Re: [PATCH 6/7] tty/powerpc: introduce the ePAPR embedded hypervisor byte channel driver

On Thu, 19 May 2011 11:05:49 -0500
Timur Tabi [off-list ref] wrote:

Alan Cox wrote:

quoted

quoted

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+		/* Pass the received data to the tty layer.  Note that this
+		 * function calls tty_buffer_request_room(), so I'm not sure if
+		 * we should have also called tty_buffer_request_room().
+		 */
+		ret = tty_insert_flip_string(ttys, buffer, len);

quoted

You only need to request_room in advance if you can't handle the case
where the insert_flip_string returns less than you stuffed down it.

If tty_insert_flip_string() returns less than I stuffed down it, the characters
it didn't accept will be dropped.  That's because once I receive them, I have
nowhere else to put them.  I suppose I could implement a receive FIFO, but that
seems overkill.  If calling tty_buffer_request_room() ensures that
tty_insert_flip_string() always accepts all the characters, I would rather do that.

I was answering the question in the comment in the code...