4 * written by Paul H. Hargrove
7 * 10-06-1999, AV: fixed OOM handling in fifo_open(), moved
8 * initialization there, switched to external
9 * allocation of pipe_inode_info.
13 #include <linux/slab.h>
14 #include <linux/smp_lock.h>
16 static void wait_for_partner(struct inode* inode, unsigned int* cnt)
21 if(signal_pending(current))
26 static void wake_up_partner(struct inode* inode)
28 wake_up_interruptible(PIPE_WAIT(*inode));
31 static int fifo_open(struct inode *inode, struct file *filp)
37 if (down_interruptible(PIPE_SEM(*inode)))
38 goto err_nolock_nocleanup;
47 switch (filp->f_mode) {
51 * POSIX.1 says that O_NONBLOCK means return with the FIFO
52 * opened, even when there is no process writing the FIFO.
54 filp->f_op = &read_fifo_fops;
55 PIPE_RCOUNTER(*inode)++;
56 if (PIPE_READERS(*inode)++ == 0)
57 wake_up_partner(inode);
59 if (!PIPE_WRITERS(*inode)) {
60 if ((filp->f_flags & O_NONBLOCK)) {
61 /* suppress POLLHUP until we have
63 filp->f_version = PIPE_WCOUNTER(*inode);
66 wait_for_partner(inode, &PIPE_WCOUNTER(*inode));
67 if(signal_pending(current))
76 * POSIX.1 says that O_NONBLOCK means return -1 with
77 * errno=ENXIO when there is no process reading the FIFO.
80 if ((filp->f_flags & O_NONBLOCK) && !PIPE_READERS(*inode))
83 filp->f_op = &write_fifo_fops;
84 PIPE_WCOUNTER(*inode)++;
85 if (!PIPE_WRITERS(*inode)++)
86 wake_up_partner(inode);
88 if (!PIPE_READERS(*inode)) {
89 wait_for_partner(inode, &PIPE_RCOUNTER(*inode));
90 if (signal_pending(current))
98 * POSIX.1 leaves this case "undefined" when O_NONBLOCK is set.
99 * This implementation will NEVER block on a O_RDWR open, since
100 * the process can at least talk to itself.
102 filp->f_op = &rdwr_fifo_fops;
104 PIPE_READERS(*inode)++;
105 PIPE_WRITERS(*inode)++;
106 PIPE_RCOUNTER(*inode)++;
107 PIPE_WCOUNTER(*inode)++;
108 if (PIPE_READERS(*inode) == 1 || PIPE_WRITERS(*inode) == 1)
109 wake_up_partner(inode);
118 up(PIPE_SEM(*inode));
123 if (!--PIPE_READERS(*inode))
124 wake_up_interruptible(PIPE_WAIT(*inode));
129 if (!--PIPE_WRITERS(*inode))
130 wake_up_interruptible(PIPE_WAIT(*inode));
135 if (!PIPE_READERS(*inode) && !PIPE_WRITERS(*inode)) {
136 struct pipe_inode_info *info = inode->i_pipe;
137 inode->i_pipe = NULL;
138 free_page((unsigned long)info->base);
143 up(PIPE_SEM(*inode));
145 err_nolock_nocleanup:
151 * Dummy default file-operations: the only thing this does
152 * is contain the open that then fills in the correct operations
153 * depending on the access mode of the file...
155 struct file_operations def_fifo_fops = {
156 open: fifo_open, /* will set read or write pipe_fops */