#ifndef _RDMA_NETLINK_H
#define _RDMA_NETLINK_H


#include <linux/netlink.h>
#include <uapi/rdma/rdma_netlink.h>

struct ibnl_client_cbs {
	int (*dump)(struct sk_buff *skb, struct netlink_callback *nlcb);
	struct module *module;
};

int ibnl_init(void);
void ibnl_cleanup(void);

/**
 * Add a a client to the list of IB netlink exporters.
 * @index: Index of the added client
 * @nops: Number of supported ops by the added client.
 * @cb_table: A table for op->callback
 *
 * Returns 0 on success or a negative error code.
 */
int ibnl_add_client(int index, int nops,
		    const struct ibnl_client_cbs cb_table[]);

/**
 * Remove a client from IB netlink.
 * @index: Index of the removed IB client.
 *
 * Returns 0 on success or a negative error code.
 */
int ibnl_remove_client(int index);

/**
 * Put a new message in a supplied skb.
 * @skb: The netlink skb.
 * @nlh: Pointer to put the header of the new netlink message.
 * @seq: The message sequence number.
 * @len: The requested message length to allocate.
 * @client: Calling IB netlink client.
 * @op: message content op.
 * Returns the allocated buffer on success and NULL on failure.
 */
void *ibnl_put_msg(struct sk_buff *skb, struct nlmsghdr **nlh, int seq,
		   int len, int client, int op, int flags);
/**
 * Put a new attribute in a supplied skb.
 * @skb: The netlink skb.
 * @nlh: Header of the netlink message to append the attribute to.
 * @len: The length of the attribute data.
 * @data: The attribute data to put.
 * @type: The attribute type.
 * Returns the 0 and a negative error code on failure.
 */
int ibnl_put_attr(struct sk_buff *skb, struct nlmsghdr *nlh,
		  int len, void *data, int type);

/**
 * Send the supplied skb to a specific userspace PID.
 * @skb: The netlink skb
 * @nlh: Header of the netlink message to send
 * @pid: Userspace netlink process ID
 * Returns 0 on success or a negative error code.
 */
int ibnl_unicast(struct sk_buff *skb, struct nlmsghdr *nlh,
			__u32 pid);

/**
 * Send the supplied skb to a netlink group.
 * @skb: The netlink skb
 * @nlh: Header of the netlink message to send
 * @group: Netlink group ID
 * @flags: allocation flags
 * Returns 0 on success or a negative error code.
 */
int ibnl_multicast(struct sk_buff *skb, struct nlmsghdr *nlh,
			unsigned int group, gfp_t flags);

/**
 * Check if there are any listeners to the netlink group
 * @group: the netlink group ID
 * Returns 0 on success or a negative for no listeners.
 */
int ibnl_chk_listeners(unsigned int group);

#endif /* _RDMA_NETLINK_H */
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<div class='path'>path: <a href='/cgit.cgi/linux/net-next.git/commit/?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>root</a>/<a href='/cgit.cgi/linux/net-next.git/commit/net?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>net</a>/<a href='/cgit.cgi/linux/net-next.git/commit/net/ipv6?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>ipv6</a>/<a href='/cgit.cgi/linux/net-next.git/commit/net/ipv6/ip6_offload.h?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>ip6_offload.h</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/ipv6/ip6_offload.h?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>39cb2c9a316e77f6dfba96c543e55b6672d5a37e</a> (<a href='/cgit.cgi/linux/net-next.git/patch/net/ipv6/ip6_offload.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/?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>98fe974ee4e20121253de7f61fc8d01bdb3821c1</a> /<a href='/cgit.cgi/linux/net-next.git/tree/net/ipv6/ip6_offload.h?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>net/ipv6/ip6_offload.h</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/net/ipv6/ip6_offload.h?h=nds-private-remove&amp;id=2c5d9555d6d937966d79d4c6529a5f7b9206e405'>2c5d9555d6d937966d79d4c6529a5f7b9206e405</a> (<a href='/cgit.cgi/linux/net-next.git/diff/net/ipv6/ip6_offload.h?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/ipv6/ip6_offload.h')</div><table summary='diffstat' class='diffstat'>