[PATCH] Driver Core: remove driver model detach_state
[linux-2.6/verdex.git] / fs / fifo.c
blob5455916241f04efb9d1f8fe90bab1d73bcaae0f5
1 /*
2 * linux/fs/fifo.c
4 * written by Paul H. Hargrove
6 * Fixes:
7 * 10-06-1999, AV: fixed OOM handling in fifo_open(), moved
8 * initialization there, switched to external
9 * allocation of pipe_inode_info.
12 #include <linux/mm.h>
13 #include <linux/slab.h>
14 #include <linux/smp_lock.h>
15 #include <linux/fs.h>
16 #include <linux/pipe_fs_i.h>
18 static void wait_for_partner(struct inode* inode, unsigned int* cnt)
20 int cur = *cnt;
21 while(cur == *cnt) {
22 pipe_wait(inode);
23 if(signal_pending(current))
24 break;
28 static void wake_up_partner(struct inode* inode)
30 wake_up_interruptible(PIPE_WAIT(*inode));
33 static int fifo_open(struct inode *inode, struct file *filp)
35 int ret;
37 ret = -ERESTARTSYS;
38 if (down_interruptible(PIPE_SEM(*inode)))
39 goto err_nolock_nocleanup;
41 if (!inode->i_pipe) {
42 ret = -ENOMEM;
43 if(!pipe_new(inode))
44 goto err_nocleanup;
46 filp->f_version = 0;
48 /* We can only do regular read/write on fifos */
49 filp->f_mode &= (FMODE_READ | FMODE_WRITE);
51 switch (filp->f_mode) {
52 case 1:
54 * O_RDONLY
55 * POSIX.1 says that O_NONBLOCK means return with the FIFO
56 * opened, even when there is no process writing the FIFO.
58 filp->f_op = &read_fifo_fops;
59 PIPE_RCOUNTER(*inode)++;
60 if (PIPE_READERS(*inode)++ == 0)
61 wake_up_partner(inode);
63 if (!PIPE_WRITERS(*inode)) {
64 if ((filp->f_flags & O_NONBLOCK)) {
65 /* suppress POLLHUP until we have
66 * seen a writer */
67 filp->f_version = PIPE_WCOUNTER(*inode);
68 } else
70 wait_for_partner(inode, &PIPE_WCOUNTER(*inode));
71 if(signal_pending(current))
72 goto err_rd;
75 break;
77 case 2:
79 * O_WRONLY
80 * POSIX.1 says that O_NONBLOCK means return -1 with
81 * errno=ENXIO when there is no process reading the FIFO.
83 ret = -ENXIO;
84 if ((filp->f_flags & O_NONBLOCK) && !PIPE_READERS(*inode))
85 goto err;
87 filp->f_op = &write_fifo_fops;
88 PIPE_WCOUNTER(*inode)++;
89 if (!PIPE_WRITERS(*inode)++)
90 wake_up_partner(inode);
92 if (!PIPE_READERS(*inode)) {
93 wait_for_partner(inode, &PIPE_RCOUNTER(*inode));
94 if (signal_pending(current))
95 goto err_wr;
97 break;
99 case 3:
101 * O_RDWR
102 * POSIX.1 leaves this case "undefined" when O_NONBLOCK is set.
103 * This implementation will NEVER block on a O_RDWR open, since
104 * the process can at least talk to itself.
106 filp->f_op = &rdwr_fifo_fops;
108 PIPE_READERS(*inode)++;
109 PIPE_WRITERS(*inode)++;
110 PIPE_RCOUNTER(*inode)++;
111 PIPE_WCOUNTER(*inode)++;
112 if (PIPE_READERS(*inode) == 1 || PIPE_WRITERS(*inode) == 1)
113 wake_up_partner(inode);
114 break;
116 default:
117 ret = -EINVAL;
118 goto err;
121 /* Ok! */
122 up(PIPE_SEM(*inode));
123 return 0;
125 err_rd:
126 if (!--PIPE_READERS(*inode))
127 wake_up_interruptible(PIPE_WAIT(*inode));
128 ret = -ERESTARTSYS;
129 goto err;
131 err_wr:
132 if (!--PIPE_WRITERS(*inode))
133 wake_up_interruptible(PIPE_WAIT(*inode));
134 ret = -ERESTARTSYS;
135 goto err;
137 err:
138 if (!PIPE_READERS(*inode) && !PIPE_WRITERS(*inode))
139 free_pipe_info(inode);
141 err_nocleanup:
142 up(PIPE_SEM(*inode));
144 err_nolock_nocleanup:
145 return ret;
149 * Dummy default file-operations: the only thing this does
150 * is contain the open that then fills in the correct operations
151 * depending on the access mode of the file...
153 struct file_operations def_fifo_fops = {
154 .open = fifo_open, /* will set read or write pipe_fops */