xref: /linux/arch/um/drivers/xterm_kern.c (revision a1ff5a7d78a036d6c2178ee5acd6ba4946243800)
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 
xterm_interrupt(int irq,void * data)21 static irqreturn_t xterm_interrupt(int irq, void *data)
22 {
23 	struct xterm_wait *xterm = data;
24 	int fd = -1, n_fds = 1;
25 	ssize_t ret;
26 
27 	ret = os_rcv_fd_msg(xterm->fd, &fd, n_fds,
28 			    &xterm->pid, sizeof(xterm->pid));
29 	if (ret == -EAGAIN)
30 		return IRQ_NONE;
31 
32 	if (ret < 0)
33 		fd = ret;
34 	else if (ret != sizeof(xterm->pid))
35 		fd = -EMSGSIZE;
36 
37 	xterm->new_fd = fd;
38 	complete(&xterm->ready);
39 
40 	return IRQ_HANDLED;
41 }
42 
xterm_fd(int socket,int * pid_out)43 int xterm_fd(int socket, int *pid_out)
44 {
45 	struct xterm_wait *data;
46 	int err, ret;
47 
48 	data = kmalloc(sizeof(*data), GFP_KERNEL);
49 	if (data == NULL) {
50 		printk(KERN_ERR "xterm_fd : failed to allocate xterm_wait\n");
51 		return -ENOMEM;
52 	}
53 
54 	/* This is a locked semaphore... */
55 	*data = ((struct xterm_wait) { .fd 		= socket,
56 				       .pid 		= -1,
57 				       .new_fd	 	= -1 });
58 	init_completion(&data->ready);
59 
60 	err = um_request_irq(XTERM_IRQ, socket, IRQ_READ, xterm_interrupt,
61 			     IRQF_SHARED, "xterm", data);
62 	if (err < 0) {
63 		printk(KERN_ERR "xterm_fd : failed to get IRQ for xterm, "
64 		       "err = %d\n",  err);
65 		ret = err;
66 		goto out;
67 	}
68 
69 	/* ... so here we wait for an xterm interrupt.
70 	 *
71 	 * XXX Note, if the xterm doesn't work for some reason (eg. DISPLAY
72 	 * isn't set) this will hang... */
73 	wait_for_completion(&data->ready);
74 
75 	um_free_irq(XTERM_IRQ, data);
76 
77 	ret = data->new_fd;
78 	*pid_out = data->pid;
79  out:
80 	kfree(data);
81 
82 	return ret;
83 }
84