Jetpack/laird/backport/compat/backport-3.19.c

166 lines
4.6 KiB
C

/*
* Copyright (c) 2014 Hauke Mehrtens <hauke@hauke-m.de>
*
* Backport functionality introduced in Linux 3.19.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/wait.h>
#include <linux/sched.h>
#include <linux/kthread.h>
#include <linux/export.h>
#include <linux/net.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/debugfs.h>
#if LINUX_VERSION_IS_LESS(3,18,12)
static inline bool is_kthread_should_stop(void)
{
return (current->flags & PF_KTHREAD) && kthread_should_stop();
}
/*
* DEFINE_WAIT_FUNC(wait, woken_wake_func);
*
* add_wait_queue(&wq, &wait);
* for (;;) {
* if (condition)
* break;
*
* p->state = mode; condition = true;
* smp_mb(); // A smp_wmb(); // C
* if (!wait->flags & WQ_FLAG_WOKEN) wait->flags |= WQ_FLAG_WOKEN;
* schedule() try_to_wake_up();
* p->state = TASK_RUNNING; ~~~~~~~~~~~~~~~~~~
* wait->flags &= ~WQ_FLAG_WOKEN; condition = true;
* smp_mb() // B smp_wmb(); // C
* wait->flags |= WQ_FLAG_WOKEN;
* }
* remove_wait_queue(&wq, &wait);
*
*/
long wait_woken(wait_queue_t *wait, unsigned mode, long timeout)
{
set_current_state(mode); /* A */
/*
* The above implies an smp_mb(), which matches with the smp_wmb() from
* woken_wake_function() such that if we observe WQ_FLAG_WOKEN we must
* also observe all state before the wakeup.
*/
if (!(wait->flags & WQ_FLAG_WOKEN) && !is_kthread_should_stop())
timeout = schedule_timeout(timeout);
__set_current_state(TASK_RUNNING);
/*
* The below implies an smp_mb(), it too pairs with the smp_wmb() from
* woken_wake_function() such that we must either observe the wait
* condition being true _OR_ WQ_FLAG_WOKEN such that we will not miss
* an event.
*/
set_mb(wait->flags, wait->flags & ~WQ_FLAG_WOKEN); /* B */
return timeout;
}
EXPORT_SYMBOL(wait_woken);
int woken_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key)
{
/*
* Although this function is called under waitqueue lock, LOCK
* doesn't imply write barrier and the users expects write
* barrier semantics on wakeup functions. The following
* smp_wmb() is equivalent to smp_wmb() in try_to_wake_up()
* and is paired with set_mb() in wait_woken().
*/
smp_wmb(); /* C */
wait->flags |= WQ_FLAG_WOKEN;
return default_wake_function(wait, mode, sync, key);
}
EXPORT_SYMBOL(woken_wake_function);
#endif
static u8 netdev_rss_key[NETDEV_RSS_KEY_LEN];
void netdev_rss_key_fill(void *buffer, size_t len)
{
BUG_ON(len > sizeof(netdev_rss_key));
#ifdef __BACKPORT_NET_GET_RANDOM_ONCE
net_get_random_once(netdev_rss_key, sizeof(netdev_rss_key));
memcpy(buffer, netdev_rss_key, len);
#else
get_random_bytes(buffer, len);
#endif
}
EXPORT_SYMBOL_GPL(netdev_rss_key_fill);
#if defined(CONFIG_DEBUG_FS)
struct debugfs_devm_entry {
int (*read)(struct seq_file *seq, void *data);
struct device *dev;
};
static int debugfs_devm_entry_open(struct inode *inode, struct file *f)
{
struct debugfs_devm_entry *entry = inode->i_private;
return single_open(f, entry->read, entry->dev);
}
static const struct file_operations debugfs_devm_entry_ops = {
.owner = THIS_MODULE,
.open = debugfs_devm_entry_open,
.release = single_release,
.read = seq_read,
.llseek = seq_lseek
};
/**
* debugfs_create_devm_seqfile - create a debugfs file that is bound to device.
*
* @dev: device related to this debugfs file.
* @name: name of the debugfs file.
* @parent: a pointer to the parent dentry for this file. This should be a
* directory dentry if set. If this parameter is %NULL, then the
* file will be created in the root of the debugfs filesystem.
* @read_fn: function pointer called to print the seq_file content.
*/
struct dentry *debugfs_create_devm_seqfile(struct device *dev, const char *name,
struct dentry *parent,
int (*read_fn)(struct seq_file *s,
void *data))
{
struct debugfs_devm_entry *entry;
if (IS_ERR(parent))
return ERR_PTR(-ENOENT);
entry = devm_kzalloc(dev, sizeof(*entry), GFP_KERNEL);
if (!entry)
return ERR_PTR(-ENOMEM);
entry->read = read_fn;
entry->dev = dev;
return debugfs_create_file(name, S_IRUGO, parent, entry,
&debugfs_devm_entry_ops);
}
EXPORT_SYMBOL_GPL(debugfs_create_devm_seqfile);
#endif /* CONFIG_DEBUG_FS */
int skb_ensure_writable(struct sk_buff *skb, int write_len)
{
if (!pskb_may_pull(skb, write_len))
return -ENOMEM;
if (!skb_cloned(skb) || skb_clone_writable(skb, write_len))
return 0;
return pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
}
EXPORT_SYMBOL_GPL(skb_ensure_writable);