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c30c9b1518
w1_control_thread was removed which would wake up every second and process newly registered family codes and complete some final cleanup for a removed master. Those routines were moved to the threads that were previously requesting those operations. A new function w1_reconnect_slaves takes care of reconnecting existing slave devices when a new family code is registered or removed. The removal case was missing and would cause a deadlock waiting for the family code reference count to decrease, which will now happen. A problem with registering a family code was fixed. A slave device would be unattached if it wasn't yet claimed, then attached at the end of the list, two unclaimed slaves would cause an infinite loop. The struct w1_bus_master.search now takes a pointer to the struct w1_master device to avoid searching for it, which would have caused a lock ordering deadlock with the removal of w1_control_thread. Signed-off-by: David Fries <david@fries.net> Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
145 lines
3.1 KiB
C
145 lines
3.1 KiB
C
/*
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* w1_family.c
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*
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* Copyright (c) 2004 Evgeniy Polyakov <johnpol@2ka.mipt.ru>
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*
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*
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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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*
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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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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include <linux/spinlock.h>
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#include <linux/list.h>
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#include <linux/sched.h> /* schedule_timeout() */
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#include <linux/delay.h>
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#include "w1_family.h"
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#include "w1.h"
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DEFINE_SPINLOCK(w1_flock);
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static LIST_HEAD(w1_families);
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int w1_register_family(struct w1_family *newf)
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{
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struct list_head *ent, *n;
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struct w1_family *f;
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int ret = 0;
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spin_lock(&w1_flock);
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list_for_each_safe(ent, n, &w1_families) {
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f = list_entry(ent, struct w1_family, family_entry);
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if (f->fid == newf->fid) {
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ret = -EEXIST;
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break;
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}
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}
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if (!ret) {
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atomic_set(&newf->refcnt, 0);
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newf->need_exit = 0;
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list_add_tail(&newf->family_entry, &w1_families);
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}
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spin_unlock(&w1_flock);
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/* check default devices against the new set of drivers */
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w1_reconnect_slaves(newf, 1);
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return ret;
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}
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void w1_unregister_family(struct w1_family *fent)
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{
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struct list_head *ent, *n;
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struct w1_family *f;
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spin_lock(&w1_flock);
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list_for_each_safe(ent, n, &w1_families) {
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f = list_entry(ent, struct w1_family, family_entry);
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if (f->fid == fent->fid) {
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list_del(&fent->family_entry);
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break;
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}
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}
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fent->need_exit = 1;
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spin_unlock(&w1_flock);
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/* deatch devices using this family code */
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w1_reconnect_slaves(fent, 0);
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while (atomic_read(&fent->refcnt)) {
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printk(KERN_INFO "Waiting for family %u to become free: refcnt=%d.\n",
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fent->fid, atomic_read(&fent->refcnt));
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if (msleep_interruptible(1000))
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flush_signals(current);
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}
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}
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/*
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* Should be called under w1_flock held.
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*/
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struct w1_family * w1_family_registered(u8 fid)
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{
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struct list_head *ent, *n;
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struct w1_family *f = NULL;
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int ret = 0;
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list_for_each_safe(ent, n, &w1_families) {
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f = list_entry(ent, struct w1_family, family_entry);
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if (f->fid == fid) {
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ret = 1;
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break;
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}
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}
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return (ret) ? f : NULL;
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}
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static void __w1_family_put(struct w1_family *f)
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{
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if (atomic_dec_and_test(&f->refcnt))
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f->need_exit = 1;
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}
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void w1_family_put(struct w1_family *f)
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{
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spin_lock(&w1_flock);
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__w1_family_put(f);
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spin_unlock(&w1_flock);
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}
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#if 0
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void w1_family_get(struct w1_family *f)
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{
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spin_lock(&w1_flock);
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__w1_family_get(f);
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spin_unlock(&w1_flock);
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}
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#endif /* 0 */
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void __w1_family_get(struct w1_family *f)
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{
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smp_mb__before_atomic_inc();
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atomic_inc(&f->refcnt);
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smp_mb__after_atomic_inc();
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}
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EXPORT_SYMBOL(w1_unregister_family);
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EXPORT_SYMBOL(w1_register_family);
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