On Tue, 1 Jul 2008 11:03:02 +0200 Denys Vlasenko <vda.linux@xxxxxxxxxxxxxx> wrote:
> Hi Andrew, Al,
>
> I posted this patch a few months ago, but it apparently
> fell thru cracks. Here we go again.
>
> I noticed that read/write/rdwr_pipe_fops are (1) const and
> (2) exactly identical to xxx_fifo_fops, which are also const.
>
> Attached patch #defines xxx_pipe_fops as aliases to xxx_fifo_fops.
> Size difference:
>
> # size linux-2.6.25-rc6*/*/pipe.o
> text data bss dec hex filename
> 6534 144 0 6678 1a16 linux-2.6.25-rc6/fs/pipe.o
> 5862 144 0 6006 1776 linux-2.6.25-rc6-pt/fs/pipe.o
>
> Run-tested on 2.6.26-rc8. Please apply.
>
> Signed-off-by: Denys Vlasenko <vda.linux@xxxxxxxxxxxxxx>
<argh, an attachment. save-as, read, edit..>
--- linux-2.6.25-rc6.src/fs/pipe.c Sat Mar 22 23:00:34 2008
> +++ linux-2.6.25-rc6.pipe/fs/pipe.c Fri Mar 28 15:52:00 2008
> @@ -814,42 +814,9 @@
> .fasync = pipe_rdwr_fasync,
> };
>
> -static const struct file_operations read_pipe_fops = {
> - .llseek = no_llseek,
> - .read = do_sync_read,
> - .aio_read = pipe_read,
> - .write = bad_pipe_w,
> - .poll = pipe_poll,
> - .unlocked_ioctl = pipe_ioctl,
> - .open = pipe_read_open,
> - .release = pipe_read_release,
> - .fasync = pipe_read_fasync,
> -};
> -
> -static const struct file_operations write_pipe_fops = {
> - .llseek = no_llseek,
> - .read = bad_pipe_r,
> - .write = do_sync_write,
> - .aio_write = pipe_write,
> - .poll = pipe_poll,
> - .unlocked_ioctl = pipe_ioctl,
> - .open = pipe_write_open,
> - .release = pipe_write_release,
> - .fasync = pipe_write_fasync,
> -};
> -
> -static const struct file_operations rdwr_pipe_fops = {
> - .llseek = no_llseek,
> - .read = do_sync_read,
> - .aio_read = pipe_read,
> - .write = do_sync_write,
> - .aio_write = pipe_write,
> - .poll = pipe_poll,
> - .unlocked_ioctl = pipe_ioctl,
> - .open = pipe_rdwr_open,
> - .release = pipe_rdwr_release,
> - .fasync = pipe_rdwr_fasync,
> -};
> +#define read_pipe_fops read_fifo_fops
> +#define write_pipe_fops write_fifo_fops
> +#define rdwr_pipe_fops rdwr_fifo_fops
>
> struct pipe_inode_info * alloc_pipe_info(struct inode *inode)
> {
Well OK. But there's a risk that someone will go and modify
read_fifo_fops without realising that they're also modifying
read_pipe_fops.
So it'd be better to rename read_fifo_fops to (say) shared_read_fops
then do
#define read_pipe_fops shared_read_fops
#define read_fifo_fops shared_read_fops
no?
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