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f823a36e83
the destroying cdev. Currently linux_destroy_dev() waits for the reference count on the linux cdev to drain, and each open file hold the reference. Practically it means that linux_destroy_dev() is blocked until all userspace processes that have the cdev open, exit. FreeBSD devfs does not have such problem, because device refcount only prevents freeing of the cdev memory, and separate 'active methods' counter blocks destroy_dev() until all threads leave the cdevsw methods. After that, attempts to enter cdevsw methods are refused with an error. Implement somewhat similar mechanism for LinuxKPI cdevs. Demote cdev refcount to only mean a hold on the linux cdev memory. Add sirefs count to track both number of threads inside the cdev methods, and for single-bit indicator that cdev is being destroyed. In the later case, the call is redirected to the dummy cdev. Reviewed by: markj Discussed with: hselasky Tested by: zeising MFC after: 1 week Sponsored by: Mellanox Technologies Differential revision: https://reviews.freebsd.org/D18606
153 lines
3.8 KiB
C
153 lines
3.8 KiB
C
/*-
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* Copyright (c) 2010 Isilon Systems, Inc.
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* Copyright (c) 2010 iX Systems, Inc.
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* Copyright (c) 2010 Panasas, Inc.
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* Copyright (c) 2013-2016 Mellanox Technologies, Ltd.
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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 unmodified, this list of conditions, and the following
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* 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 ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#ifndef _LINUX_CDEV_H_
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#define _LINUX_CDEV_H_
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#include <linux/kobject.h>
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#include <linux/sysfs.h>
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#include <linux/kdev_t.h>
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#include <linux/list.h>
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#include <asm/atomic-long.h>
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struct file_operations;
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struct inode;
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struct module;
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extern struct cdevsw linuxcdevsw;
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extern const struct kobj_type linux_cdev_ktype;
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extern const struct kobj_type linux_cdev_static_ktype;
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struct linux_cdev {
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struct kobject kobj;
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struct module *owner;
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struct cdev *cdev;
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dev_t dev;
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const struct file_operations *ops;
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u_int refs;
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u_int siref;
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};
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static inline void
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cdev_init(struct linux_cdev *cdev, const struct file_operations *ops)
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{
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kobject_init(&cdev->kobj, &linux_cdev_static_ktype);
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cdev->ops = ops;
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cdev->refs = 1;
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}
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static inline struct linux_cdev *
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cdev_alloc(void)
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{
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struct linux_cdev *cdev;
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cdev = kzalloc(sizeof(struct linux_cdev), M_WAITOK);
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if (cdev != NULL)
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kobject_init(&cdev->kobj, &linux_cdev_ktype);
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cdev->refs = 1;
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return (cdev);
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}
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static inline void
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cdev_put(struct linux_cdev *p)
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{
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kobject_put(&p->kobj);
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}
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static inline int
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cdev_add(struct linux_cdev *cdev, dev_t dev, unsigned count)
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{
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struct make_dev_args args;
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int error;
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if (count != 1)
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return (-EINVAL);
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cdev->dev = dev;
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/* Setup arguments for make_dev_s() */
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make_dev_args_init(&args);
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args.mda_devsw = &linuxcdevsw;
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args.mda_uid = 0;
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args.mda_gid = 0;
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args.mda_mode = 0700;
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args.mda_si_drv1 = cdev;
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error = make_dev_s(&args, &cdev->cdev, "%s",
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kobject_name(&cdev->kobj));
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if (error)
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return (-error);
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kobject_get(cdev->kobj.parent);
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return (0);
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}
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static inline int
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cdev_add_ext(struct linux_cdev *cdev, dev_t dev, uid_t uid, gid_t gid, int mode)
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{
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struct make_dev_args args;
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int error;
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cdev->dev = dev;
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/* Setup arguments for make_dev_s() */
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make_dev_args_init(&args);
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args.mda_devsw = &linuxcdevsw;
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args.mda_uid = uid;
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args.mda_gid = gid;
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args.mda_mode = mode;
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args.mda_si_drv1 = cdev;
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error = make_dev_s(&args, &cdev->cdev, "%s/%d",
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kobject_name(&cdev->kobj), MINOR(dev));
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if (error)
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return (-error);
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kobject_get(cdev->kobj.parent);
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return (0);
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}
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void linux_destroy_dev(struct linux_cdev *);
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static inline void
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cdev_del(struct linux_cdev *cdev)
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{
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linux_destroy_dev(cdev);
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kobject_put(&cdev->kobj);
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}
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struct linux_cdev *linux_find_cdev(const char *name, unsigned major, unsigned minor);
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#define cdev linux_cdev
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#endif /* _LINUX_CDEV_H_ */
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