/* -*- linux-c -*- --------------------------------------------------------- * * * linux/fs/autofs/waitq.c * *  Copyright 1997 Transmeta Corporation -- All Rights Reserved * * This file is part of the Linux kernel and is made available under * the terms of the GNU General Public License, version 2, or at your * option, any later version, incorporated herein by reference. * * ------------------------------------------------------------------------- */#include <linux/malloc.h>#include <linux/sched.h>#include <linux/signal.h>#include <linux/file.h>#include "autofs_i.h"/* We make this a static variable rather than a part of the superblock; it   is better if we don't reassign numbers easily even across filesystems */static int autofs_next_wait_queue = 1;void autofs_catatonic_mode(struct autofs_sb_info *sbi){	struct autofs_wait_queue *wq, *nwq;	DPRINTK(("autofs: entering catatonic mode\n"));	sbi->catatonic = 1;	wq = sbi->queues;	sbi->queues = NULL;	/* Erase all wait queues */	while ( wq ) {		nwq = wq->next;		wq->status = -ENOENT; /* Magic is gone - report failure */		kfree(wq->name);		wq->name = NULL;		wake_up(&wq->queue);		wq = nwq;	}	fput(sbi->pipe, sbi->pipe->f_inode);	/* Close the pipe */}static int autofs_write(struct file *file, const void *addr, int bytes){	unsigned short fs;	unsigned long old_signal;	const char *data = (const char *)addr;	int written = 0;	/** WARNING: this is not safe for writing more than PIPE_BUF bytes! **/	/* Save pointer to user space and point back to kernel space */	fs = get_fs();	set_fs(KERNEL_DS);	old_signal = current->signal;	while ( bytes && (written = file->f_op->write(file->f_inode,file,data,bytes)) > 0 ) {		data += written;		bytes -= written;	}	if ( written == -EPIPE && !(old_signal & (1 << (SIGPIPE-1))) ) {		/* Keep the currently executing process from receiving a		   SIGPIPE unless it was already supposed to get one */		current->signal &= ~(1 << (SIGPIPE-1));	}	set_fs(fs);	return (bytes > 0);}	static void autofs_notify_daemon(struct autofs_sb_info *sbi, struct autofs_wait_queue *wq){	struct autofs_packet_missing pkt;	DPRINTK(("autofs_wait: wait id = 0x%08lx, name = ", wq->wait_queue_token));	autofs_say(wq->name,wq->len);	memset(&pkt,0,sizeof pkt); /* For security reasons */	pkt.hdr.proto_version = AUTOFS_PROTO_VERSION;	pkt.hdr.type = autofs_ptype_missing;	pkt.wait_queue_token = wq->wait_queue_token;	pkt.len = wq->len;        memcpy(pkt.name, wq->name, pkt.len);	pkt.name[pkt.len] = '\0';	if ( autofs_write(sbi->pipe,&pkt,sizeof(struct autofs_packet_missing)) )		autofs_catatonic_mode(sbi);}int autofs_wait(struct autofs_sb_info *sbi, autofs_hash_t hash, const char *name, int len){	struct autofs_wait_queue *wq;	int status;	for ( wq = sbi->queues ; wq ; wq = wq->next ) {		if ( wq->hash == hash &&		     wq->len == len &&		     wq->name && !memcmp(wq->name,name,len) )			break;	}		if ( !wq ) {		/* Create a new wait queue */		wq = kmalloc(sizeof(struct autofs_wait_queue),GFP_KERNEL);		if ( !wq )			return -ENOMEM;		wq->name = kmalloc(len,GFP_KERNEL);		if ( !wq->name ) {			kfree(wq);			return -ENOMEM;		}		wq->wait_queue_token = autofs_next_wait_queue++;		init_waitqueue(&wq->queue);		wq->hash = hash;		wq->len = len;		wq->status = -EINTR; /* Status return if interrupted */		memcpy(wq->name, name, len);		wq->next = sbi->queues;		sbi->queues = wq;		/* autofs_notify_daemon() may block */		wq->wait_ctr = 2;		autofs_notify_daemon(sbi,wq);	} else		wq->wait_ctr++;	if ( wq->name ) {		/* wq->name is NULL if and only if the lock is released */		interruptible_sleep_on(&wq->queue);	} else {		DPRINTK(("autofs_wait: skipped sleeping\n"));	}	status = wq->status;	if ( ! --wq->wait_ctr )	/* Are we the last process to need status? */		kfree(wq);	return status;}int autofs_wait_release(struct autofs_sb_info *sbi, unsigned long wait_queue_token, int status){	struct autofs_wait_queue *wq, **wql;	for ( wql = &sbi->queues ; (wq = *wql) ; wql = &wq->next ) {		if ( wq->wait_queue_token == wait_queue_token )			break;	}	if ( !wq )		return -EINVAL;	*wql = wq->next;	/* Unlink from chain */	kfree(wq->name);	wq->name = NULL;	/* Do not wait on this queue */	wq->status = status;	if ( ! --wq->wait_ctr )	/* Is anyone still waiting for this guy? */		kfree(wq);	else		wake_up(&wq->queue);	return 0;}