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path: root/net/appletalk/dev.c
blob: e4158b8b926d39c725e6fc1b644360e5fe27f965 (plain)
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/*
 * Moved here from drivers/net/net_init.c, which is:
 *	Written 1993,1994,1995 by Donald Becker.
 */

#include <linux/errno.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/if_arp.h>
#include <linux/if_ltalk.h>

static void ltalk_setup(struct net_device *dev)
{
	/* Fill in the fields of the device structure with localtalk-generic values. */

	dev->type		= ARPHRD_LOCALTLK;
	dev->hard_header_len 	= LTALK_HLEN;
	dev->mtu		= LTALK_MTU;
	dev->addr_len		= LTALK_ALEN;
	dev->tx_queue_len	= 10;

	dev->broadcast[0]	= 0xFF;

	dev->flags		= IFF_BROADCAST|IFF_MULTICAST|IFF_NOARP;
}

/**
 * alloc_ltalkdev - Allocates and sets up an localtalk device
 * @sizeof_priv: Size of additional driver-private structure to be allocated
 *	for this localtalk device
 *
 * Fill in the fields of the device structure with localtalk-generic
 * values. Basically does everything except registering the device.
 *
 * Constructs a new net device, complete with a private data area of
 * size @sizeof_priv.  A 32-byte (not bit) alignment is enforced for
 * this private data area.
 */

struct net_device *alloc_ltalkdev(int sizeof_priv)
{
	return alloc_netdev(sizeof_priv, "lt%d", NET_NAME_UNKNOWN,
			    ltalk_setup);
}
EXPORT_SYMBOL(alloc_ltalkdev);
cpu-atomic transition
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 <dougmill@linux.vnet.ibm.com> Reviewed-by: Jens Axboe <axboe@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org> Fixes: e625305b3907 ("percpu-refcount: make percpu_ref based on longs instead of ints") Cc: stable@vger.kernel.org # v3.18+
Diffstat (limited to 'include/uapi/sound/emu10k1.h')