arch/um/drivers/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
  13 struct xterm_wait {
  14         struct completion ready;
  15         int fd;
  16         int pid;
  17         int new_fd;
  18 };
  19
  20 static irqreturn_t xterm_interrupt(int irq, void *data)
  21 {
  22         struct xterm_wait *xterm = data;
  23         int fd;
  24
  25         fd = os_rcv_fd(xterm->fd, &xterm->pid);
  26         if (fd == -EAGAIN)
  27                 return IRQ_NONE;
  28
  29         xterm->new_fd = fd;
  30         complete(&xterm->ready);
  31
  32         return IRQ_HANDLED;
  33 }
  34
  35 int xterm_fd(int socket, int *pid_out)
  36 {
  37         struct xterm_wait *data;
  38         int err, ret;
  39
  40         data = kmalloc(sizeof(*data), GFP_KERNEL);
  41         if (data == NULL) {
  42                 printk(KERN_ERR "xterm_fd : failed to allocate xterm_wait\n");
  43                 return -ENOMEM;
  44         }
  45
  46         /* This is a locked semaphore... */
  47         *data = ((struct xterm_wait) { .fd              = socket,
  48                                        .pid             = -1,
  49                                        .new_fd          = -1 });
  50         init_completion(&data->ready);
  51
  52         err = um_request_irq(XTERM_IRQ, socket, IRQ_READ, xterm_interrupt,
  53                              IRQF_SHARED, "xterm", data);
  54         if (err) {
  55                 printk(KERN_ERR "xterm_fd : failed to get IRQ for xterm, "
  56                        "err = %d\n",  err);
  57                 ret = err;
  58                 goto out;
  59         }
  60
  61         /* ... so here we wait for an xterm interrupt.
  62          *
  63          * XXX Note, if the xterm doesn't work for some reason (eg. DISPLAY
  64          * isn't set) this will hang... */
  65         wait_for_completion(&data->ready);
  66
  67         um_free_irq(XTERM_IRQ, data);
  68
  69         ret = data->new_fd;
  70         *pid_out = data->pid;
  71  out:
  72         kfree(data);
  73
  74         return ret;
  75 }