From 42ec57a8f68311bbbf4ff96a5d33c8a2e90b9d05 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 14 Dec 2011 00:33:37 +0100 Subject: [PATCH] block: misc ioc cleanups * int return from put_io_context() wasn't used by anybody. Make it return void like other put functions and docbook-fy the function comment. * Reorder dummy declarations for !CONFIG_BLOCK case a bit. * Make alloc_ioc_context() use __GFP_ZERO allocation, take init out of if block and drop 0'ing. * Docbook-fy current_io_context() comment. This patch doesn't introduce any functional change. Signed-off-by: Tejun Heo Signed-off-by: Jens Axboe --- block/blk-ioc.c | 72 +++++++++++++++++++-------------------- include/linux/iocontext.h | 12 ++----- 2 files changed, 39 insertions(+), 45 deletions(-) diff --git a/block/blk-ioc.c b/block/blk-ioc.c index 6f9bbd978653..8bebf06bac76 100644 --- a/block/blk-ioc.c +++ b/block/blk-ioc.c @@ -27,26 +27,28 @@ static void cfq_dtor(struct io_context *ioc) } } -/* - * IO Context helper functions. put_io_context() returns 1 if there are no - * more users of this io context, 0 otherwise. +/** + * put_io_context - put a reference of io_context + * @ioc: io_context to put + * + * Decrement reference count of @ioc and release it if the count reaches + * zero. */ -int put_io_context(struct io_context *ioc) +void put_io_context(struct io_context *ioc) { if (ioc == NULL) - return 1; + return; - BUG_ON(atomic_long_read(&ioc->refcount) == 0); + BUG_ON(atomic_long_read(&ioc->refcount) <= 0); - if (atomic_long_dec_and_test(&ioc->refcount)) { - rcu_read_lock(); - cfq_dtor(ioc); - rcu_read_unlock(); + if (!atomic_long_dec_and_test(&ioc->refcount)) + return; - kmem_cache_free(iocontext_cachep, ioc); - return 1; - } - return 0; + rcu_read_lock(); + cfq_dtor(ioc); + rcu_read_unlock(); + + kmem_cache_free(iocontext_cachep, ioc); } EXPORT_SYMBOL(put_io_context); @@ -84,33 +86,31 @@ struct io_context *alloc_io_context(gfp_t gfp_flags, int node) { struct io_context *ioc; - ioc = kmem_cache_alloc_node(iocontext_cachep, gfp_flags, node); - if (ioc) { - atomic_long_set(&ioc->refcount, 1); - atomic_set(&ioc->nr_tasks, 1); - spin_lock_init(&ioc->lock); - ioc->ioprio_changed = 0; - ioc->ioprio = 0; - ioc->last_waited = 0; /* doesn't matter... */ - ioc->nr_batch_requests = 0; /* because this is 0 */ - INIT_RADIX_TREE(&ioc->radix_root, GFP_ATOMIC | __GFP_HIGH); - INIT_HLIST_HEAD(&ioc->cic_list); - ioc->ioc_data = NULL; -#if defined(CONFIG_BLK_CGROUP) || defined(CONFIG_BLK_CGROUP_MODULE) - ioc->cgroup_changed = 0; -#endif - } + ioc = kmem_cache_alloc_node(iocontext_cachep, gfp_flags | __GFP_ZERO, + node); + if (unlikely(!ioc)) + return NULL; + + /* initialize */ + atomic_long_set(&ioc->refcount, 1); + atomic_set(&ioc->nr_tasks, 1); + spin_lock_init(&ioc->lock); + INIT_RADIX_TREE(&ioc->radix_root, GFP_ATOMIC | __GFP_HIGH); + INIT_HLIST_HEAD(&ioc->cic_list); return ioc; } -/* - * If the current task has no IO context then create one and initialise it. - * Otherwise, return its existing IO context. +/** + * current_io_context - get io_context of %current + * @gfp_flags: allocation flags, used if allocation is necessary + * @node: allocation node, used if allocation is necessary * - * This returned IO context doesn't have a specifically elevated refcount, - * but since the current task itself holds a reference, the context can be - * used in general code, so long as it stays within `current` context. + * Return io_context of %current. If it doesn't exist, it is created with + * @gfp_flags and @node. The returned io_context does NOT have its + * reference count incremented. Because io_context is exited only on task + * exit, %current can be sure that the returned io_context is valid and + * alive as long as it is executing. */ struct io_context *current_io_context(gfp_t gfp_flags, int node) { diff --git a/include/linux/iocontext.h b/include/linux/iocontext.h index 5037a0ad2312..8a6ecb66346f 100644 --- a/include/linux/iocontext.h +++ b/include/linux/iocontext.h @@ -76,20 +76,14 @@ static inline struct io_context *ioc_task_link(struct io_context *ioc) struct task_struct; #ifdef CONFIG_BLOCK -int put_io_context(struct io_context *ioc); +void put_io_context(struct io_context *ioc); void exit_io_context(struct task_struct *task); struct io_context *get_io_context(gfp_t gfp_flags, int node); struct io_context *alloc_io_context(gfp_t gfp_flags, int node); #else -static inline void exit_io_context(struct task_struct *task) -{ -} - struct io_context; -static inline int put_io_context(struct io_context *ioc) -{ - return 1; -} +static inline void put_io_context(struct io_context *ioc) { } +static inline void exit_io_context(struct task_struct *task) { } #endif #endif -- 2.20.1