/*
 * Copyright (c) 2016 Tom Haynes <loghyr@primarydata.com>
 *
 * The following implements a super-simple flex-file server
 * where the NFSv4.1 mds is also the ds. And the storage is
 * the same. I.e., writing to the mds via a NFSv4.1 WRITE
 * goes to the same location as the NFSv3 WRITE.
 */
#include <linux/slab.h>

#include <linux/nfsd/debug.h>

#include <linux/sunrpc/addr.h>

#include "flexfilelayoutxdr.h"
#include "pnfs.h"

#define NFSDDBG_FACILITY	NFSDDBG_PNFS

static __be32
nfsd4_ff_proc_layoutget(struct inode *inode, const struct svc_fh *fhp,
		struct nfsd4_layoutget *args)
{
	struct nfsd4_layout_seg *seg = &args->lg_seg;
	u32 device_generation = 0;
	int error;
	uid_t u;

	struct pnfs_ff_layout *fl;

	/*
	 * The super simple flex file server has 1 mirror, 1 data server,
	 * and 1 file handle. So instead of 4 allocs, do 1 for now.
	 * Zero it out for the stateid - don't want junk in there!
	 */
	error = -ENOMEM;
	fl = kzalloc(sizeof(*fl), GFP_KERNEL);
	if (!fl)
		goto out_error;
	args->lg_content = fl;

	/*
	 * Avoid layout commit, try to force the I/O to the DS,
	 * and for fun, cause all IOMODE_RW layout segments to
	 * effectively be WRITE only.
	 */
	fl->flags = FF_FLAGS_NO_LAYOUTCOMMIT | FF_FLAGS_NO_IO_THRU_MDS |
		    FF_FLAGS_NO_READ_IO;

	/* Do not allow a IOMODE_READ segment to have write pemissions */
	if (seg->iomode == IOMODE_READ) {
		u = from_kuid(&init_user_ns, inode->i_uid) + 1;
		fl->uid = make_kuid(&init_user_ns, u);
	} else
		fl->uid = inode->i_uid;
	fl->gid = inode->i_gid;

	error = nfsd4_set_deviceid(&fl->deviceid, fhp, device_generation);
	if (error)
		goto out_error;

	fl->fh.size = fhp->fh_handle.fh_size;
	memcpy(fl->fh.data, &fhp->fh_handle.fh_base, fl->fh.size);

	/* Give whole file layout segments */
	seg->offset = 0;
	seg->length = NFS4_MAX_UINT64;

	dprintk("GET: 0x%llx:0x%llx %d\n", seg->offset, seg->length,
		seg->iomode);
	return 0;

out_error:
	seg->length = 0;
	return nfserrno(error);
}

static __be32
nfsd4_ff_proc_getdeviceinfo(struct super_block *sb, struct svc_rqst *rqstp,
		struct nfs4_client *clp, struct nfsd4_getdeviceinfo *gdp)
{
	struct pnfs_ff_device_addr *da;

	u16 port;
	char addr[INET6_ADDRSTRLEN];

	da = kzalloc(sizeof(struct pnfs_ff_device_addr), GFP_KERNEL);
	if (!da)
		return nfserrno(-ENOMEM);

	gdp->gd_device = da;

	da->version = 3;
	da->minor_version = 0;

	da->rsize = svc_max_payload(rqstp);
	da->wsize = da->rsize;

	rpc_ntop((struct sockaddr *)&rqstp->rq_daddr,
		 addr, INET6_ADDRSTRLEN);
	if (rqstp->rq_daddr.ss_family == AF_INET) {
		struct sockaddr_in *sin;

		sin = (struct sockaddr_in *)&rqstp->rq_daddr;
		port = ntohs(sin->sin_port);
		snprintf(da->netaddr.netid, FF_NETID_LEN + 1, "tcp");
		da->netaddr.netid_len = 3;
	} else {
		struct sockaddr_in6 *sin6;

		sin6 = (struct sockaddr_in6 *)&rqstp->rq_daddr;
		port = ntohs(sin6->sin6_port);
		snprintf(da->netaddr.netid, FF_NETID_LEN + 1, "tcp6");
		da->netaddr.netid_len = 4;
	}

	da->netaddr.addr_len =
		snprintf(da->netaddr.addr, FF_ADDR_LEN + 1,
			 "%s.%hhu.%hhu", addr, port >> 8, port & 0xff);

	da->tightly_coupled = false;

	return 0;
}

const struct nfsd4_layout_ops ff_layout_ops = {
	.notify_types		=
			NOTIFY_DEVICEID4_DELETE | NOTIFY_DEVICEID4_CHANGE,
	.disable_recalls	= true,
	.proc_getdeviceinfo	= nfsd4_ff_proc_getdeviceinfo,
	.encode_getdeviceinfo	= nfsd4_ff_encode_getdeviceinfo,
	.proc_layoutget		= nfsd4_ff_proc_layoutget,
	.encode_layoutget	= nfsd4_ff_encode_layoutget,
};
'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/drivers/usb/atm?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>39cb2c9a316e77f6dfba96c543e55b6672d5a37e</a> (<a href='/cgit.cgi/linux/net-next.git/patch/drivers/usb/atm?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/drivers/usb/atm?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>drivers/usb/atm</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/drivers/usb/atm?h=nds-private-remove&amp;id=2c5d9555d6d937966d79d4c6529a5f7b9206e405'>2c5d9555d6d937966d79d4c6529a5f7b9206e405</a> (<a href='/cgit.cgi/linux/net-next.git/diff/drivers/usb/atm?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 'drivers/usb/atm')</div><table summary='diffstat' class='diffstat'>