The Linux Kernel API
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# The Linux Kernel API

This documentation is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

For more details see the file COPYING in the source distribution of Linux.

Table of Contents

1. Data Types
  Doubly Linked Lists
2. Basic C Library Functions
  String Conversions
  String Manipulation
  Bit Operations
3. Basic Kernel Library Functions
  Bitmap Operations
  Command-line Parsing
  CRC Functions
  idr/ida Functions
4. Memory Management in Linux
  The Slab Cache
  User Space Memory Access
  More Memory Management Functions
5. Kernel IPC facilities
  IPC utilities
6. FIFO Buffer
  kfifo interface
7. relay interface support
  relay interface
8. Module Support
  Module Loading
  Inter Module support
9. Hardware Interfaces
  Interrupt Handling
  DMA Channels
  Resources Management
  MTRR Handling
  PCI Support Library
  PCI Hotplug Support Library
10. Firmware Interfaces
  DMI Interfaces
  EDD Interfaces
11. Security Framework
  security_init — initializes the security framework
  security_module_enable — Load given security module on boot ?
  securityfs_create_dentry — create a file/dir in the securityfs filesystem
  securityfs_create_file — create a file in the securityfs filesystem
  securityfs_create_dir — create a directory in the securityfs filesystem
  securityfs_remove — removes a file or directory from the securityfs filesystem
12. Audit Interfaces
  audit_log_start — obtain an audit buffer
  audit_log_format — format a message into the audit buffer.
  audit_log_end — end one audit record
  audit_log — Log an audit record
  audit_log_secctx — Converts and logs SELinux context
  audit_alloc — allocate an audit context block for a task
  __audit_free — free a per-task audit context
  __audit_syscall_entry — fill in an audit record at syscall entry
  __audit_syscall_exit — deallocate audit context after a system call
  __audit_reusename — fill out filename with info from existing entry
  __audit_getname — add a name to the list
  __audit_inode — store the inode and device from a lookup
  auditsc_get_stamp — get local copies of audit_context values
  audit_set_loginuid — set current task's audit_context loginuid
  __audit_mq_open — record audit data for a POSIX MQ open
  __audit_mq_sendrecv — record audit data for a POSIX MQ timed send/receive
  __audit_mq_notify — record audit data for a POSIX MQ notify
  __audit_mq_getsetattr — record audit data for a POSIX MQ get/set attribute
  __audit_ipc_obj — record audit data for ipc object
  __audit_ipc_set_perm — record audit data for new ipc permissions
  __audit_socketcall — record audit data for sys_socketcall
  __audit_fd_pair — record audit data for pipe and socketpair
  __audit_sockaddr — record audit data for sys_bind, sys_connect, sys_sendto
  __audit_signal_info — record signal info for shutting down audit subsystem
  __audit_log_bprm_fcaps — store information about a loading bprm and relevant fcaps
  __audit_log_capset — store information about the arguments to the capset syscall
  audit_core_dumps — record information about processes that end abnormally
  audit_rule_change — apply all rules to the specified message type
  audit_list_rules_send — list the audit rules
  parent_len — find the length of the parent portion of a pathname
  audit_compare_dname_path — compare given dentry name with last component in given path. Return of 0 indicates a match.
13. Accounting Framework
  sys_acct — enable/disable process accounting
  acct_collect — collect accounting information into pacct_struct
  acct_process —
14. Block Devices
  blk_delay_queue — restart queueing after defined interval
  blk_start_queue_async — asynchronously restart a previously stopped queue
  blk_start_queue — restart a previously stopped queue
  blk_stop_queue — stop a queue
  blk_sync_queue — cancel any pending callbacks on a queue
  __blk_run_queue_uncond — run a queue whether or not it has been stopped
  __blk_run_queue — run a single device queue
  blk_run_queue_async — run a single device queue in workqueue context
  blk_run_queue — run a single device queue
  blk_queue_bypass_start — enter queue bypass mode
  blk_queue_bypass_end — leave queue bypass mode
  blk_cleanup_queue — shutdown a request queue
  blk_init_queue — prepare a request queue for use with a block device
  blk_make_request — given a bio, allocate a corresponding struct request.
  blk_rq_set_block_pc — initialize a request to type BLOCK_PC
  blk_requeue_request — put a request back on queue
  part_round_stats — Round off the performance stats on a struct disk_stats.
  blk_add_request_payload — add a payload to a request
  generic_make_request — hand a buffer to its device driver for I/O
  submit_bio — submit a bio to the block device layer for I/O
  blk_insert_cloned_request — Helper for stacking drivers to submit a request
  blk_rq_err_bytes — determine number of bytes till the next failure boundary
  blk_peek_request — peek at the top of a request queue
  blk_start_request — start request processing on the driver
  blk_fetch_request — fetch a request from a request queue
  blk_update_request — Special helper function for request stacking drivers
  blk_unprep_request — unprepare a request
  blk_end_request — Helper function for drivers to complete the request.
  blk_end_request_all — Helper function for drives to finish the request.
  blk_end_request_cur — Helper function to finish the current request chunk.
  blk_end_request_err — Finish a request till the next failure boundary.
  __blk_end_request — Helper function for drivers to complete the request.
  __blk_end_request_all — Helper function for drives to finish the request.
  __blk_end_request_cur — Helper function to finish the current request chunk.
  __blk_end_request_err — Finish a request till the next failure boundary.
  rq_flush_dcache_pages — Helper function to flush all pages in a request
  blk_lld_busy — Check if underlying low-level drivers of a device are busy
  blk_rq_unprep_clone — Helper function to free all bios in a cloned request
  blk_rq_prep_clone — Helper function to setup clone request
  blk_start_plug — initialize blk_plug and track it inside the task_struct
  blk_pm_runtime_init — Block layer runtime PM initialization routine
  blk_pre_runtime_suspend — Pre runtime suspend check
  blk_post_runtime_suspend — Post runtime suspend processing
  blk_pre_runtime_resume — Pre runtime resume processing
  blk_post_runtime_resume — Post runtime resume processing
  __blk_drain_queue — drain requests from request_queue
  rq_ioc — determine io_context for request allocation
  __get_request — get a free request
  get_request — get a free request
  blk_attempt_plug_merge — try to merge with `current`'s plugged list
  blk_cloned_rq_check_limits — Helper function to check a cloned request for new the queue limits
  blk_end_bidi_request — Complete a bidi request
  __blk_end_bidi_request — Complete a bidi request with queue lock held
  blk_rq_map_user_iov — map user data to a request, for REQ_TYPE_BLOCK_PC usage
  blk_rq_unmap_user — unmap a request with user data
  blk_rq_map_kern — map kernel data to a request, for REQ_TYPE_BLOCK_PC usage
  blk_release_queue — release a struct request_queue when it is no longer needed
  blk_queue_prep_rq — set a prepare_request function for queue
  blk_queue_unprep_rq — set an unprepare_request function for queue
  blk_set_default_limits — reset limits to default values
  blk_set_stacking_limits — set default limits for stacking devices
  blk_queue_make_request — define an alternate make_request function for a device
  blk_queue_bounce_limit — set bounce buffer limit for queue
  blk_queue_max_hw_sectors — set max sectors for a request for this queue
  blk_queue_chunk_sectors — set size of the chunk for this queue
  blk_queue_max_discard_sectors — set max sectors for a single discard
  blk_queue_max_write_same_sectors — set max sectors for a single write same
  blk_queue_max_segments — set max hw segments for a request for this queue
  blk_queue_max_segment_size — set max segment size for blk_rq_map_sg
  blk_queue_logical_block_size — set logical block size for the queue
  blk_queue_physical_block_size — set physical block size for the queue
  blk_queue_alignment_offset — set physical block alignment offset
  blk_limits_io_min — set minimum request size for a device
  blk_queue_io_min — set minimum request size for the queue
  blk_limits_io_opt — set optimal request size for a device
  blk_queue_io_opt — set optimal request size for the queue
  blk_queue_stack_limits — inherit underlying queue limits for stacked drivers
  blk_stack_limits — adjust queue_limits for stacked devices
  bdev_stack_limits — adjust queue limits for stacked drivers
  disk_stack_limits — adjust queue limits for stacked drivers
  blk_queue_dma_pad — set pad mask
  blk_queue_update_dma_pad — update pad mask
  blk_queue_dma_drain — Set up a drain buffer for excess dma.
  blk_queue_segment_boundary — set boundary rules for segment merging
  blk_queue_virt_boundary — set boundary rules for bio merging
  blk_queue_dma_alignment — set dma length and memory alignment
  blk_queue_update_dma_alignment — update dma length and memory alignment
  blk_queue_flush — configure queue's cache flush capability
  blk_execute_rq_nowait — insert a request into queue for execution
  blk_execute_rq — insert a request into queue for execution
  blkdev_issue_flush — queue a flush
  blkdev_issue_discard — queue a discard
  blkdev_issue_write_same — queue a write same operation
  blkdev_issue_zeroout — zero-fill a block range
  blk_queue_find_tag — find a request by its tag and queue
  blk_free_tags — release a given set of tag maintenance info
  blk_queue_free_tags — release tag maintenance info
  blk_init_tags — initialize the tag info for an external tag map
  blk_queue_init_tags — initialize the queue tag info
  blk_queue_resize_tags — change the queueing depth
  blk_queue_end_tag — end tag operations for a request
  blk_queue_start_tag — find a free tag and assign it
  blk_queue_invalidate_tags — invalidate all pending tags
  __blk_queue_free_tags — release tag maintenance info
  blk_rq_count_integrity_sg — Count number of integrity scatterlist elements
  blk_rq_map_integrity_sg — Map integrity metadata into a scatterlist
  blk_integrity_compare — Compare integrity profile of two disks
  blk_integrity_register — Register a gendisk as being integrity-capable
  blk_integrity_unregister — Unregister block integrity profile
  blk_trace_ioctl — handle the ioctls associated with tracing
  blk_trace_shutdown — stop and cleanup trace structures
  blk_add_trace_rq — Add a trace for a request oriented action
  blk_add_trace_bio — Add a trace for a bio oriented action
  blk_add_trace_bio_remap — Add a trace for a bio-remap operation
  blk_add_trace_rq_remap — Add a trace for a request-remap operation
  blk_mangle_minor — scatter minor numbers apart
  blk_alloc_devt — allocate a dev_t for a partition
  blk_free_devt — free a dev_t
  disk_replace_part_tbl — replace disk->part_tbl in RCU-safe way
  disk_expand_part_tbl — expand disk->part_tbl
  disk_block_events — block and flush disk event checking
  disk_unblock_events — unblock disk event checking
  disk_flush_events — schedule immediate event checking and flushing
  disk_clear_events — synchronously check, clear and return pending events
  disk_get_part — get partition
  disk_part_iter_init — initialize partition iterator
  disk_part_iter_next — proceed iterator to the next partition and return it
  disk_part_iter_exit — finish up partition iteration
  disk_map_sector_rcu — map sector to partition
  register_blkdev — register a new block device
  add_disk — add partitioning information to kernel list
  get_gendisk — get partitioning information for a given device
  bdget_disk — do `bdget` by gendisk and partition number
15. Char devices
  register_chrdev_region — register a range of device numbers
  alloc_chrdev_region — register a range of char device numbers
  __register_chrdev — create and register a cdev occupying a range of minors
  unregister_chrdev_region — unregister a range of device numbers
  __unregister_chrdev — unregister and destroy a cdev
  cdev_add — add a char device to the system
  cdev_del — remove a cdev from the system
  cdev_alloc — allocate a cdev structure
  cdev_init — initialize a cdev structure
16. Miscellaneous Devices
  misc_register — register a miscellaneous device
  misc_deregister — unregister a miscellaneous device
17. Clock Framework
  struct clk_notifier — associate a clk with a notifier
  struct clk_notifier_data — rate data to pass to the notifier callback
  clk_notifier_register — change notifier callback
  clk_notifier_unregister — change notifier callback
  clk_get_accuracy — obtain the clock accuracy in ppb (parts per billion) for a clock source.
  clk_set_phase — adjust the phase shift of a clock signal
  clk_get_phase — return the phase shift of a clock signal
  clk_is_match — check if two clk's point to the same hardware clock
  clk_prepare — prepare a clock source
  clk_unprepare — undo preparation of a clock source
  clk_get — lookup and obtain a reference to a clock producer.
  devm_clk_get — lookup and obtain a managed reference to a clock producer.
  clk_enable — inform the system when the clock source should be running.
  clk_disable — inform the system when the clock source is no longer required.
  clk_get_rate — obtain the current clock rate (in Hz) for a clock source. This is only valid once the clock source has been enabled.
  clk_put — "free" the clock source
  devm_clk_put — "free" a managed clock source
  clk_round_rate — adjust a rate to the exact rate a clock can provide
  clk_set_rate — set the clock rate for a clock source
  clk_has_parent — check if a clock is a possible parent for another
  clk_set_rate_range — set a rate range for a clock source
  clk_set_min_rate — set a minimum clock rate for a clock source
  clk_set_max_rate — set a maximum clock rate for a clock source
  clk_set_parent — set the parent clock source for this clock
  clk_get_parent — get the parent clock source for this clock
  clk_get_sys — get a clock based upon the device name

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