cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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iocontext.h (4255B)

      1/* SPDX-License-Identifier: GPL-2.0 */
      2#ifndef IOCONTEXT_H
      3#define IOCONTEXT_H
      4
      5#include <linux/radix-tree.h>
      6#include <linux/rcupdate.h>
      7#include <linux/workqueue.h>
      8
      9enum {
     10	ICQ_EXITED		= 1 << 2,
     11	ICQ_DESTROYED		= 1 << 3,
     12};
     13
     14/*
     15 * An io_cq (icq) is association between an io_context (ioc) and a
     16 * request_queue (q).  This is used by elevators which need to track
     17 * information per ioc - q pair.
     18 *
     19 * Elevator can request use of icq by setting elevator_type->icq_size and
     20 * ->icq_align.  Both size and align must be larger than that of struct
     21 * io_cq and elevator can use the tail area for private information.  The
     22 * recommended way to do this is defining a struct which contains io_cq as
     23 * the first member followed by private members and using its size and
     24 * align.  For example,
     25 *
     26 *	struct snail_io_cq {
     27 *		struct io_cq	icq;
     28 *		int		poke_snail;
     29 *		int		feed_snail;
     30 *	};
     31 *
     32 *	struct elevator_type snail_elv_type {
     33 *		.ops =		{ ... },
     34 *		.icq_size =	sizeof(struct snail_io_cq),
     35 *		.icq_align =	__alignof__(struct snail_io_cq),
     36 *		...
     37 *	};
     38 *
     39 * If icq_size is set, block core will manage icq's.  All requests will
     40 * have its ->elv.icq field set before elevator_ops->elevator_set_req_fn()
     41 * is called and be holding a reference to the associated io_context.
     42 *
     43 * Whenever a new icq is created, elevator_ops->elevator_init_icq_fn() is
     44 * called and, on destruction, ->elevator_exit_icq_fn().  Both functions
     45 * are called with both the associated io_context and queue locks held.
     46 *
     47 * Elevator is allowed to lookup icq using ioc_lookup_icq() while holding
     48 * queue lock but the returned icq is valid only until the queue lock is
     49 * released.  Elevators can not and should not try to create or destroy
     50 * icq's.
     51 *
     52 * As icq's are linked from both ioc and q, the locking rules are a bit
     53 * complex.
     54 *
     55 * - ioc lock nests inside q lock.
     56 *
     57 * - ioc->icq_list and icq->ioc_node are protected by ioc lock.
     58 *   q->icq_list and icq->q_node by q lock.
     59 *
     60 * - ioc->icq_tree and ioc->icq_hint are protected by ioc lock, while icq
     61 *   itself is protected by q lock.  However, both the indexes and icq
     62 *   itself are also RCU managed and lookup can be performed holding only
     63 *   the q lock.
     64 *
     65 * - icq's are not reference counted.  They are destroyed when either the
     66 *   ioc or q goes away.  Each request with icq set holds an extra
     67 *   reference to ioc to ensure it stays until the request is completed.
     68 *
     69 * - Linking and unlinking icq's are performed while holding both ioc and q
     70 *   locks.  Due to the lock ordering, q exit is simple but ioc exit
     71 *   requires reverse-order double lock dance.
     72 */
     73struct io_cq {
     74	struct request_queue	*q;
     75	struct io_context	*ioc;
     76
     77	/*
     78	 * q_node and ioc_node link io_cq through icq_list of q and ioc
     79	 * respectively.  Both fields are unused once ioc_exit_icq() is
     80	 * called and shared with __rcu_icq_cache and __rcu_head which are
     81	 * used for RCU free of io_cq.
     82	 */
     83	union {
     84		struct list_head	q_node;
     85		struct kmem_cache	*__rcu_icq_cache;
     86	};
     87	union {
     88		struct hlist_node	ioc_node;
     89		struct rcu_head		__rcu_head;
     90	};
     91
     92	unsigned int		flags;
     93};
     94
     95/*
     96 * I/O subsystem state of the associated processes.  It is refcounted
     97 * and kmalloc'ed. These could be shared between processes.
     98 */
     99struct io_context {
    100	atomic_long_t refcount;
    101	atomic_t active_ref;
    102
    103	unsigned short ioprio;
    104
    105#ifdef CONFIG_BLK_ICQ
    106	/* all the fields below are protected by this lock */
    107	spinlock_t lock;
    108
    109	struct radix_tree_root	icq_tree;
    110	struct io_cq __rcu	*icq_hint;
    111	struct hlist_head	icq_list;
    112
    113	struct work_struct release_work;
    114#endif /* CONFIG_BLK_ICQ */
    115};
    116
    117struct task_struct;
    118#ifdef CONFIG_BLOCK
    119void put_io_context(struct io_context *ioc);
    120void exit_io_context(struct task_struct *task);
    121int __copy_io(unsigned long clone_flags, struct task_struct *tsk);
    122static inline int copy_io(unsigned long clone_flags, struct task_struct *tsk)
    123{
    124	if (!current->io_context)
    125		return 0;
    126	return __copy_io(clone_flags, tsk);
    127}
    128#else
    129struct io_context;
    130static inline void put_io_context(struct io_context *ioc) { }
    131static inline void exit_io_context(struct task_struct *task) { }
    132static inline int copy_io(unsigned long clone_flags, struct task_struct *tsk)
    133{
    134	return 0;
    135}
    136#endif /* CONFIG_BLOCK */
    137
    138#endif /* IOCONTEXT_H */