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[/] [or1k/] [tags/] [LINUX_2_4_26_OR32/] [linux/] [linux-2.4/] [fs/] [fifo.c] - Blame information for rev 1765

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Line No. Rev Author Line
1 1275 phoenix 
/*
2 
 *  linux/fs/fifo.c
3 
 *
4 
 *  written by Paul H. Hargrove
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 *
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 *  Fixes:
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 *      10-06-1999, AV: fixed OOM handling in fifo_open(), moved
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 *                      initialization there, switched to external
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 *                      allocation of pipe_inode_info.
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 */
11 
 
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/smp_lock.h>
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static void wait_for_partner(struct inode* inode, unsigned int* cnt)
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{
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        int cur = *cnt;
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        while(cur == *cnt) {
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                pipe_wait(inode);
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                if(signal_pending(current))
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                        break;
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        }
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}
25 
 
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static void wake_up_partner(struct inode* inode)
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{
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        wake_up_interruptible(PIPE_WAIT(*inode));
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}
30 
 
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static int fifo_open(struct inode *inode, struct file *filp)
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{
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        int ret;
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        ret = -ERESTARTSYS;
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        lock_kernel();
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        if (down_interruptible(PIPE_SEM(*inode)))
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                goto err_nolock_nocleanup;
39 
 
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        if (!inode->i_pipe) {
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                ret = -ENOMEM;
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                if(!pipe_new(inode))
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                        goto err_nocleanup;
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        }
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        filp->f_version = 0;
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        switch (filp->f_mode) {
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        case 1:
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        /*
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         *  O_RDONLY
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         *  POSIX.1 says that O_NONBLOCK means return with the FIFO
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         *  opened, even when there is no process writing the FIFO.
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         */
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                filp->f_op = &read_fifo_fops;
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                PIPE_RCOUNTER(*inode)++;
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                if (PIPE_READERS(*inode)++ == 0)
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                        wake_up_partner(inode);
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                if (!PIPE_WRITERS(*inode)) {
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                        if ((filp->f_flags & O_NONBLOCK)) {
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                                /* suppress POLLHUP until we have
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                                 * seen a writer */
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                                filp->f_version = PIPE_WCOUNTER(*inode);
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                        } else
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                        {
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                                wait_for_partner(inode, &PIPE_WCOUNTER(*inode));
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                                if(signal_pending(current))
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                                        goto err_rd;
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                        }
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                }
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                break;
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        case 2:
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        /*
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         *  O_WRONLY
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         *  POSIX.1 says that O_NONBLOCK means return -1 with
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         *  errno=ENXIO when there is no process reading the FIFO.
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         */
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                ret = -ENXIO;
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                if ((filp->f_flags & O_NONBLOCK) && !PIPE_READERS(*inode))
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                        goto err;
82 
 
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                filp->f_op = &write_fifo_fops;
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                PIPE_WCOUNTER(*inode)++;
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                if (!PIPE_WRITERS(*inode)++)
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                        wake_up_partner(inode);
87 
 
88 
                if (!PIPE_READERS(*inode)) {
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                        wait_for_partner(inode, &PIPE_RCOUNTER(*inode));
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                        if (signal_pending(current))
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                                goto err_wr;
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                }
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                break;
94 
 
95 
        case 3:
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        /*
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         *  O_RDWR
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         *  POSIX.1 leaves this case "undefined" when O_NONBLOCK is set.
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         *  This implementation will NEVER block on a O_RDWR open, since
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         *  the process can at least talk to itself.
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         */
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                filp->f_op = &rdwr_fifo_fops;
103 
 
104 
                PIPE_READERS(*inode)++;
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                PIPE_WRITERS(*inode)++;
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                PIPE_RCOUNTER(*inode)++;
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                PIPE_WCOUNTER(*inode)++;
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                if (PIPE_READERS(*inode) == 1 || PIPE_WRITERS(*inode) == 1)
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                        wake_up_partner(inode);
110 
                break;
111 
 
112 
        default:
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                ret = -EINVAL;
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                goto err;
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        }
116 
 
117 
        /* Ok! */
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        up(PIPE_SEM(*inode));
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        unlock_kernel();
120 
        return 0;
121 
 
122 
err_rd:
123 
        if (!--PIPE_READERS(*inode))
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                wake_up_interruptible(PIPE_WAIT(*inode));
125 
        ret = -ERESTARTSYS;
126 
        goto err;
127 
 
128 
err_wr:
129 
        if (!--PIPE_WRITERS(*inode))
130 
                wake_up_interruptible(PIPE_WAIT(*inode));
131 
        ret = -ERESTARTSYS;
132 
        goto err;
133 
 
134 
err:
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);
139 
                kfree(info);
140 
        }
141 
 
142 
err_nocleanup:
143 
        up(PIPE_SEM(*inode));
144 
 
145 
err_nolock_nocleanup:
146 
        unlock_kernel();
147 
        return ret;
148 
}
149 
 
150 
/*
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...
154 
 */
155 
struct file_operations def_fifo_fops = {
156 
        open:           fifo_open,      /* will set read or write pipe_fops */
157 
};

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