/*
 * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
 * Copyright (C) 2004-2006 Red Hat, Inc.  All rights reserved.
 *
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
 * of the GNU General Public License version 2.
 */

#ifndef __LOG_DOT_H__
#define __LOG_DOT_H__

#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/writeback.h>
#include "incore.h"

/**
 * gfs2_log_lock - acquire the right to mess with the log manager
 * @sdp: the filesystem
 *
 */

static inline void gfs2_log_lock(struct gfs2_sbd *sdp)
__acquires(&sdp->sd_log_lock)
{
	spin_lock(&sdp->sd_log_lock);
}

/**
 * gfs2_log_unlock - release the right to mess with the log manager
 * @sdp: the filesystem
 *
 */

static inline void gfs2_log_unlock(struct gfs2_sbd *sdp)
__releases(&sdp->sd_log_lock)
{
	spin_unlock(&sdp->sd_log_lock);
}

static inline void gfs2_log_pointers_init(struct gfs2_sbd *sdp,
					  unsigned int value)
{
	if (++value == sdp->sd_jdesc->jd_blocks) {
		value = 0;
	}
	sdp->sd_log_head = sdp->sd_log_tail = value;
}

static inline void gfs2_ordered_add_inode(struct gfs2_inode *ip)
{
	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);

	if (!test_bit(GIF_ORDERED, &ip->i_flags)) {
		spin_lock(&sdp->sd_ordered_lock);
		if (!test_and_set_bit(GIF_ORDERED, &ip->i_flags))
			list_add(&ip->i_ordered, &sdp->sd_log_le_ordered);
		spin_unlock(&sdp->sd_ordered_lock);
	}
}
extern void gfs2_ordered_del_inode(struct gfs2_inode *ip);
extern unsigned int gfs2_struct2blk(struct gfs2_sbd *sdp, unsigned int nstruct,
			    unsigned int ssize);

extern void gfs2_log_release(struct gfs2_sbd *sdp, unsigned int blks);
extern int gfs2_log_reserve(struct gfs2_sbd *sdp, unsigned int blks);
enum gfs2_flush_type {
	NORMAL_FLUSH = 0,
	SYNC_FLUSH,
	SHUTDOWN_FLUSH,
	FREEZE_FLUSH
};
extern void gfs2_log_flush(struct gfs2_sbd *sdp, struct gfs2_glock *gl,
			   enum gfs2_flush_type type);
extern void gfs2_log_commit(struct gfs2_sbd *sdp, struct gfs2_trans *trans);
extern void gfs2_remove_from_ail(struct gfs2_bufdata *bd);
extern void gfs2_ail1_flush(struct gfs2_sbd *sdp, struct writeback_control *wbc);

extern void gfs2_log_shutdown(struct gfs2_sbd *sdp);
extern int gfs2_logd(void *data);
extern void gfs2_add_revoke(struct gfs2_sbd *sdp, struct gfs2_bufdata *bd);
extern void gfs2_write_revokes(struct gfs2_sbd *sdp);

#endif /* __LOG_DOT_H__ */
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<div class='path'>path: <a href='/cgit.cgi/linux/net-next.git/commit/?id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>root</a>/<a href='/cgit.cgi/linux/net-next.git/commit/drivers?id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>drivers</a>/<a href='/cgit.cgi/linux/net-next.git/commit/drivers/virtio?id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>virtio</a>/<a href='/cgit.cgi/linux/net-next.git/commit/drivers/virtio/Makefile?id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>Makefile</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/drivers/virtio/Makefile?id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>39cb2c9a316e77f6dfba96c543e55b6672d5a37e</a> (<a href='/cgit.cgi/linux/net-next.git/patch/drivers/virtio/Makefile?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/drivers/virtio/Makefile?id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>drivers/virtio/Makefile</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/drivers/virtio/Makefile?id=2c5d9555d6d937966d79d4c6529a5f7b9206e405'>2c5d9555d6d937966d79d4c6529a5f7b9206e405</a> (<a href='/cgit.cgi/linux/net-next.git/diff/drivers/virtio/Makefile?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 'drivers/virtio/Makefile')</div><table summary='diffstat' class='diffstat'>