From 9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00 Mon Sep 17 00:00:00 2001 From: Yunhong Jiang Date: Tue, 4 Aug 2015 12:17:53 -0700 Subject: Add the rt linux 4.1.3-rt3 as base Import the rt linux 4.1.3-rt3 as OPNFV kvm base. It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and the base is: commit 0917f823c59692d751951bf5ea699a2d1e2f26a2 Author: Sebastian Andrzej Siewior Date: Sat Jul 25 12:13:34 2015 +0200 Prepare v4.1.3-rt3 Signed-off-by: Sebastian Andrzej Siewior We lose all the git history this way and it's not good. We should apply another opnfv project repo in future. Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423 Signed-off-by: Yunhong Jiang --- kernel/include/linux/iocontext.h | 157 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 157 insertions(+) create mode 100644 kernel/include/linux/iocontext.h (limited to 'kernel/include/linux/iocontext.h') diff --git a/kernel/include/linux/iocontext.h b/kernel/include/linux/iocontext.h new file mode 100644 index 000000000..df38db2ef --- /dev/null +++ b/kernel/include/linux/iocontext.h @@ -0,0 +1,157 @@ +#ifndef IOCONTEXT_H +#define IOCONTEXT_H + +#include +#include +#include + +enum { + ICQ_EXITED = 1 << 2, +}; + +/* + * An io_cq (icq) is association between an io_context (ioc) and a + * request_queue (q). This is used by elevators which need to track + * information per ioc - q pair. + * + * Elevator can request use of icq by setting elevator_type->icq_size and + * ->icq_align. Both size and align must be larger than that of struct + * io_cq and elevator can use the tail area for private information. The + * recommended way to do this is defining a struct which contains io_cq as + * the first member followed by private members and using its size and + * align. For example, + * + * struct snail_io_cq { + * struct io_cq icq; + * int poke_snail; + * int feed_snail; + * }; + * + * struct elevator_type snail_elv_type { + * .ops = { ... }, + * .icq_size = sizeof(struct snail_io_cq), + * .icq_align = __alignof__(struct snail_io_cq), + * ... + * }; + * + * If icq_size is set, block core will manage icq's. All requests will + * have its ->elv.icq field set before elevator_ops->elevator_set_req_fn() + * is called and be holding a reference to the associated io_context. + * + * Whenever a new icq is created, elevator_ops->elevator_init_icq_fn() is + * called and, on destruction, ->elevator_exit_icq_fn(). Both functions + * are called with both the associated io_context and queue locks held. + * + * Elevator is allowed to lookup icq using ioc_lookup_icq() while holding + * queue lock but the returned icq is valid only until the queue lock is + * released. Elevators can not and should not try to create or destroy + * icq's. + * + * As icq's are linked from both ioc and q, the locking rules are a bit + * complex. + * + * - ioc lock nests inside q lock. + * + * - ioc->icq_list and icq->ioc_node are protected by ioc lock. + * q->icq_list and icq->q_node by q lock. + * + * - ioc->icq_tree and ioc->icq_hint are protected by ioc lock, while icq + * itself is protected by q lock. However, both the indexes and icq + * itself are also RCU managed and lookup can be performed holding only + * the q lock. + * + * - icq's are not reference counted. They are destroyed when either the + * ioc or q goes away. Each request with icq set holds an extra + * reference to ioc to ensure it stays until the request is completed. + * + * - Linking and unlinking icq's are performed while holding both ioc and q + * locks. Due to the lock ordering, q exit is simple but ioc exit + * requires reverse-order double lock dance. + */ +struct io_cq { + struct request_queue *q; + struct io_context *ioc; + + /* + * q_node and ioc_node link io_cq through icq_list of q and ioc + * respectively. Both fields are unused once ioc_exit_icq() is + * called and shared with __rcu_icq_cache and __rcu_head which are + * used for RCU free of io_cq. + */ + union { + struct list_head q_node; + struct kmem_cache *__rcu_icq_cache; + }; + union { + struct hlist_node ioc_node; + struct rcu_head __rcu_head; + }; + + unsigned int flags; +}; + +/* + * I/O subsystem state of the associated processes. It is refcounted + * and kmalloc'ed. These could be shared between processes. + */ +struct io_context { + atomic_long_t refcount; + atomic_t active_ref; + atomic_t nr_tasks; + + /* all the fields below are protected by this lock */ + spinlock_t lock; + + unsigned short ioprio; + + /* + * For request batching + */ + int nr_batch_requests; /* Number of requests left in the batch */ + unsigned long last_waited; /* Time last woken after wait for request */ + + struct radix_tree_root icq_tree; + struct io_cq __rcu *icq_hint; + struct hlist_head icq_list; + + struct work_struct release_work; +}; + +/** + * get_io_context_active - get active reference on ioc + * @ioc: ioc of interest + * + * Only iocs with active reference can issue new IOs. This function + * acquires an active reference on @ioc. The caller must already have an + * active reference on @ioc. + */ +static inline void get_io_context_active(struct io_context *ioc) +{ + WARN_ON_ONCE(atomic_long_read(&ioc->refcount) <= 0); + WARN_ON_ONCE(atomic_read(&ioc->active_ref) <= 0); + atomic_long_inc(&ioc->refcount); + atomic_inc(&ioc->active_ref); +} + +static inline void ioc_task_link(struct io_context *ioc) +{ + get_io_context_active(ioc); + + WARN_ON_ONCE(atomic_read(&ioc->nr_tasks) <= 0); + atomic_inc(&ioc->nr_tasks); +} + +struct task_struct; +#ifdef CONFIG_BLOCK +void put_io_context(struct io_context *ioc); +void put_io_context_active(struct io_context *ioc); +void exit_io_context(struct task_struct *task); +struct io_context *get_task_io_context(struct task_struct *task, + gfp_t gfp_flags, int node); +#else +struct io_context; +static inline void put_io_context(struct io_context *ioc) { } +static inline void exit_io_context(struct task_struct *task) { } +#endif + +#endif -- cgit 1.2.3-korg