linux-kernel - Re: linux-next: manual merge of the tty tree with the tree

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Message-ID: <4AA58160.7080908@skyrush.com>
Date:	Mon, 07 Sep 2009 15:55:44 -0600
From:	Joe Peterson <joe@...rush.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
CC:	Stephen Rothwell <sfr@...b.auug.org.au>, Greg KH <greg@...ah.com>,
	linux-next@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: linux-next: manual merge of the tty tree with the  tree

Linus Torvalds wrote:
> Hmm. I think that the "honor opost flag for echoes" patch is actually 
> wrong.
> 
> We check O_OPOST() in the _caller_ for the regular write case, and that
> test actually looks like this:
> 
> 	if (O_OPOST(tty) && !(test_bit(TTY_HW_COOK_OUT, &tty->flags))) {
> 
> so at a minimum, if we add it to process_output() we should likely add it 
> in the same format. But if we need that test, I'd rather do it in the 
> caller anyway, like we already do for regular writes.

Yes, very true.  The old opost() function also contained the O_OPOST
check (i.e. causing a double check for normal writes), and you are right
that we should not reintroduce it (and it makes sense for the caller to
check it).

There is only the one case in which the O_OPOST check is needed before
calling do_output_char() (in process_echoes()), so we could just inline
the test there.  Take a look at my new attached patch (untested also).
I'll test and resubmit, assuming there are no objections.

					-Thanks, Joe

View attachment "n_tty-honor-opost-flag-for-echoes.patch" of type "text/plain" (2103 bytes)