/*
 * Copyright (c) 2016, NVIDIA CORPORATION.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope 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.
 */

#ifndef __TEGRA_IVC_H

#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <linux/types.h>

struct tegra_ivc_header;

struct tegra_ivc {
	struct device *peer;

	struct {
		struct tegra_ivc_header *channel;
		unsigned int position;
		dma_addr_t phys;
	} rx, tx;

	void (*notify)(struct tegra_ivc *ivc, void *data);
	void *notify_data;

	unsigned int num_frames;
	size_t frame_size;
};

/**
 * tegra_ivc_read_get_next_frame - Peek at the next frame to receive
 * @ivc		pointer of the IVC channel
 *
 * Peek at the next frame to be received, without removing it from
 * the queue.
 *
 * Returns a pointer to the frame, or an error encoded pointer.
 */
void *tegra_ivc_read_get_next_frame(struct tegra_ivc *ivc);

/**
 * tegra_ivc_read_advance - Advance the read queue
 * @ivc		pointer of the IVC channel
 *
 * Advance the read queue
 *
 * Returns 0, or a negative error value if failed.
 */
int tegra_ivc_read_advance(struct tegra_ivc *ivc);

/**
 * tegra_ivc_write_get_next_frame - Poke at the next frame to transmit
 * @ivc		pointer of the IVC channel
 *
 * Get access to the next frame.
 *
 * Returns a pointer to the frame, or an error encoded pointer.
 */
void *tegra_ivc_write_get_next_frame(struct tegra_ivc *ivc);

/**
 * tegra_ivc_write_advance - Advance the write queue
 * @ivc		pointer of the IVC channel
 *
 * Advance the write queue
 *
 * Returns 0, or a negative error value if failed.
 */
int tegra_ivc_write_advance(struct tegra_ivc *ivc);

/**
 * tegra_ivc_notified - handle internal messages
 * @ivc		pointer of the IVC channel
 *
 * This function must be called following every notification.
 *
 * Returns 0 if the channel is ready for communication, or -EAGAIN if a channel
 * reset is in progress.
 */
int tegra_ivc_notified(struct tegra_ivc *ivc);

/**
 * tegra_ivc_reset - initiates a reset of the shared memory state
 * @ivc		pointer of the IVC channel
 *
 * This function must be called after a channel is reserved before it is used
 * for communication. The channel will be ready for use when a subsequent call
 * to notify the remote of the channel reset.
 */
void tegra_ivc_reset(struct tegra_ivc *ivc);

size_t tegra_ivc_align(size_t size);
unsigned tegra_ivc_total_queue_size(unsigned queue_size);
int tegra_ivc_init(struct tegra_ivc *ivc, struct device *peer, void *rx,
		   dma_addr_t rx_phys, void *tx, dma_addr_t tx_phys,
		   unsigned int num_frames, size_t frame_size,
		   void (*notify)(struct tegra_ivc *ivc, void *data),
		   void *data);
void tegra_ivc_cleanup(struct tegra_ivc *ivc);

#endif /* __TEGRA_IVC_H */
=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>net</a>/<a href='/cgit.cgi/linux/net-next.git/commit/net/wireless?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>wireless</a>/<a href='/cgit.cgi/linux/net-next.git/commit/net/wireless/wext-sme.c?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>wext-sme.c</a></div><div class='content'><div class='cgit-panel'><b>diff options</b><form method='get'><input type='hidden' name='h' value='nds-private-remove'/><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/net/wireless/wext-sme.c?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>39cb2c9a316e77f6dfba96c543e55b6672d5a37e</a> (<a href='/cgit.cgi/linux/net-next.git/patch/net/wireless/wext-sme.c?id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>98fe974ee4e20121253de7f61fc8d01bdb3821c1</a> /<a href='/cgit.cgi/linux/net-next.git/tree/net/wireless/wext-sme.c?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>net/wireless/wext-sme.c</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/net/wireless/wext-sme.c?h=nds-private-remove&amp;id=2c5d9555d6d937966d79d4c6529a5f7b9206e405'>2c5d9555d6d937966d79d4c6529a5f7b9206e405</a> (<a href='/cgit.cgi/linux/net-next.git/diff/net/wireless/wext-sme.c?h=nds-private-remove&amp;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/?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>Diffstat</a> (limited to 'net/wireless/wext-sme.c')</div><table summary='diffstat' class='diffstat'>