cb32189e23
out of cdregister() and daregister(), which are run from interrupt context. The sysctl code does blocking mallocs (M_WAITOK), which causes problems if malloc(9) actually needs to sleep. The eventual fix for this issue will involve moving the CAM probe process inside a kernel thread. For now, though, I have fixed the issue by moving dynamic sysctl variable creation for these two drivers to a task queue running in a kernel thread. The existing task queues (taskqueue_swi and taskqueue_swi_giant) run in software interrupt handlers, which wouldn't fix the problem at hand. So I have created a new task queue, taskqueue_thread, that runs inside a kernel thread. (It also runs outside of Giant -- clients must explicitly acquire and release Giant in their taskqueue functions.) scsi_cd.c: Remove sysctl variable creation code from cdregister(), and move it to a new function, cdsysctlinit(). Queue cdsysctlinit() to the taskqueue_thread taskqueue once we have fully registered the cd(4) driver instance. scsi_da.c: Remove sysctl variable creation code from daregister(), and move it to move it to a new function, dasysctlinit(). Queue dasysctlinit() to the taskqueue_thread taskqueue once we have fully registered the da(4) instance. taskqueue.h: Declare the new taskqueue_thread taskqueue, update some comments. subr_taskqueue.c: Create the new kernel thread taskqueue. This taskqueue runs outside of Giant, so any functions queued to it would need to explicitly acquire/release Giant if they need it. cd.4: Update the cd(4) man page to talk about the minimum command size sysctl/loader tunable. Also note that the changer variables are available as loader tunables as well. da.4: Update the da(4) man page to cover the retry_count, default_timeout and minimum_cmd_size sysctl variables/loader tunables. Remove references to /dev/r???, they aren't used any longer. cd.9: Update the cd(9) man page to describe the CD_Q_10_BYTE_ONLY quirk. taskqueue.9: Update the taskqueue(9) man page to describe the new thread task queue, and the taskqueue_swi_giant queue. MFC after: 3 days
124 lines
4.0 KiB
C
124 lines
4.0 KiB
C
/*-
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* Copyright (c) 2000 Doug Rabson
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#ifndef _SYS_TASKQUEUE_H_
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#define _SYS_TASKQUEUE_H_
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#ifndef _KERNEL
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#error "no user-servicable parts inside"
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#endif
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#include <sys/queue.h>
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struct taskqueue;
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/*
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* Each task includes a function which is called from
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* taskqueue_run(). The first argument is taken from the 'ta_context'
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* field of struct task and the second argument is a count of how many
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* times the task was enqueued before the call to taskqueue_run().
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*/
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typedef void task_fn_t(void *context, int pending);
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/*
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* A notification callback function which is called from
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* taskqueue_enqueue(). The context argument is given in the call to
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* taskqueue_create(). This function would normally be used to allow the
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* queue to arrange to run itself later (e.g., by scheduling a software
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* interrupt or waking a kernel thread).
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*/
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typedef void (*taskqueue_enqueue_fn)(void *context);
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struct task {
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STAILQ_ENTRY(task) ta_link; /* link for queue */
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int ta_pending; /* count times queued */
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int ta_priority; /* priority of task in queue */
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task_fn_t *ta_func; /* task handler */
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void *ta_context; /* argument for handler */
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};
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struct taskqueue *taskqueue_create(const char *name, int mflags,
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taskqueue_enqueue_fn enqueue,
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void *context);
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int taskqueue_enqueue(struct taskqueue *queue, struct task *task);
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struct taskqueue *taskqueue_find(const char *name);
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void taskqueue_free(struct taskqueue *queue);
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void taskqueue_run(struct taskqueue *queue);
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/*
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* Initialise a task structure.
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*/
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#define TASK_INIT(task, priority, func, context) do { \
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(task)->ta_pending = 0; \
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(task)->ta_priority = (priority); \
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(task)->ta_func = (func); \
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(task)->ta_context = (context); \
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} while (0)
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/*
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* Declare a reference to a taskqueue.
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*/
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#define TASKQUEUE_DECLARE(name) \
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extern struct taskqueue *taskqueue_##name
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/*
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* Define and initialise a taskqueue.
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*/
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#define TASKQUEUE_DEFINE(name, enqueue, context, init) \
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\
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struct taskqueue *taskqueue_##name; \
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\
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static void \
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taskqueue_define_##name(void *arg) \
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{ \
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taskqueue_##name = \
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taskqueue_create(#name, M_NOWAIT, (enqueue), (context)); \
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init; \
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} \
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\
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SYSINIT(taskqueue_##name, SI_SUB_CONFIGURE, SI_ORDER_SECOND, \
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taskqueue_define_##name, NULL) \
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\
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struct __hack
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/*
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* These queues are serviced by software interrupt handlers. To enqueue
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* a task, call taskqueue_enqueue(taskqueue_swi, &task) or
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* taskqueue_enqueue(taskqueue_swi_giant, &task).
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*/
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TASKQUEUE_DECLARE(swi_giant);
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TASKQUEUE_DECLARE(swi);
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/*
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* This queue is serviced by a kernel thread. To enqueue a task, call
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* taskqueue_enqueue(taskqueue_thread, &task).
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*/
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TASKQUEUE_DECLARE(thread);
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#endif /* !_SYS_TASKQUEUE_H_ */
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