diff options
Diffstat (limited to 'compat/backport-3.19.c')
| -rw-r--r-- | compat/backport-3.19.c | 165 |
1 files changed, 165 insertions, 0 deletions
diff --git a/compat/backport-3.19.c b/compat/backport-3.19.c new file mode 100644 index 0000000..019644d --- /dev/null +++ b/compat/backport-3.19.c @@ -0,0 +1,165 @@ +/* + * 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); |