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6f6b5d1ec5
This patch changes percpu_ida_alloc() + callers to accept task state
bitmask for prepare_to_wait() for code like target/iscsi that needs
it for interruptible sleep, that is provided in a subsequent patch.
It now expects TASK_UNINTERRUPTIBLE when the caller is able to sleep
waiting for a new tag, or TASK_RUNNING when the caller cannot sleep,
and is forced to return a negative value when no tags are available.
v2 changes:
- Include blk-mq + tcm_fc + vhost/scsi + target/iscsi changes
- Drop signal_pending_state() call
v3 changes:
- Only call prepare_to_wait() + finish_wait() when != TASK_RUNNING
(PeterZ)
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Kent Overstreet <kmo@daterainc.com>
Cc: <stable@vger.kernel.org> #3.12+
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
83 lines
2.3 KiB
C
83 lines
2.3 KiB
C
#ifndef __PERCPU_IDA_H__
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#define __PERCPU_IDA_H__
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#include <linux/types.h>
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#include <linux/bitops.h>
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#include <linux/init.h>
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#include <linux/sched.h>
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#include <linux/spinlock_types.h>
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#include <linux/wait.h>
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#include <linux/cpumask.h>
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struct percpu_ida_cpu;
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struct percpu_ida {
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/*
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* number of tags available to be allocated, as passed to
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* percpu_ida_init()
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*/
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unsigned nr_tags;
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unsigned percpu_max_size;
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unsigned percpu_batch_size;
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struct percpu_ida_cpu __percpu *tag_cpu;
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/*
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* Bitmap of cpus that (may) have tags on their percpu freelists:
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* steal_tags() uses this to decide when to steal tags, and which cpus
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* to try stealing from.
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*
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* It's ok for a freelist to be empty when its bit is set - steal_tags()
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* will just keep looking - but the bitmap _must_ be set whenever a
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* percpu freelist does have tags.
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*/
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cpumask_t cpus_have_tags;
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struct {
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spinlock_t lock;
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/*
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* When we go to steal tags from another cpu (see steal_tags()),
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* we want to pick a cpu at random. Cycling through them every
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* time we steal is a bit easier and more or less equivalent:
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*/
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unsigned cpu_last_stolen;
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/* For sleeping on allocation failure */
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wait_queue_head_t wait;
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/*
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* Global freelist - it's a stack where nr_free points to the
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* top
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*/
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unsigned nr_free;
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unsigned *freelist;
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} ____cacheline_aligned_in_smp;
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};
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/*
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* Number of tags we move between the percpu freelist and the global freelist at
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* a time
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*/
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#define IDA_DEFAULT_PCPU_BATCH_MOVE 32U
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/* Max size of percpu freelist, */
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#define IDA_DEFAULT_PCPU_SIZE ((IDA_DEFAULT_PCPU_BATCH_MOVE * 3) / 2)
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int percpu_ida_alloc(struct percpu_ida *pool, int state);
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void percpu_ida_free(struct percpu_ida *pool, unsigned tag);
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void percpu_ida_destroy(struct percpu_ida *pool);
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int __percpu_ida_init(struct percpu_ida *pool, unsigned long nr_tags,
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unsigned long max_size, unsigned long batch_size);
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static inline int percpu_ida_init(struct percpu_ida *pool, unsigned long nr_tags)
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{
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return __percpu_ida_init(pool, nr_tags, IDA_DEFAULT_PCPU_SIZE,
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IDA_DEFAULT_PCPU_BATCH_MOVE);
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}
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typedef int (*percpu_ida_cb)(unsigned, void *);
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int percpu_ida_for_each_free(struct percpu_ida *pool, percpu_ida_cb fn,
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void *data);
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unsigned percpu_ida_free_tags(struct percpu_ida *pool, int cpu);
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#endif /* __PERCPU_IDA_H__ */
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