/* net/atm/signaling.c - ATM signaling */

/* Written 1995-2000 by Werner Almesberger, EPFL LRC/ICA */

#define pr_fmt(fmt) KBUILD_MODNAME ":%s: " fmt, __func__

#include <linux/errno.h>	/* error codes */
#include <linux/kernel.h>	/* printk */
#include <linux/skbuff.h>
#include <linux/wait.h>
#include <linux/sched.h>	/* jiffies and HZ */
#include <linux/atm.h>		/* ATM stuff */
#include <linux/atmsap.h>
#include <linux/atmsvc.h>
#include <linux/atmdev.h>
#include <linux/bitops.h>
#include <linux/slab.h>

#include "resources.h"
#include "signaling.h"

struct atm_vcc *sigd = NULL;

static void sigd_put_skb(struct sk_buff *skb)
{
	if (!sigd) {
		pr_debug("atmsvc: no signaling daemon\n");
		kfree_skb(skb);
		return;
	}
	atm_force_charge(sigd, skb->truesize);
	skb_queue_tail(&sk_atm(sigd)->sk_receive_queue, skb);
	sk_atm(sigd)->sk_data_ready(sk_atm(sigd));
}

static void modify_qos(struct atm_vcc *vcc, struct atmsvc_msg *msg)
{
	struct sk_buff *skb;

	if (test_bit(ATM_VF_RELEASED, &vcc->flags) ||
	    !test_bit(ATM_VF_READY, &vcc->flags))
		return;
	msg->type = as_error;
	if (!vcc->dev->ops->change_qos)
		msg->reply = -EOPNOTSUPP;
	else {
		/* should lock VCC */
		msg->reply = vcc->dev->ops->change_qos(vcc, &msg->qos,
						       msg->reply);
		if (!msg->reply)
			msg->type = as_okay;
	}
	/*
	 * Should probably just turn around the old skb. But the, the buffer
	 * space accounting needs to follow the change too. Maybe later.
	 */
	while (!(skb = alloc_skb(sizeof(struct atmsvc_msg), GFP_KERNEL)))
		schedule();
	*(struct atmsvc_msg *)skb_put(skb, sizeof(struct atmsvc_msg)) = *msg;
	sigd_put_skb(skb);
}

static int sigd_send(struct atm_vcc *vcc, struct sk_buff *skb)
{
	struct atmsvc_msg *msg;
	struct atm_vcc *session_vcc;
	struct sock *sk;

	msg = (struct atmsvc_msg *) skb->data;
	atomic_sub(skb->truesize, &sk_atm(vcc)->sk_wmem_alloc);
	vcc = *(struct atm_vcc **) &msg->vcc;
	pr_debug("%d (0x%lx)\n", (int)msg->type, (unsigned long)vcc);
	sk = sk_atm(vcc);

	switch (msg->type) {
	case as_okay:
		sk->sk_err = -msg->reply;
		clear_bit(ATM_VF_WAITING, &vcc->flags);
		if (!*vcc->local.sas_addr.prv && !*vcc->local.sas_addr.pub) {
			vcc->local.sas_family = AF_ATMSVC;
			memcpy(vcc->local.sas_addr.prv,
			       msg->local.sas_addr.prv, ATM_ESA_LEN);
			memcpy(vcc->local.sas_addr.pub,
			       msg->local.sas_addr.pub, ATM_E164_LEN + 1);
		}
		session_vcc = vcc->session ? vcc->session : vcc;
		if (session_vcc->vpi || session_vcc->vci)
			break;
		session_vcc->itf = msg->pvc.sap_addr.itf;
		session_vcc->vpi = msg->pvc.sap_addr.vpi;
		session_vcc->vci = msg->pvc.sap_addr.vci;
		if (session_vcc->vpi || session_vcc->vci)
			session_vcc->qos = msg->qos;
		break;
	case as_error:
		clear_bit(ATM_VF_REGIS, &vcc->flags);
		clear_bit(ATM_VF_READY, &vcc->flags);
		sk->sk_err = -msg->reply;
		clear_bit(ATM_VF_WAITING, &vcc->flags);
		break;
	case as_indicate:
		vcc = *(struct atm_vcc **)&msg->listen_vcc;
		sk = sk_atm(vcc);
		pr_debug("as_indicate!!!\n");
		lock_sock(sk);
		if (sk_acceptq_is_full(sk)) {
			sigd_enq(NULL, as_reject, vcc, NULL, NULL);
			dev_kfree_skb(skb);
			goto as_indicate_complete;
		}
		sk->sk_ack_backlog++;
		skb_queue_tail(&sk->sk_receive_queue, skb);
		pr_debug("waking sk_sleep(sk) 0x%p\n", sk_sleep(sk));
		sk->sk_state_change(sk);
as_indicate_complete:
		release_sock(sk);
		return 0;
	case as_close:
		set_bit(ATM_VF_RELEASED, &vcc->flags);
		vcc_release_async(vcc, msg->reply);
		goto out;
	case as_modify:
		modify_qos(vcc, msg);
		break;
	case as_addparty:
	case as_dropparty:
		sk->sk_err_soft = -msg->reply;
					/* < 0 failure, otherwise ep_ref */
		clear_bit(ATM_VF_WAITING, &vcc->flags);
		break;
	default:
		pr_alert("bad message type %d\n", (int)msg->type);
		return -EINVAL;
	}
	sk->sk_state_change(sk);
out:
	dev_kfree_skb(skb);
	return 0;
}

void sigd_enq2(struct atm_vcc *vcc, enum atmsvc_msg_type type,
	       struct atm_vcc *listen_vcc, const struct sockaddr_atmpvc *pvc,
	       const struct sockaddr_atmsvc *svc, const struct atm_qos *qos,
	       int reply)
{
	struct sk_buff *skb;
	struct atmsvc_msg *msg;
	static unsigned int session = 0;

	pr_debug("%d (0x%p)\n", (int)type, vcc);
	while (!(skb = alloc_skb(sizeof(struct atmsvc_msg), GFP_KERNEL)))
		schedule();
	msg = (struct atmsvc_msg *)skb_put(skb, sizeof(struct atmsvc_msg));
	memset(msg, 0, sizeof(*msg));
	msg->type = type;
	*(struct atm_vcc **) &msg->vcc = vcc;
	*(struct atm_vcc **) &msg->listen_vcc = listen_vcc;
	msg->reply = reply;
	if (qos)
		msg->qos = *qos;
	if (vcc)
		msg->sap = vcc->sap;
	if (svc)
		msg->svc = *svc;
	if (vcc)
		msg->local = vcc->local;
	if (pvc)
		msg->pvc = *pvc;
	if (vcc) {
		if (type == as_connect && test_bit(ATM_VF_SESSION, &vcc->flags))
			msg->session = ++session;
			/* every new pmp connect gets the next session number */
	}
	sigd_put_skb(skb);
	if (vcc)
		set_bit(ATM_VF_REGIS, &vcc->flags);
}

void sigd_enq(struct atm_vcc *vcc, enum atmsvc_msg_type type,
	      struct atm_vcc *listen_vcc, const struct sockaddr_atmpvc *pvc,
	      const struct sockaddr_atmsvc *svc)
{
	sigd_enq2(vcc, type, listen_vcc, pvc, svc, vcc ? &vcc->qos : NULL, 0);
	/* other ISP applications may use "reply" */
}

static void purge_vcc(struct atm_vcc *vcc)
{
	if (sk_atm(vcc)->sk_family == PF_ATMSVC &&
	    !test_bit(ATM_VF_META, &vcc->flags)) {
		set_bit(ATM_VF_RELEASED, &vcc->flags);
		clear_bit(ATM_VF_REGIS, &vcc->flags);
		vcc_release_async(vcc, -EUNATCH);
	}
}

static void sigd_close(struct atm_vcc *vcc)
{
	struct sock *s;
	int i;

	pr_debug("\n");
	sigd = NULL;
	if (skb_peek(&sk_atm(vcc)->sk_receive_queue))
		pr_err("closing with requests pending\n");
	skb_queue_purge(&sk_atm(vcc)->sk_receive_queue);

	read_lock(&vcc_sklist_lock);
	for (i = 0; i < VCC_HTABLE_SIZE; ++i) {
		struct hlist_head *head = &vcc_hash[i];

		sk_for_each(s, head) {
			vcc = atm_sk(s);

			purge_vcc(vcc);
		}
	}
	read_unlock(&vcc_sklist_lock);
}

static struct atmdev_ops sigd_dev_ops = {
	.close = sigd_close,
	.send =	sigd_send
};

static struct atm_dev sigd_dev = {
	.ops =		&sigd_dev_ops,
	.type =		"sig",
	.number =	999,
	.lock =		__SPIN_LOCK_UNLOCKED(sigd_dev.lock)
};

int sigd_attach(struct atm_vcc *vcc)
{
	if (sigd)
		return -EADDRINUSE;
	pr_debug("\n");
	sigd = vcc;
	vcc->dev = &sigd_dev;
	vcc_insert_socket(sk_atm(vcc));
	set_bit(ATM_VF_META, &vcc->flags);
	set_bit(ATM_VF_READY, &vcc->flags);
	return 0;
}
=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/bluetooth/hci_request.c')</div><table summary='diffstat' class='diffstat'>