(__ct)	\
	cputime_div(__ct, NSEC_PER_SEC / HZ)
#define jiffies_to_cputime(__jif)	\
	(__force cputime_t)((__jif) * (NSEC_PER_SEC / HZ))
#define cputime64_to_jiffies64(__ct)	\
	cputime_div(__ct, NSEC_PER_SEC / HZ)
#define jiffies64_to_cputime64(__jif)	\
	(__force cputime64_t)((__jif) * (NSEC_PER_SEC / HZ))


/*
 * Convert cputime <-> nanoseconds
 */
#define cputime_to_nsecs(__ct)		\
	(__force u64)(__ct)
#define nsecs_to_cputime(__nsecs)	\
	(__force cputime_t)(__nsecs)
#define nsecs_to_cputime64(__nsecs)	\
	(__force cputime64_t)(__nsecs)


/*
 * Convert cputime <-> microseconds
 */
#define cputime_to_usecs(__ct)		\
	cputime_div(__ct, NSEC_PER_USEC)
#define usecs_to_cputime(__usecs)	\
	(__force cputime_t)((__usecs) * NSEC_PER_USEC)
#define usecs_to_cputime64(__usecs)	\
	(__force cputime64_t)((__usecs) * NSEC_PER_USEC)

/*
 * Convert cputime <-> seconds
 */
#define cputime_to_secs(__ct)		\
	cputime_div(__ct, NSEC_PER_SEC)
#define secs_to_cputime(__secs)		\
	(__force cputime_t)((__secs) * NSEC_PER_SEC)

/*
 * Convert cputime <-> timespec (nsec)
 */
static inline cputime_t timespec_to_cputime(const struct timespec *val)
{
	u64 ret = (u64)val->tv_sec * NSEC_PER_SEC + val->tv_nsec;
	return (__force cputime_t) ret;
}
static inline void cputime_to_timespec(const cputime_t ct, struct timespec *val)
{
	u32 rem;

	val->tv_sec = cputime_div_rem(ct, NSEC_PER_SEC, &rem);
	val->tv_nsec = rem;
}

/*
 * Convert cputime <-> timeval (msec)
 */
static inline cputime_t timeval_to_cputime(const struct timeval *val)
{
	u64 ret = (u64)val->tv_sec * NSEC_PER_SEC +
			val->tv_usec * NSEC_PER_USEC;
	return (__force cputime_t) ret;
}
static inline void cputime_to_timeval(const cputime_t ct, struct timeval *val)
{
	u32 rem;

	val->tv_sec = cputime_div_rem(ct, NSEC_PER_SEC, &rem);
	val->tv_usec = rem / NSEC_PER_USEC;
}

/*
 * Convert cputime <-> clock (USER_HZ)
 */
#define cputime_to_clock_t(__ct)	\
	cputime_div(__ct, (NSEC_PER_SEC / USER_HZ))
#define clock_t_to_cputime(__x)		\
	(__force cputime_t)((__x) * (NSEC_PER_SEC / USER_HZ))

/*
 * Convert cputime64 to clock.
 */
#define cputime64_to_clock_t(__ct)	\
	cputime_to_clock_t((__force cputime_t)__ct)

#endif
git/commit/include/net/caif/caif_device.h?id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>caif_device.h</a></div><div class='content'><div class='cgit-panel'><b>diff options</b><form method='get'><input type='hidden' name='id' value='39cb2c9a316e77f6dfba96c543e55b6672d5a37e'/><table><tr><td colspan='2'/></tr><tr><td class='label'>context:</td><td class='ctrl'><select name='context' onchange='this.form.submit();'><option value='1'>1</option><option value='2'>2</option><option value='3' selected='selected'>3</option><option value='4'>4</option><option value='5'>5</option><option value='6'>6</option><option value='7'>7</option><option value='8'>8</option><option value='9'>9</option><option value='10'>10</option><option value='15'>15</option><option value='20'>20</option><option value='25'>25</option><option value='30'>30</option><option value='35'>35</option><option value='40'>40</option></select></td></tr><tr><td class='label'>space:</td><td class='ctrl'><select name='ignorews' onchange='this.form.submit();'><option value='0' selected='selected'>include</option><option value='1'>ignore</option></select></td></tr><tr><td class='label'>mode:</td><td class='ctrl'><select name='dt' onchange='this.form.submit();'><option value='0' selected='selected'>unified</option><option value='1'>ssdiff</option><option value='2'>stat only</option></select></td></tr><tr><td/><td class='ctrl'><noscript><input type='submit' value='reload'/></noscript></td></tr></table></form></div><table summary='commit info' class='commit-info'>
<tr><th>author</th><td>Linus Torvalds &lt;torvalds@linux-foundation.org&gt;</td><td class='right'>2017-01-29 13:50:06 -0800</td></tr>
<tr><th>committer</th><td>Linus Torvalds &lt;torvalds@linux-foundation.org&gt;</td><td class='right'>2017-01-29 13:50:06 -0800</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/include/net/caif/caif_device.h?id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>39cb2c9a316e77f6dfba96c543e55b6672d5a37e</a> (<a href='/cgit.cgi/linux/net-next.git/patch/include/net/caif/caif_device.h?id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>98fe974ee4e20121253de7f61fc8d01bdb3821c1</a> /<a href='/cgit.cgi/linux/net-next.git/tree/include/net/caif/caif_device.h?id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>include/net/caif/caif_device.h</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/include/net/caif/caif_device.h?id=2c5d9555d6d937966d79d4c6529a5f7b9206e405'>2c5d9555d6d937966d79d4c6529a5f7b9206e405</a> (<a href='/cgit.cgi/linux/net-next.git/diff/include/net/caif/caif_device.h?id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e&amp;id2=2c5d9555d6d937966d79d4c6529a5f7b9206e405'>diff</a>)</td></tr></table>
<div class='commit-subject'>drm/i915: Check for NULL i915_vma in intel_unpin_fb_obj()</div><div class='commit-msg'>I've seen this trigger twice now, where the i915_gem_object_to_ggtt()
call in intel_unpin_fb_obj() returns NULL, resulting in an oops
immediately afterwards as the (inlined) call to i915_vma_unpin_fence()
tries to dereference it.

It seems to be some race condition where the object is going away at
shutdown time, since both times happened when shutting down the X
server.  The call chains were different:

 - VT ioctl(KDSETMODE, KD_TEXT):

    intel_cleanup_plane_fb+0x5b/0xa0 [i915]
    drm_atomic_helper_cleanup_planes+0x6f/0x90 [drm_kms_helper]
    intel_atomic_commit_tail+0x749/0xfe0 [i915]
    intel_atomic_commit+0x3cb/0x4f0 [i915]
    drm_atomic_commit+0x4b/0x50 [drm]
    restore_fbdev_mode+0x14c/0x2a0 [drm_kms_helper]
    drm_fb_helper_restore_fbdev_mode_unlocked+0x34/0x80 [drm_kms_helper]
    drm_fb_helper_set_par+0x2d/0x60 [drm_kms_helper]
    intel_fbdev_set_par+0x18/0x70 [i915]
    fb_set_var+0x236/0x460
    fbcon_blank+0x30f/0x350
    do_unblank_screen+0xd2/0x1a0
    vt_ioctl+0x507/0x12a0
    tty_ioctl+0x355/0xc30
    do_vfs_ioctl+0xa3/0x5e0
    SyS_ioctl+0x79/0x90
    entry_SYSCALL_64_fastpath+0x13/0x94

 - i915 unpin_work workqueue:

    intel_unpin_work_fn+0x58/0x140 [i915]
    process_one_work+0x1f1/0x480
    worker_thread+0x48/0x4d0
    kthread+0x101/0x140

and this patch purely papers over the issue by adding a NULL pointer
check and a WARN_ON_ONCE() to avoid the oops that would then generally
make the machine unresponsive.

Other callers of i915_gem_object_to_ggtt() seem to also check for the
returned pointer being NULL and warn about it, so this clearly has
happened before in other places.

[ Reported it originally to the i915 developers on Jan 8, applying the
  ugly workaround on my own now after triggering the problem for the
  second time with no feedback.

  This is likely to be the same bug reported as

     https://bugs.freedesktop.org/show_bug.cgi?id=98829
     https://bugs.freedesktop.org/show_bug.cgi?id=99134

  which has a patch for the underlying problem, but it hasn't gotten to
  me, so I'm applying the workaround. ]

Cc: Daniel Vetter &lt;daniel.vetter@intel.com&gt;
Cc: Jani Nikula &lt;jani.nikula@linux.intel.com&gt;
Cc: Ville Syrjälä &lt;ville.syrjala@linux.intel.com&gt;
Cc: Chris Wilson &lt;chris@chris-wilson.co.uk&gt;
Cc: Maarten Lankhorst &lt;maarten.lankhorst@linux.intel.com&gt;
Cc: Tvrtko Ursulin &lt;tvrtko.ursulin@intel.com&gt;
Cc: Imre Deak &lt;imre.deak@intel.com&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>Diffstat</a> (limited to 'include/net/caif/caif_device.h')</div><table summary='diffstat' class='diffstat'>