xterm_kern.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
   4  */
   5
   6 #include <linux/slab.h>
   7 #include <linux/completion.h>
   8 #include <linux/irqreturn.h>
   9 #include <asm/irq.h>
  10 #include <irq_kern.h>
  11 #include <os.h>
  12 #include "xterm.h"
  13
  14 struct xterm_wait {
  15         struct completion ready;
  16         int fd;
  17         int pid;
  18         int new_fd;
  19 };
  20
  21 static irqreturn_t xterm_interrupt(int irq, void *data)
  22 {
  23         struct xterm_wait *xterm = data;
  24         int fd;
  25
  26         fd = os_rcv_fd(xterm->fd, &xterm->pid);
  27         if (fd == -EAGAIN)
  28                 return IRQ_NONE;
  29
  30         xterm->new_fd = fd;
  31         complete(&xterm->ready);
  32
  33         return IRQ_HANDLED;
  34 }
  35
  36 int xterm_fd(int socket, int *pid_out)
  37 {
  38         struct xterm_wait *data;
  39         int err, ret;
  40
  41         data = kmalloc(sizeof(*data), GFP_KERNEL);
  42         if (data == NULL) {
  43                 printk(KERN_ERR "xterm_fd : failed to allocate xterm_wait\n");
  44                 return -ENOMEM;
  45         }
  46
  47         /* This is a locked semaphore... */
  48         *data = ((struct xterm_wait) { .fd              = socket,
  49                                        .pid             = -1,
  50                                        .new_fd          = -1 });
  51         init_completion(&data->ready);
  52
  53         err = um_request_irq(XTERM_IRQ, socket, IRQ_READ, xterm_interrupt,
  54                              IRQF_SHARED, "xterm", data);
  55         if (err < 0) {
  56                 printk(KERN_ERR "xterm_fd : failed to get IRQ for xterm, "
  57                        "err = %d\n",  err);
  58                 ret = err;
  59                 goto out;
  60         }
  61
  62         /* ... so here we wait for an xterm interrupt.
  63          *
  64          * XXX Note, if the xterm doesn't work for some reason (eg. DISPLAY
  65          * isn't set) this will hang... */
  66         wait_for_completion(&data->ready);
  67
  68         um_free_irq(XTERM_IRQ, data);
  69
  70         ret = data->new_fd;
  71         *pid_out = data->pid;
  72  out:
  73         kfree(data);
  74
  75         return ret;
  76 }