Commit 917e2fd2 authored Sep 25, 2018 by Anton Ivanov Committed by Richard Weinberger Oct 29, 2018

um: Make line/tty semantics use true write IRQ



This fixes a long standing bug where large amounts of output
could freeze the tty (most commonly seen on stdio console).
While the bug has always been there it became more pronounced
after moving to the new interrupt controller.

The line semantics are now changed to have true IRQ write
semantics which should further improve the tty/line subsystem
stability and performance

Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

parent 59fdf91d

arch/um/drivers/line.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -261,7 +261,7 @@ static irqreturn_t line_write_interrupt(int irq, void *data)
		if (err == 0) {
		spin_unlock(&line->lock);
		return IRQ_NONE;
		} else if (err < 0) {
		} else if ((err < 0) && (err != -EAGAIN)) {
		line->head = line->buffer;
		line->tail = line->buffer;
		}
		@@ -284,7 +284,7 @@ int line_setup_irq(int fd, int input, int output, struct line line, void data)
		if (err)
		return err;
		if (output)
		err = um_request_irq(driver->write_irq, fd, IRQ_NONE,
		err = um_request_irq(driver->write_irq, fd, IRQ_WRITE,
		line_write_interrupt, IRQF_SHARED,
		driver->write_irq_name, data);
		return err;