diff options
Diffstat (limited to 'include/linux/pipe_fs_i.h')
| -rw-r--r-- | include/linux/pipe_fs_i.h | 301 |
1 files changed, 237 insertions, 64 deletions
diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h index b8809fef61f5..7f6a92ac9704 100644 --- a/include/linux/pipe_fs_i.h +++ b/include/linux/pipe_fs_i.h @@ -1,3 +1,4 @@ +/* SPDX-License-Identifier: GPL-2.0 */ #ifndef _LINUX_PIPE_FS_I_H #define _LINUX_PIPE_FS_I_H @@ -7,6 +8,11 @@ #define PIPE_BUF_FLAG_ATOMIC 0x02 /* was atomically mapped */ #define PIPE_BUF_FLAG_GIFT 0x04 /* page is a gift */ #define PIPE_BUF_FLAG_PACKET 0x08 /* read() as a packet */ +#define PIPE_BUF_FLAG_CAN_MERGE 0x10 /* can merge buffers */ +#define PIPE_BUF_FLAG_WHOLE 0x20 /* read() must return entire buffer or error */ +#ifdef CONFIG_WATCH_QUEUE +#define PIPE_BUF_FLAG_LOSS 0x40 /* Message loss happened after this buffer */ +#endif /** * struct pipe_buffer - a linux kernel pipe buffer @@ -25,86 +31,101 @@ struct pipe_buffer { unsigned long private; }; +/* + * Really only alpha needs 32-bit fields, but + * might as well do it for 64-bit architectures + * since that's what we've historically done, + * and it makes 'head_tail' always be a simple + * 'unsigned long'. + */ +#ifdef CONFIG_64BIT +typedef unsigned int pipe_index_t; +#else +typedef unsigned short pipe_index_t; +#endif + +/** + * struct pipe_index - pipe indeces + * @head: The point of buffer production + * @tail: The point of buffer consumption + * @head_tail: unsigned long union of @head and @tail + */ +union pipe_index { + unsigned long head_tail; + struct { + pipe_index_t head; + pipe_index_t tail; + }; +}; + /** * struct pipe_inode_info - a linux kernel pipe * @mutex: mutex protecting the whole thing - * @wait: reader/writer wait point in case of empty/full pipe - * @nrbufs: the number of non-empty pipe buffers in this pipe - * @buffers: total number of buffers (should be a power of 2) - * @curbuf: the current pipe buffer entry + * @rd_wait: reader wait point in case of empty pipe + * @wr_wait: writer wait point in case of full pipe + * @pipe_index: the pipe indeces + * @note_loss: The next read() should insert a data-lost message + * @max_usage: The maximum number of slots that may be used in the ring + * @ring_size: total number of buffers (should be a power of 2) + * @nr_accounted: The amount this pipe accounts for in user->pipe_bufs * @tmp_page: cached released page * @readers: number of current readers of this pipe * @writers: number of current writers of this pipe - * @files: number of struct file refering this pipe (protected by ->i_lock) - * @waiting_writers: number of writers blocked waiting for room + * @files: number of struct file referring this pipe (protected by ->i_lock) * @r_counter: reader counter * @w_counter: writer counter + * @poll_usage: is this pipe used for epoll, which has crazy wakeups? * @fasync_readers: reader side fasync * @fasync_writers: writer side fasync * @bufs: the circular array of pipe buffers + * @user: the user who created this pipe + * @watch_queue: If this pipe is a watch_queue, this is the stuff for that **/ struct pipe_inode_info { struct mutex mutex; - wait_queue_head_t wait; - unsigned int nrbufs, curbuf, buffers; + wait_queue_head_t rd_wait, wr_wait; + + union pipe_index; + + unsigned int max_usage; + unsigned int ring_size; + unsigned int nr_accounted; unsigned int readers; unsigned int writers; unsigned int files; - unsigned int waiting_writers; unsigned int r_counter; unsigned int w_counter; - struct page *tmp_page; + bool poll_usage; +#ifdef CONFIG_WATCH_QUEUE + bool note_loss; +#endif + struct page *tmp_page[2]; struct fasync_struct *fasync_readers; struct fasync_struct *fasync_writers; struct pipe_buffer *bufs; + struct user_struct *user; +#ifdef CONFIG_WATCH_QUEUE + struct watch_queue *watch_queue; +#endif }; /* * Note on the nesting of these functions: * * ->confirm() - * ->steal() - * ... - * ->map() - * ... - * ->unmap() + * ->try_steal() * - * That is, ->map() must be called on a confirmed buffer, - * same goes for ->steal(). See below for the meaning of each - * operation. Also see kerneldoc in fs/pipe.c for the pipe - * and generic variants of these hooks. + * That is, ->try_steal() must be called on a confirmed buffer. See below for + * the meaning of each operation. Also see the kerneldoc in fs/pipe.c for the + * pipe and generic variants of these hooks. */ struct pipe_buf_operations { /* - * This is set to 1, if the generic pipe read/write may coalesce - * data into an existing buffer. If this is set to 0, a new pipe - * page segment is always used for new data. - */ - int can_merge; - - /* - * ->map() returns a virtual address mapping of the pipe buffer. - * The last integer flag reflects whether this should be an atomic - * mapping or not. The atomic map is faster, however you can't take - * page faults before calling ->unmap() again. So if you need to eg - * access user data through copy_to/from_user(), then you must get - * a non-atomic map. ->map() uses the kmap_atomic slot for - * atomic maps, you have to be careful if mapping another page as - * source or destination for a copy. - */ - void * (*map)(struct pipe_inode_info *, struct pipe_buffer *, int); - - /* - * Undoes ->map(), finishes the virtual mapping of the pipe buffer. - */ - void (*unmap)(struct pipe_inode_info *, struct pipe_buffer *, void *); - - /* * ->confirm() verifies that the data in the pipe buffer is there * and that the contents are good. If the pages in the pipe belong * to a file system, we may need to wait for IO completion in this * hook. Returns 0 for good, or a negative error value in case of - * error. + * error. If not present all pages are considered good. */ int (*confirm)(struct pipe_inode_info *, struct pipe_buffer *); @@ -116,20 +137,168 @@ struct pipe_buf_operations { /* * Attempt to take ownership of the pipe buffer and its contents. - * ->steal() returns 0 for success, in which case the contents - * of the pipe (the buf->page) is locked and now completely owned - * by the caller. The page may then be transferred to a different - * mapping, the most often used case is insertion into different - * file address space cache. + * ->try_steal() returns %true for success, in which case the contents + * of the pipe (the buf->page) is locked and now completely owned by the + * caller. The page may then be transferred to a different mapping, the + * most often used case is insertion into different file address space + * cache. */ - int (*steal)(struct pipe_inode_info *, struct pipe_buffer *); + bool (*try_steal)(struct pipe_inode_info *, struct pipe_buffer *); /* * Get a reference to the pipe buffer. */ - void (*get)(struct pipe_inode_info *, struct pipe_buffer *); + bool (*get)(struct pipe_inode_info *, struct pipe_buffer *); }; +/** + * pipe_has_watch_queue - Check whether the pipe is a watch_queue, + * i.e. it was created with O_NOTIFICATION_PIPE + * @pipe: The pipe to check + * + * Return: true if pipe is a watch queue, false otherwise. + */ +static inline bool pipe_has_watch_queue(const struct pipe_inode_info *pipe) +{ +#ifdef CONFIG_WATCH_QUEUE + return pipe->watch_queue != NULL; +#else + return false; +#endif +} + +/** + * pipe_occupancy - Return number of slots used in the pipe + * @head: The pipe ring head pointer + * @tail: The pipe ring tail pointer + */ +static inline unsigned int pipe_occupancy(unsigned int head, unsigned int tail) +{ + return (pipe_index_t)(head - tail); +} + +/** + * pipe_empty - Return true if the pipe is empty + * @head: The pipe ring head pointer + * @tail: The pipe ring tail pointer + */ +static inline bool pipe_empty(unsigned int head, unsigned int tail) +{ + return !pipe_occupancy(head, tail); +} + +/** + * pipe_full - Return true if the pipe is full + * @head: The pipe ring head pointer + * @tail: The pipe ring tail pointer + * @limit: The maximum amount of slots available. + */ +static inline bool pipe_full(unsigned int head, unsigned int tail, + unsigned int limit) +{ + return pipe_occupancy(head, tail) >= limit; +} + +/** + * pipe_is_full - Return true if the pipe is full + * @pipe: the pipe + */ +static inline bool pipe_is_full(const struct pipe_inode_info *pipe) +{ + return pipe_full(pipe->head, pipe->tail, pipe->max_usage); +} + +/** + * pipe_is_empty - Return true if the pipe is empty + * @pipe: the pipe + */ +static inline bool pipe_is_empty(const struct pipe_inode_info *pipe) +{ + return pipe_empty(pipe->head, pipe->tail); +} + +/** + * pipe_buf_usage - Return how many pipe buffers are in use + * @pipe: the pipe + */ +static inline unsigned int pipe_buf_usage(const struct pipe_inode_info *pipe) +{ + return pipe_occupancy(pipe->head, pipe->tail); +} + +/** + * pipe_buf - Return the pipe buffer for the specified slot in the pipe ring + * @pipe: The pipe to access + * @slot: The slot of interest + */ +static inline struct pipe_buffer *pipe_buf(const struct pipe_inode_info *pipe, + unsigned int slot) +{ + return &pipe->bufs[slot & (pipe->ring_size - 1)]; +} + +/** + * pipe_head_buf - Return the pipe buffer at the head of the pipe ring + * @pipe: The pipe to access + */ +static inline struct pipe_buffer *pipe_head_buf(const struct pipe_inode_info *pipe) +{ + return pipe_buf(pipe, pipe->head); +} + +/** + * pipe_buf_get - get a reference to a pipe_buffer + * @pipe: the pipe that the buffer belongs to + * @buf: the buffer to get a reference to + * + * Return: %true if the reference was successfully obtained. + */ +static inline __must_check bool pipe_buf_get(struct pipe_inode_info *pipe, + struct pipe_buffer *buf) +{ + return buf->ops->get(pipe, buf); +} + +/** + * pipe_buf_release - put a reference to a pipe_buffer + * @pipe: the pipe that the buffer belongs to + * @buf: the buffer to put a reference to + */ +static inline void pipe_buf_release(struct pipe_inode_info *pipe, + struct pipe_buffer *buf) +{ + const struct pipe_buf_operations *ops = buf->ops; + + buf->ops = NULL; + ops->release(pipe, buf); +} + +/** + * pipe_buf_confirm - verify contents of the pipe buffer + * @pipe: the pipe that the buffer belongs to + * @buf: the buffer to confirm + */ +static inline int pipe_buf_confirm(struct pipe_inode_info *pipe, + struct pipe_buffer *buf) +{ + if (!buf->ops->confirm) + return 0; + return buf->ops->confirm(pipe, buf); +} + +/** + * pipe_buf_try_steal - attempt to take ownership of a pipe_buffer + * @pipe: the pipe that the buffer belongs to + * @buf: the buffer to attempt to steal + */ +static inline bool pipe_buf_try_steal(struct pipe_inode_info *pipe, + struct pipe_buffer *buf) +{ + if (!buf->ops->try_steal) + return false; + return buf->ops->try_steal(pipe, buf); +} + /* Differs from PIPE_BUF in that PIPE_SIZE is the length of the actual memory allocation, whereas PIPE_BUF makes atomicity guarantees. */ #define PIPE_SIZE PAGE_SIZE @@ -139,28 +308,32 @@ void pipe_lock(struct pipe_inode_info *); void pipe_unlock(struct pipe_inode_info *); void pipe_double_lock(struct pipe_inode_info *, struct pipe_inode_info *); -extern unsigned int pipe_max_size, pipe_min_size; -int pipe_proc_fn(struct ctl_table *, int, void __user *, size_t *, loff_t *); - - -/* Drop the inode semaphore and wait for a pipe event, atomically */ -void pipe_wait(struct pipe_inode_info *pipe); +/* Wait for a pipe to be readable/writable while dropping the pipe lock */ +void pipe_wait_readable(struct pipe_inode_info *); +void pipe_wait_writable(struct pipe_inode_info *); struct pipe_inode_info *alloc_pipe_info(void); void free_pipe_info(struct pipe_inode_info *); /* Generic pipe buffer ops functions */ -void *generic_pipe_buf_map(struct pipe_inode_info *, struct pipe_buffer *, int); -void generic_pipe_buf_unmap(struct pipe_inode_info *, struct pipe_buffer *, void *); -void generic_pipe_buf_get(struct pipe_inode_info *, struct pipe_buffer *); -int generic_pipe_buf_confirm(struct pipe_inode_info *, struct pipe_buffer *); -int generic_pipe_buf_steal(struct pipe_inode_info *, struct pipe_buffer *); +bool generic_pipe_buf_get(struct pipe_inode_info *, struct pipe_buffer *); +bool generic_pipe_buf_try_steal(struct pipe_inode_info *, struct pipe_buffer *); void generic_pipe_buf_release(struct pipe_inode_info *, struct pipe_buffer *); +extern const struct pipe_buf_operations nosteal_pipe_buf_ops; + +unsigned long account_pipe_buffers(struct user_struct *user, + unsigned long old, unsigned long new); +bool too_many_pipe_buffers_soft(unsigned long user_bufs); +bool too_many_pipe_buffers_hard(unsigned long user_bufs); +bool pipe_is_unprivileged_user(void); + /* for F_SETPIPE_SZ and F_GETPIPE_SZ */ -long pipe_fcntl(struct file *, unsigned int, unsigned long arg); -struct pipe_inode_info *get_pipe_info(struct file *file); +int pipe_resize_ring(struct pipe_inode_info *pipe, unsigned int nr_slots); +long pipe_fcntl(struct file *, unsigned int, unsigned int arg); +struct pipe_inode_info *get_pipe_info(struct file *file, bool for_splice); int create_pipe_files(struct file **, int); +unsigned int round_pipe_size(unsigned int size); #endif |