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-/*
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- * linux/include/linux/relayfs_fs.h
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- *
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- * Copyright (C) 2002, 2003 - Tom Zanussi (zanussi@us.ibm.com), IBM Corp
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- * Copyright (C) 1999, 2000, 2001, 2002 - Karim Yaghmour (karim@opersys.com)
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- *
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- * RelayFS definitions and declarations
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- */
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-
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-#ifndef _LINUX_RELAYFS_FS_H
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-#define _LINUX_RELAYFS_FS_H
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-
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-#include <linux/config.h>
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-#include <linux/types.h>
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-#include <linux/sched.h>
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-#include <linux/wait.h>
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-#include <linux/list.h>
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-#include <linux/fs.h>
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-#include <linux/poll.h>
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-#include <linux/kref.h>
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-
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-/*
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- * Tracks changes to rchan/rchan_buf structs
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- */
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-#define RELAYFS_CHANNEL_VERSION 6
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-
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-/*
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- * Per-cpu relay channel buffer
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- */
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-struct rchan_buf
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-{
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- void *start; /* start of channel buffer */
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- void *data; /* start of current sub-buffer */
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- size_t offset; /* current offset into sub-buffer */
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- size_t subbufs_produced; /* count of sub-buffers produced */
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- size_t subbufs_consumed; /* count of sub-buffers consumed */
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- struct rchan *chan; /* associated channel */
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- wait_queue_head_t read_wait; /* reader wait queue */
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- struct work_struct wake_readers; /* reader wake-up work struct */
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- struct dentry *dentry; /* channel file dentry */
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- struct kref kref; /* channel buffer refcount */
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- struct page **page_array; /* array of current buffer pages */
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- unsigned int page_count; /* number of current buffer pages */
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- unsigned int finalized; /* buffer has been finalized */
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- size_t *padding; /* padding counts per sub-buffer */
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- size_t prev_padding; /* temporary variable */
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- size_t bytes_consumed; /* bytes consumed in cur read subbuf */
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- unsigned int cpu; /* this buf's cpu */
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-} ____cacheline_aligned;
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-
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-/*
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- * Relay channel data structure
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- */
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-struct rchan
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-{
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- u32 version; /* the version of this struct */
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- size_t subbuf_size; /* sub-buffer size */
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- size_t n_subbufs; /* number of sub-buffers per buffer */
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- size_t alloc_size; /* total buffer size allocated */
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- struct rchan_callbacks *cb; /* client callbacks */
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- struct kref kref; /* channel refcount */
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- void *private_data; /* for user-defined data */
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- size_t last_toobig; /* tried to log event > subbuf size */
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- struct rchan_buf *buf[NR_CPUS]; /* per-cpu channel buffers */
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-};
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-
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-/*
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- * Relay channel client callbacks
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- */
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-struct rchan_callbacks
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-{
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- /*
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- * subbuf_start - called on buffer-switch to a new sub-buffer
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- * @buf: the channel buffer containing the new sub-buffer
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- * @subbuf: the start of the new sub-buffer
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- * @prev_subbuf: the start of the previous sub-buffer
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- * @prev_padding: unused space at the end of previous sub-buffer
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- *
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- * The client should return 1 to continue logging, 0 to stop
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- * logging.
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- *
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- * NOTE: subbuf_start will also be invoked when the buffer is
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- * created, so that the first sub-buffer can be initialized
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- * if necessary. In this case, prev_subbuf will be NULL.
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- *
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- * NOTE: the client can reserve bytes at the beginning of the new
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- * sub-buffer by calling subbuf_start_reserve() in this callback.
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- */
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- int (*subbuf_start) (struct rchan_buf *buf,
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- void *subbuf,
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- void *prev_subbuf,
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- size_t prev_padding);
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-
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- /*
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- * buf_mapped - relayfs buffer mmap notification
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- * @buf: the channel buffer
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- * @filp: relayfs file pointer
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- *
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- * Called when a relayfs file is successfully mmapped
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- */
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- void (*buf_mapped)(struct rchan_buf *buf,
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- struct file *filp);
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-
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- /*
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- * buf_unmapped - relayfs buffer unmap notification
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- * @buf: the channel buffer
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- * @filp: relayfs file pointer
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- *
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- * Called when a relayfs file is successfully unmapped
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- */
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- void (*buf_unmapped)(struct rchan_buf *buf,
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- struct file *filp);
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- /*
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- * create_buf_file - create file to represent a relayfs channel buffer
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- * @filename: the name of the file to create
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- * @parent: the parent of the file to create
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- * @mode: the mode of the file to create
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- * @buf: the channel buffer
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- * @is_global: outparam - set non-zero if the buffer should be global
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- *
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- * Called during relay_open(), once for each per-cpu buffer,
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- * to allow the client to create a file to be used to
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- * represent the corresponding channel buffer. If the file is
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- * created outside of relayfs, the parent must also exist in
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- * that filesystem.
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- *
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- * The callback should return the dentry of the file created
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- * to represent the relay buffer.
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- *
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- * Setting the is_global outparam to a non-zero value will
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- * cause relay_open() to create a single global buffer rather
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- * than the default set of per-cpu buffers.
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- *
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- * See Documentation/filesystems/relayfs.txt for more info.
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- */
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- struct dentry *(*create_buf_file)(const char *filename,
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- struct dentry *parent,
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- int mode,
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- struct rchan_buf *buf,
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- int *is_global);
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-
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- /*
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- * remove_buf_file - remove file representing a relayfs channel buffer
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- * @dentry: the dentry of the file to remove
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- *
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- * Called during relay_close(), once for each per-cpu buffer,
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- * to allow the client to remove a file used to represent a
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- * channel buffer.
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- *
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- * The callback should return 0 if successful, negative if not.
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- */
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- int (*remove_buf_file)(struct dentry *dentry);
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-};
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-
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-/*
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- * relayfs kernel API, fs/relayfs/relay.c
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- */
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-
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-struct rchan *relay_open(const char *base_filename,
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- struct dentry *parent,
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- size_t subbuf_size,
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- size_t n_subbufs,
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- struct rchan_callbacks *cb);
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-extern void relay_close(struct rchan *chan);
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-extern void relay_flush(struct rchan *chan);
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-extern void relay_subbufs_consumed(struct rchan *chan,
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- unsigned int cpu,
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- size_t consumed);
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-extern void relay_reset(struct rchan *chan);
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-extern int relay_buf_full(struct rchan_buf *buf);
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-
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-extern size_t relay_switch_subbuf(struct rchan_buf *buf,
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- size_t length);
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-extern struct dentry *relayfs_create_dir(const char *name,
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- struct dentry *parent);
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-extern int relayfs_remove_dir(struct dentry *dentry);
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-extern struct dentry *relayfs_create_file(const char *name,
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- struct dentry *parent,
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- int mode,
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- struct file_operations *fops,
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- void *data);
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-extern int relayfs_remove_file(struct dentry *dentry);
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-
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-/**
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- * relay_write - write data into the channel
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- * @chan: relay channel
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- * @data: data to be written
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- * @length: number of bytes to write
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- *
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- * Writes data into the current cpu's channel buffer.
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- *
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- * Protects the buffer by disabling interrupts. Use this
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- * if you might be logging from interrupt context. Try
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- * __relay_write() if you know you won't be logging from
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- * interrupt context.
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- */
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-static inline void relay_write(struct rchan *chan,
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- const void *data,
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- size_t length)
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-{
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- unsigned long flags;
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- struct rchan_buf *buf;
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-
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- local_irq_save(flags);
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- buf = chan->buf[smp_processor_id()];
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- if (unlikely(buf->offset + length > chan->subbuf_size))
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- length = relay_switch_subbuf(buf, length);
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- memcpy(buf->data + buf->offset, data, length);
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- buf->offset += length;
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- local_irq_restore(flags);
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-}
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-
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-/**
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- * __relay_write - write data into the channel
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- * @chan: relay channel
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- * @data: data to be written
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- * @length: number of bytes to write
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- *
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- * Writes data into the current cpu's channel buffer.
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- *
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- * Protects the buffer by disabling preemption. Use
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- * relay_write() if you might be logging from interrupt
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- * context.
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- */
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-static inline void __relay_write(struct rchan *chan,
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- const void *data,
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- size_t length)
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-{
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- struct rchan_buf *buf;
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-
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- buf = chan->buf[get_cpu()];
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- if (unlikely(buf->offset + length > buf->chan->subbuf_size))
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- length = relay_switch_subbuf(buf, length);
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- memcpy(buf->data + buf->offset, data, length);
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- buf->offset += length;
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- put_cpu();
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-}
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-
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-/**
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- * relay_reserve - reserve slot in channel buffer
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- * @chan: relay channel
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- * @length: number of bytes to reserve
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- *
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- * Returns pointer to reserved slot, NULL if full.
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- *
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- * Reserves a slot in the current cpu's channel buffer.
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- * Does not protect the buffer at all - caller must provide
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- * appropriate synchronization.
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- */
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-static inline void *relay_reserve(struct rchan *chan, size_t length)
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-{
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- void *reserved;
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- struct rchan_buf *buf = chan->buf[smp_processor_id()];
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-
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- if (unlikely(buf->offset + length > buf->chan->subbuf_size)) {
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- length = relay_switch_subbuf(buf, length);
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- if (!length)
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- return NULL;
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- }
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- reserved = buf->data + buf->offset;
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- buf->offset += length;
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-
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- return reserved;
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-}
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-
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-/**
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- * subbuf_start_reserve - reserve bytes at the start of a sub-buffer
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- * @buf: relay channel buffer
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- * @length: number of bytes to reserve
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- *
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- * Helper function used to reserve bytes at the beginning of
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- * a sub-buffer in the subbuf_start() callback.
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- */
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-static inline void subbuf_start_reserve(struct rchan_buf *buf,
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- size_t length)
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-{
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- BUG_ON(length >= buf->chan->subbuf_size - 1);
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- buf->offset = length;
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-}
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-
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-/*
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- * exported relay file operations, fs/relayfs/inode.c
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- */
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-extern struct file_operations relay_file_operations;
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-
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-#endif /* _LINUX_RELAYFS_FS_H */
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-
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