/*
 * Copyright (C) ST-Ericsson AB 2010
 * Author:	Sjur Brendeland
 * License terms: GNU General Public License (GPL) version 2
 */

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

#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/pkt_sched.h>
#include <net/caif/caif_layer.h>
#include <net/caif/cfsrvl.h>
#include <net/caif/cfpkt.h>
#include <net/caif/caif_dev.h>

#define SRVL_CTRL_PKT_SIZE 1
#define SRVL_FLOW_OFF 0x81
#define SRVL_FLOW_ON  0x80
#define SRVL_SET_PIN  0x82
#define SRVL_CTRL_PKT_SIZE 1

#define container_obj(layr) container_of(layr, struct cfsrvl, layer)

static void cfservl_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
			    int phyid)
{
	struct cfsrvl *service = container_obj(layr);

	if (layr->up == NULL || layr->up->ctrlcmd == NULL)
		return;

	switch (ctrl) {
	case CAIF_CTRLCMD_INIT_RSP:
		service->open = true;
		layr->up->ctrlcmd(layr->up, ctrl, phyid);
		break;
	case CAIF_CTRLCMD_DEINIT_RSP:
	case CAIF_CTRLCMD_INIT_FAIL_RSP:
		service->open = false;
		layr->up->ctrlcmd(layr->up, ctrl, phyid);
		break;
	case _CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND:
		if (phyid != service->dev_info.id)
			break;
		if (service->modem_flow_on)
			layr->up->ctrlcmd(layr->up,
					  CAIF_CTRLCMD_FLOW_OFF_IND, phyid);
		service->phy_flow_on = false;
		break;
	case _CAIF_CTRLCMD_PHYIF_FLOW_ON_IND:
		if (phyid != service->dev_info.id)
			return;
		if (service->modem_flow_on) {
			layr->up->ctrlcmd(layr->up,
					   CAIF_CTRLCMD_FLOW_ON_IND,
					   phyid);
		}
		service->phy_flow_on = true;
		break;
	case CAIF_CTRLCMD_FLOW_OFF_IND:
		if (service->phy_flow_on) {
			layr->up->ctrlcmd(layr->up,
					  CAIF_CTRLCMD_FLOW_OFF_IND, phyid);
		}
		service->modem_flow_on = false;
		break;
	case CAIF_CTRLCMD_FLOW_ON_IND:
		if (service->phy_flow_on) {
			layr->up->ctrlcmd(layr->up,
					  CAIF_CTRLCMD_FLOW_ON_IND, phyid);
		}
		service->modem_flow_on = true;
		break;
	case _CAIF_CTRLCMD_PHYIF_DOWN_IND:
		/* In case interface is down, let's fake a remove shutdown */
		layr->up->ctrlcmd(layr->up,
				CAIF_CTRLCMD_REMOTE_SHUTDOWN_IND, phyid);
		break;
	case CAIF_CTRLCMD_REMOTE_SHUTDOWN_IND:
		layr->up->ctrlcmd(layr->up, ctrl, phyid);
		break;
	default:
		pr_warn("Unexpected ctrl in cfsrvl (%d)\n", ctrl);
		/* We have both modem and phy flow on, send flow on */
		layr->up->ctrlcmd(layr->up, ctrl, phyid);
		service->phy_flow_on = true;
		break;
	}
}

static int cfservl_modemcmd(struct cflayer *layr, enum caif_modemcmd ctrl)
{
	struct cfsrvl *service = container_obj(layr);

	caif_assert(layr != NULL);
	caif_assert(layr->dn != NULL);
	caif_assert(layr->dn->transmit != NULL);

	if (!service->supports_flowctrl)
		return 0;

	switch (ctrl) {
	case CAIF_MODEMCMD_FLOW_ON_REQ:
		{
			struct cfpkt *pkt;
			struct caif_payload_info *info;
			u8 flow_on = SRVL_FLOW_ON;
			pkt = cfpkt_create(SRVL_CTRL_PKT_SIZE);
			if (!pkt)
				return -ENOMEM;

			if (cfpkt_add_head(pkt, &flow_on, 1) < 0) {
				pr_err("Packet is erroneous!\n");
				cfpkt_destroy(pkt);
				return -EPROTO;
			}
			info = cfpkt_info(pkt);
			info->channel_id = service->layer.id;
			info->hdr_len = 1;
			info->dev_info = &service->dev_info;
			cfpkt_set_prio(pkt, TC_PRIO_CONTROL);
			return layr->dn->transmit(layr->dn, pkt);
		}
	case CAIF_MODEMCMD_FLOW_OFF_REQ:
		{
			struct cfpkt *pkt;
			struct caif_payload_info *info;
			u8 flow_off = SRVL_FLOW_OFF;
			pkt = cfpkt_create(SRVL_CTRL_PKT_SIZE);
			if (!pkt)
				return -ENOMEM;

			if (cfpkt_add_head(pkt, &flow_off, 1) < 0) {
				pr_err("Packet is erroneous!\n");
				cfpkt_destroy(pkt);
				return -EPROTO;
			}
			info = cfpkt_info(pkt);
			info->channel_id = service->layer.id;
			info->hdr_len = 1;
			info->dev_info = &service->dev_info;
			cfpkt_set_prio(pkt, TC_PRIO_CONTROL);
			return layr->dn->transmit(layr->dn, pkt);
		}
	default:
	  break;
	}
	return -EINVAL;
}

static void cfsrvl_release(struct cflayer *layer)
{
	struct cfsrvl *service = container_of(layer, struct cfsrvl, layer);
	kfree(service);
}

void cfsrvl_init(struct cfsrvl *service,
		 u8 channel_id,
		 struct dev_info *dev_info,
		 bool supports_flowctrl)
{
	caif_assert(offsetof(struct cfsrvl, layer) == 0);
	service->open = false;
	service->modem_flow_on = true;
	service->phy_flow_on = true;
	service->layer.id = channel_id;
	service->layer.ctrlcmd = cfservl_ctrlcmd;
	service->layer.modemcmd = cfservl_modemcmd;
	service->dev_info = *dev_info;
	service->supports_flowctrl = supports_flowctrl;
	service->release = cfsrvl_release;
}

bool cfsrvl_ready(struct cfsrvl *service, int *err)
{
	if (!service->open) {
		*err = -ENOTCONN;
		return false;
	}
	return true;
}

u8 cfsrvl_getphyid(struct cflayer *layer)
{
	struct cfsrvl *servl = container_obj(layer);
	return servl->dev_info.id;
}

bool cfsrvl_phyid_match(struct cflayer *layer, int phyid)
{
	struct cfsrvl *servl = container_obj(layer);
	return servl->dev_info.id == phyid;
}

void caif_free_client(struct cflayer *adap_layer)
{
	struct cfsrvl *servl;
	if (adap_layer == NULL || adap_layer->dn == NULL)
		return;
	servl = container_obj(adap_layer->dn);
	servl->release(&servl->layer);
}
EXPORT_SYMBOL(caif_free_client);

void caif_client_register_refcnt(struct cflayer *adapt_layer,
				 void (*hold)(struct cflayer *lyr),
				 void (*put)(struct cflayer *lyr))
{
	struct cfsrvl *service;

	if (WARN_ON(adapt_layer == NULL || adapt_layer->dn == NULL))
		return;
	service = container_of(adapt_layer->dn, struct cfsrvl, layer);
	service->hold = hold;
	service->put = put;
}
EXPORT_SYMBOL(caif_client_register_refcnt);
b62756323c675a44cb1a1f9dbd</a> (<a href='/cgit.cgi/linux/net-next.git/diff/net/l3mdev/l3mdev.c?id=966d2b04e070bc040319aaebfec09e0144dc3341&amp;id2=1b1bc42c1692e9b62756323c675a44cb1a1f9dbd'>diff</a>)</td></tr></table>
<div class='commit-subject'>percpu-refcount: fix reference leak during percpu-atomic transition</div><div class='commit-msg'>percpu_ref_tryget() and percpu_ref_tryget_live() should return
"true" IFF they acquire a reference. But the return value from
atomic_long_inc_not_zero() is a long and may have high bits set,
e.g. PERCPU_COUNT_BIAS, and the return value of the tryget routines
is bool so the reference may actually be acquired but the routines
return "false" which results in a reference leak since the caller
assumes it does not need to do a corresponding percpu_ref_put().

This was seen when performing CPU hotplug during I/O, as hangs in
blk_mq_freeze_queue_wait where percpu_ref_kill (blk_mq_freeze_queue_start)
raced with percpu_ref_tryget (blk_mq_timeout_work).
Sample stack trace:

__switch_to+0x2c0/0x450
__schedule+0x2f8/0x970
schedule+0x48/0xc0
blk_mq_freeze_queue_wait+0x94/0x120
blk_mq_queue_reinit_work+0xb8/0x180
blk_mq_queue_reinit_prepare+0x84/0xa0
cpuhp_invoke_callback+0x17c/0x600
cpuhp_up_callbacks+0x58/0x150
_cpu_up+0xf0/0x1c0
do_cpu_up+0x120/0x150
cpu_subsys_online+0x64/0xe0
device_online+0xb4/0x120
online_store+0xb4/0xc0
dev_attr_store+0x68/0xa0
sysfs_kf_write+0x80/0xb0
kernfs_fop_write+0x17c/0x250
__vfs_write+0x6c/0x1e0
vfs_write+0xd0/0x270
SyS_write+0x6c/0x110
system_call+0x38/0xe0

Examination of the queue showed a single reference (no PERCPU_COUNT_BIAS,
and __PERCPU_REF_DEAD, __PERCPU_REF_ATOMIC set) and no requests.
However, conditions at the time of the race are count of PERCPU_COUNT_BIAS + 0
and __PERCPU_REF_DEAD and __PERCPU_REF_ATOMIC set.

The fix is to make the tryget routines use an actual boolean internally instead
of the atomic long result truncated to a int.

Fixes: e625305b3907 percpu-refcount: make percpu_ref based on longs instead of ints
Link: https://bugzilla.kernel.org/show_bug.cgi?id=190751
Signed-off-by: Douglas Miller &lt;dougmill@linux.vnet.ibm.com&gt;
Reviewed-by: Jens Axboe &lt;axboe@fb.com&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Fixes: e625305b3907 ("percpu-refcount: make percpu_ref based on longs instead of ints")
Cc: stable@vger.kernel.org # v3.18+
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?id=966d2b04e070bc040319aaebfec09e0144dc3341'>Diffstat</a> (limited to 'net/l3mdev/l3mdev.c')</div><table summary='diffstat' class='diffstat'>