c383e2d6da
Low-level comedi drivers registered with the comedi core by `comedi_driver_register()` are linked together into a simple linked list headed by the `comedi_drivers` variable and chained by the `next` member of `struct comedi_driver`. A driver is removed from the list by `comedi_driver_unregister()`. The driver list is iterated through by `comedi_device_attach()` when the `COMEDI_DEVCONFIG` ioctl is used to attach a "legacy" device to a driver, and is also iterated through by `comedi_read()` in "proc.c" when reading "/proc/comedi". There is currently no protection against items being added or removed from the list while it is being iterated. Add a mutex `comedi_drivers_list_lock` to be locked while adding or removing an item on the list, or when iterating through the list. `comedi_driver_unregister()` also checks for and detaches any devices using the driver. This is currently done before unlinking the driver from the list, but it makes more sense to unlink the driver from the list first to prevent `comedi_device_attach()` attempting to use it, so move the unlinking part to the start of the function. Also, in `comedi_device_attach()` hold on to the mutex until we've finished attempting to attach the device to avoid it interfering with the detachment in `comedi_driver_unregister()`. Signed-off-by: Ian Abbott <abbotti@mev.co.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
98 lines
2.4 KiB
C
98 lines
2.4 KiB
C
/*
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module/proc.c
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/proc interface for comedi
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COMEDI - Linux Control and Measurement Device Interface
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Copyright (C) 1998 David A. Schleef <ds@schleef.org>
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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*/
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/*
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This is some serious bloatware.
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Taken from Dave A.'s PCL-711 driver, 'cuz I thought it
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was cool.
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*/
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#include "comedidev.h"
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#include "comedi_internal.h"
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#include <linux/proc_fs.h>
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#include <linux/seq_file.h>
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static int comedi_read(struct seq_file *m, void *v)
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{
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int i;
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int devices_q = 0;
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struct comedi_driver *driv;
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seq_printf(m,
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"comedi version " COMEDI_RELEASE "\n"
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"format string: %s\n",
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"\"%2d: %-20s %-20s %4d\", i, "
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"driver_name, board_name, n_subdevices");
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for (i = 0; i < COMEDI_NUM_BOARD_MINORS; i++) {
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struct comedi_device *dev = comedi_dev_from_minor(i);
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if (!dev)
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continue;
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if (dev->attached) {
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devices_q = 1;
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seq_printf(m, "%2d: %-20s %-20s %4d\n",
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i, dev->driver->driver_name,
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dev->board_name, dev->n_subdevices);
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}
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}
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if (!devices_q)
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seq_puts(m, "no devices\n");
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mutex_lock(&comedi_drivers_list_lock);
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for (driv = comedi_drivers; driv; driv = driv->next) {
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seq_printf(m, "%s:\n", driv->driver_name);
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for (i = 0; i < driv->num_names; i++)
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seq_printf(m, " %s\n",
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*(char **)((char *)driv->board_name +
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i * driv->offset));
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if (!driv->num_names)
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seq_printf(m, " %s\n", driv->driver_name);
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}
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mutex_unlock(&comedi_drivers_list_lock);
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return 0;
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}
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/*
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* seq_file wrappers for procfile show routines.
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*/
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static int comedi_proc_open(struct inode *inode, struct file *file)
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{
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return single_open(file, comedi_read, NULL);
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}
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static const struct file_operations comedi_proc_fops = {
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.open = comedi_proc_open,
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.read = seq_read,
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.llseek = seq_lseek,
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.release = single_release,
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};
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void comedi_proc_init(void)
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{
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proc_create("comedi", 0644, NULL, &comedi_proc_fops);
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}
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void comedi_proc_cleanup(void)
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{
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remove_proc_entry("comedi", NULL);
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}
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