Commit d6d9d17a authored by Andy Shevchenko's avatar Andy Shevchenko Committed by Greg Kroah-Hartman
Browse files

tty: tty_io: Switch to vmalloc() fallback in case of TTY_NO_WRITE_SPLIT 



When TTY_NO_WRITE_SPLIT is set and 64 KiB chunks are used, allow
vmalloc() fallback. Supply __GFP_RETRY_MAYFAIL to make kmalloc()
preferable over vmalloc() since we may want a better performance.

Note, both current users copy data to another buffer anyway, so
the type of our allocation doesn't affect their expectations.

Signed-off-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20211220133250.3070-1-andriy.shevchenko@linux.intel.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent e822b497

drivers/tty/tty_io.c

+3 −6
Original line number Original line Diff line number Diff line
@@ -169,7 +169,7 @@ static void free_tty_struct(struct tty_struct *tty) 
{

{

	tty_ldisc_deinit(tty);

	tty_ldisc_deinit(tty);

	put_device(tty->dev);

	put_device(tty->dev);

	kfree(tty->write_buf);

	kvfree(tty->write_buf);

	tty->magic = 0xDEADDEAD;

	tty->magic = 0xDEADDEAD;

	kfree(tty);

	kfree(tty);

}

}
@@ -986,9 +986,6 @@ static inline ssize_t do_tty_write( 
	 * layer has problems with bigger chunks. It will

	 * layer has problems with bigger chunks. It will

	 * claim to be able to handle more characters than

	 * claim to be able to handle more characters than

	 * it actually does.

	 * it actually does.

	 *

	 * FIXME: This can probably go away now except that 64K chunks

	 * are too likely to fail unless switched to vmalloc...

	 */

	 */

	chunk = 2048;

	chunk = 2048;

	if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))

	if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
@@ -1003,12 +1000,12 @@ static inline ssize_t do_tty_write( 
		if (chunk < 1024)

		if (chunk < 1024)

			chunk = 1024;

			chunk = 1024;





		buf_chunk = kmalloc(chunk, GFP_KERNEL);

		buf_chunk = kvmalloc(chunk, GFP_KERNEL | __GFP_RETRY_MAYFAIL);

		if (!buf_chunk) {

		if (!buf_chunk) {

			ret = -ENOMEM;

			ret = -ENOMEM;

			goto out;

			goto out;

		}

		}

		kfree(tty->write_buf);

		kvfree(tty->write_buf);

		tty->write_cnt = chunk;

		tty->write_cnt = chunk;

		tty->write_buf = buf_chunk;

		tty->write_buf = buf_chunk;

	}

	}

drivers/usb/class/cdc-acm.c

+0 −4
Original line number Original line Diff line number Diff line
@@ -685,10 +685,6 @@ static int acm_port_activate(struct tty_port *port, struct tty_struct *tty) 
	if (retval)

	if (retval)

		goto error_get_interface;

		goto error_get_interface;





	/*

	 * FIXME: Why do we need this? Allocating 64K of physically contiguous

	 * memory is really nasty...

	 */

	set_bit(TTY_NO_WRITE_SPLIT, &tty->flags);

	set_bit(TTY_NO_WRITE_SPLIT, &tty->flags);

	acm->control->needs_remote_wakeup = 1;

	acm->control->needs_remote_wakeup = 1;