4b6f5d20b0
This is a conversion to make the various file_operations structs in fs/ const. Basically a regexp job, with a few manual fixups The goal is both to increase correctness (harder to accidentally write to shared datastructures) and reducing the false sharing of cachelines with things that get dirty in .data (while .rodata is nicely read only and thus cache clean) Signed-off-by: Arjan van de Ven <arjan@infradead.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
150 lines
3.2 KiB
C
150 lines
3.2 KiB
C
/*
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* linux/fs/fifo.c
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*
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* 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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*/
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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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#include <linux/fs.h>
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#include <linux/pipe_fs_i.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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}
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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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}
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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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mutex_lock(PIPE_MUTEX(*inode));
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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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/* We can only do regular read/write on fifos */
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filp->f_mode &= (FMODE_READ | FMODE_WRITE);
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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;
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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);
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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;
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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;
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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);
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break;
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default:
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ret = -EINVAL;
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goto err;
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}
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/* Ok! */
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mutex_unlock(PIPE_MUTEX(*inode));
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return 0;
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err_rd:
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if (!--PIPE_READERS(*inode))
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wake_up_interruptible(PIPE_WAIT(*inode));
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ret = -ERESTARTSYS;
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goto err;
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err_wr:
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if (!--PIPE_WRITERS(*inode))
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wake_up_interruptible(PIPE_WAIT(*inode));
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ret = -ERESTARTSYS;
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goto err;
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err:
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if (!PIPE_READERS(*inode) && !PIPE_WRITERS(*inode))
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free_pipe_info(inode);
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err_nocleanup:
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mutex_unlock(PIPE_MUTEX(*inode));
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return ret;
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}
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/*
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* Dummy default file-operations: the only thing this does
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* is contain the open that then fills in the correct operations
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* depending on the access mode of the file...
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*/
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const struct file_operations def_fifo_fops = {
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.open = fifo_open, /* will set read or write pipe_fops */
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};
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