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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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207 lines
5.3 KiB
C
207 lines
5.3 KiB
C
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/* -*- linux-c -*- --------------------------------------------------------- *
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*
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* linux/fs/autofs/waitq.c
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*
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* Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
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*
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* This file is part of the Linux kernel and is made available under
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* the terms of the GNU General Public License, version 2, or at your
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* option, any later version, incorporated herein by reference.
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*
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* ------------------------------------------------------------------------- */
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#include <linux/slab.h>
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#include <linux/time.h>
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#include <linux/signal.h>
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#include <linux/file.h>
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#include "autofs_i.h"
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/* We make this a static variable rather than a part of the superblock; it
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is better if we don't reassign numbers easily even across filesystems */
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static autofs_wqt_t autofs_next_wait_queue = 1;
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/* These are the signals we allow interrupting a pending mount */
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#define SHUTDOWN_SIGS (sigmask(SIGKILL) | sigmask(SIGINT) | sigmask(SIGQUIT))
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void autofs_catatonic_mode(struct autofs_sb_info *sbi)
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{
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struct autofs_wait_queue *wq, *nwq;
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DPRINTK(("autofs: entering catatonic mode\n"));
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sbi->catatonic = 1;
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wq = sbi->queues;
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sbi->queues = NULL; /* Erase all wait queues */
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while ( wq ) {
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nwq = wq->next;
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wq->status = -ENOENT; /* Magic is gone - report failure */
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kfree(wq->name);
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wq->name = NULL;
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wake_up(&wq->queue);
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wq = nwq;
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}
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fput(sbi->pipe); /* Close the pipe */
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autofs_hash_dputall(&sbi->dirhash); /* Remove all dentry pointers */
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}
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static int autofs_write(struct file *file, const void *addr, int bytes)
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{
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unsigned long sigpipe, flags;
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mm_segment_t fs;
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const char *data = (const char *)addr;
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ssize_t wr = 0;
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/** WARNING: this is not safe for writing more than PIPE_BUF bytes! **/
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sigpipe = sigismember(¤t->pending.signal, SIGPIPE);
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/* Save pointer to user space and point back to kernel space */
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fs = get_fs();
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set_fs(KERNEL_DS);
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while (bytes &&
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(wr = file->f_op->write(file,data,bytes,&file->f_pos)) > 0) {
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data += wr;
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bytes -= wr;
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}
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set_fs(fs);
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/* Keep the currently executing process from receiving a
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SIGPIPE unless it was already supposed to get one */
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if (wr == -EPIPE && !sigpipe) {
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spin_lock_irqsave(¤t->sighand->siglock, flags);
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sigdelset(¤t->pending.signal, SIGPIPE);
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recalc_sigpending();
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spin_unlock_irqrestore(¤t->sighand->siglock, flags);
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}
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return (bytes > 0);
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}
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static void autofs_notify_daemon(struct autofs_sb_info *sbi, struct autofs_wait_queue *wq)
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{
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struct autofs_packet_missing pkt;
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DPRINTK(("autofs_wait: wait id = 0x%08lx, name = ", wq->wait_queue_token));
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autofs_say(wq->name,wq->len);
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memset(&pkt,0,sizeof pkt); /* For security reasons */
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pkt.hdr.proto_version = AUTOFS_PROTO_VERSION;
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pkt.hdr.type = autofs_ptype_missing;
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pkt.wait_queue_token = wq->wait_queue_token;
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pkt.len = wq->len;
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memcpy(pkt.name, wq->name, pkt.len);
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pkt.name[pkt.len] = '\0';
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if ( autofs_write(sbi->pipe,&pkt,sizeof(struct autofs_packet_missing)) )
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autofs_catatonic_mode(sbi);
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}
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int autofs_wait(struct autofs_sb_info *sbi, struct qstr *name)
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{
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struct autofs_wait_queue *wq;
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int status;
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/* In catatonic mode, we don't wait for nobody */
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if ( sbi->catatonic )
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return -ENOENT;
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/* We shouldn't be able to get here, but just in case */
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if ( name->len > NAME_MAX )
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return -ENOENT;
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for ( wq = sbi->queues ; wq ; wq = wq->next ) {
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if ( wq->hash == name->hash &&
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wq->len == name->len &&
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wq->name && !memcmp(wq->name,name->name,name->len) )
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break;
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}
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if ( !wq ) {
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/* Create a new wait queue */
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wq = kmalloc(sizeof(struct autofs_wait_queue),GFP_KERNEL);
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if ( !wq )
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return -ENOMEM;
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wq->name = kmalloc(name->len,GFP_KERNEL);
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if ( !wq->name ) {
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kfree(wq);
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return -ENOMEM;
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}
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wq->wait_queue_token = autofs_next_wait_queue++;
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init_waitqueue_head(&wq->queue);
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wq->hash = name->hash;
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wq->len = name->len;
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wq->status = -EINTR; /* Status return if interrupted */
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memcpy(wq->name, name->name, name->len);
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wq->next = sbi->queues;
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sbi->queues = wq;
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/* autofs_notify_daemon() may block */
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wq->wait_ctr = 2;
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autofs_notify_daemon(sbi,wq);
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} else
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wq->wait_ctr++;
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/* wq->name is NULL if and only if the lock is already released */
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if ( sbi->catatonic ) {
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/* We might have slept, so check again for catatonic mode */
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wq->status = -ENOENT;
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if ( wq->name ) {
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kfree(wq->name);
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wq->name = NULL;
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}
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}
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if ( wq->name ) {
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/* Block all but "shutdown" signals while waiting */
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sigset_t sigmask;
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siginitsetinv(&sigmask, SHUTDOWN_SIGS);
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sigprocmask(SIG_BLOCK, &sigmask, &sigmask);
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interruptible_sleep_on(&wq->queue);
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sigprocmask(SIG_SETMASK, &sigmask, NULL);
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} else {
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DPRINTK(("autofs_wait: skipped sleeping\n"));
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}
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status = wq->status;
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if ( ! --wq->wait_ctr ) /* Are we the last process to need status? */
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kfree(wq);
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return status;
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}
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int autofs_wait_release(struct autofs_sb_info *sbi, autofs_wqt_t wait_queue_token, int status)
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{
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struct autofs_wait_queue *wq, **wql;
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for ( wql = &sbi->queues ; (wq = *wql) != 0 ; wql = &wq->next ) {
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if ( wq->wait_queue_token == wait_queue_token )
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break;
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}
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if ( !wq )
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return -EINVAL;
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*wql = wq->next; /* Unlink from chain */
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kfree(wq->name);
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wq->name = NULL; /* Do not wait on this queue */
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wq->status = status;
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if ( ! --wq->wait_ctr ) /* Is anyone still waiting for this guy? */
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kfree(wq);
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else
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wake_up(&wq->queue);
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return 0;
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}
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