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Commit 550ddadc authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
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tty: hvc: hvc_write() may sleep 



Rework the hvc_write loop to drop and re-take the spinlock on each
iteration, add a cond_resched. Don't bother with an initial hvc_push
initially, which makes the logic simpler -- just do a hvc_push on
each time around the loop.

Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent cfb5946b

drivers/tty/hvc/hvc_console.c

+21 −15
Original line number Original line Diff line number Diff line
@@ -493,13 +493,12 @@ static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count 
	if (hp->port.count <= 0)

	if (hp->port.count <= 0)

		return -EIO;

		return -EIO;





	while (count > 0) {

		spin_lock_irqsave(&hp->lock, flags);

		spin_lock_irqsave(&hp->lock, flags);





	/* Push pending writes */

		rsize = hp->outbuf_size - hp->n_outbuf;

	if (hp->n_outbuf > 0)

		hvc_push(hp);





	while (count > 0 && (rsize = hp->outbuf_size - hp->n_outbuf) > 0) {

		if (rsize) {

			if (rsize > count)

			if (rsize > count)

				rsize = count;

				rsize = count;

			memcpy(hp->outbuf + hp->n_outbuf, buf, rsize);

			memcpy(hp->outbuf + hp->n_outbuf, buf, rsize);
@@ -507,10 +506,17 @@ static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count 
			buf += rsize;

			buf += rsize;

			hp->n_outbuf += rsize;

			hp->n_outbuf += rsize;

			written += rsize;

			written += rsize;

		hvc_push(hp);

		}

		}



		if (hp->n_outbuf > 0)

			hvc_push(hp);



		spin_unlock_irqrestore(&hp->lock, flags);

		spin_unlock_irqrestore(&hp->lock, flags);





		if (count)

			cond_resched();

	}



	/*

	/*

	 * Racy, but harmless, kick thread if there is still pending data.

	 * Racy, but harmless, kick thread if there is still pending data.

	 */

	 */