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/* -*- linux-c -*- --------------------------------------------------------- *
*
* drivers/staging/autofs/waitq.c
*
* Copyright 1997-1998 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/slab.h>
#include <linux/time.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 autofs_wqt_t autofs_next_wait_queue = 1;
/* These are the signals we allow interrupting a pending mount */
#define SHUTDOWN_SIGS (sigmask(SIGKILL) | sigmask(SIGINT) | sigmask(SIGQUIT))
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); /* Close the pipe */
sbi->pipe = NULL;
autofs_hash_dputall(&sbi->dirhash); /* Remove all dentry pointers */
}
static int autofs_write(struct file *file, const void *addr, int bytes)
{
unsigned long sigpipe, flags;
mm_segment_t fs;
const char *data = (const char *)addr;
ssize_t wr = 0;
/** WARNING: this is not safe for writing more than PIPE_BUF bytes! **/
sigpipe = sigismember(¤t->pending.signal, SIGPIPE);
/* Save pointer to user space and point back to kernel space */
fs = get_fs();
set_fs(KERNEL_DS);
while (bytes &&
(wr = file->f_op->write(file,data,bytes,&file->f_pos)) > 0) {
data += wr;
bytes -= wr;
}
set_fs(fs);
/* Keep the currently executing process from receiving a
SIGPIPE unless it was already supposed to get one */
if (wr == -EPIPE && !sigpipe) {
spin_lock_irqsave(¤t->sighand->siglock, flags);
sigdelset(¤t->pending.signal, SIGPIPE);
recalc_sigpending();
spin_unlock_irqrestore(¤t->sighand->siglock, flags);
}
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, struct qstr *name)
{
struct autofs_wait_queue *wq;
int status;
/* In catatonic mode, we don't wait for nobody */
if ( sbi->catatonic )
return -ENOENT;
/* We shouldn't be able to get here, but just in case */
if ( name->len > NAME_MAX )
return -ENOENT;
for ( wq = sbi->queues ; wq ; wq = wq->next ) {
if ( wq->hash == name->hash &&
wq->len == name->len &&
wq->name && !memcmp(wq->name,name->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(name->len,GFP_KERNEL);
if ( !wq->name ) {
kfree(wq);
return -ENOMEM;
}
wq->wait_queue_token = autofs_next_wait_queue++;
init_waitqueue_head(&wq->queue);
wq->hash = name->hash;
wq->len = name->len;
wq->status = -EINTR; /* Status return if interrupted */
memcpy(wq->name, name->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++;
/* wq->name is NULL if and only if the lock is already released */
if ( sbi->catatonic ) {
/* We might have slept, so check again for catatonic mode */
wq->status = -ENOENT;
kfree(wq->name);
wq->name = NULL;
}
if ( wq->name ) {
/* Block all but "shutdown" signals while waiting */
sigset_t sigmask;
siginitsetinv(&sigmask, SHUTDOWN_SIGS);
sigprocmask(SIG_BLOCK, &sigmask, &sigmask);
interruptible_sleep_on(&wq->queue);
sigprocmask(SIG_SETMASK, &sigmask, NULL);
} 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, autofs_wqt_t wait_queue_token, int status)
{
struct autofs_wait_queue *wq, **wql;
for (wql = &sbi->queues; (wq = *wql) != NULL; 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;
}
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