mirror_zfs/include/sys/taskq.h
Brian Behlendorf 7257ec4185 Fix taskq_wait() not waiting bug
I'm very surprised this has not surfaced until now.  But the taskq_wait()
implementation work only wait successfully the first time it was called.
Subsequent usage of taskq_wait() on the taskq would not wait.

The issue was caused by tq->tq_lowest_id being set to MAX_INT after the
first wait completed.  This caused subsequent waits which check that the
waiting id is less than the lowest taskq id to always succeed.  The fix
is to ensure that tq->tq_lowest_id is never set larger than tq->tq_next.id.

Additional fixes which were added to this patch include:
1) Fix a race by placing the taskq_wait_check() in the tq->tq_lock spinlock.
2) taskq_wait() should wait for the largest outstanding id.
3) Multiple spelling corrections.
4) Added taskq wait regression test to validate correct behavior.
2009-03-15 15:13:49 -07:00

109 lines
4.1 KiB
C

/*
* This file is part of the SPL: Solaris Porting Layer.
*
* Copyright (c) 2008 Lawrence Livermore National Security, LLC.
* Produced at Lawrence Livermore National Laboratory
* Written by:
* Brian Behlendorf <behlendorf1@llnl.gov>,
* Herb Wartens <wartens2@llnl.gov>,
* Jim Garlick <garlick@llnl.gov>
* UCRL-CODE-235197
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#ifndef _SPL_TASKQ_H
#define _SPL_TASKQ_H
#ifdef __cplusplus
extern "C" {
#endif
#include <linux/module.h>
#include <linux/gfp.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/kthread.h>
#include <sys/types.h>
#include <sys/thread.h>
#define TASKQ_NAMELEN 31
#define TASKQ_PREPOPULATE 0x00000001
#define TASKQ_CPR_SAFE 0x00000002
#define TASKQ_DYNAMIC 0x00000004
typedef unsigned long taskqid_t;
typedef void (task_func_t)(void *);
/*
* Flags for taskq_dispatch. TQ_SLEEP/TQ_NOSLEEP should be same as
* KM_SLEEP/KM_NOSLEEP. TQ_NOQUEUE/TQ_NOALLOC are set particularly
* large so as not to conflict with already used GFP_* defines.
*/
#define TQ_SLEEP KM_SLEEP
#define TQ_NOSLEEP KM_NOSLEEP
#define TQ_NOQUEUE 0x01000000
#define TQ_NOALLOC 0x02000000
#define TQ_NEW 0x04000000
#define TQ_ACTIVE 0x80000000
typedef struct taskq {
spinlock_t tq_lock; /* protects taskq_t */
unsigned long tq_lock_flags; /* interrupt state */
struct task_struct **tq_threads; /* thread pointers */
const char *tq_name; /* taskq name */
int tq_nactive; /* # of active threads */
int tq_nthreads; /* # of total threads */
int tq_pri; /* priority */
int tq_minalloc; /* min task_t pool size */
int tq_maxalloc; /* max task_t pool size */
int tq_nalloc; /* cur task_t pool size */
uint_t tq_flags; /* flags */
taskqid_t tq_next_id; /* next pend/work id */
taskqid_t tq_lowest_id; /* lowest pend/work id */
struct list_head tq_free_list; /* free task_t's */
struct list_head tq_work_list; /* work task_t's */
struct list_head tq_pend_list; /* pending task_t's */
wait_queue_head_t tq_work_waitq; /* new work waitq */
wait_queue_head_t tq_wait_waitq; /* wait waitq */
} taskq_t;
/* Global system-wide dynamic task queue available for all consumers */
extern taskq_t *system_taskq;
extern taskqid_t __taskq_dispatch(taskq_t *, task_func_t, void *, uint_t);
extern taskq_t *__taskq_create(const char *, int, pri_t, int, int, uint_t);
extern void __taskq_destroy(taskq_t *);
extern void __taskq_wait_id(taskq_t *, taskqid_t);
extern void __taskq_wait(taskq_t *);
extern int __taskq_member(taskq_t *, void *);
int spl_taskq_init(void);
void spl_taskq_fini(void);
#define taskq_member(tq, t) __taskq_member(tq, t)
#define taskq_wait_id(tq, id) __taskq_wait_id(tq, id)
#define taskq_wait(tq) __taskq_wait(tq)
#define taskq_dispatch(tq, f, p, fl) __taskq_dispatch(tq, f, p, fl)
#define taskq_create(n, th, p, mi, ma, fl) __taskq_create(n, th, p, mi, ma, fl)
#define taskq_destroy(tq) __taskq_destroy(tq)
#ifdef __cplusplus
}
#endif
#endif /* _SPL_TASKQ_H */