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

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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: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20211220133250.3070-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Andy Shevchenko 2021-12-20 15:32:50 +02:00 committed by Greg Kroah-Hartman
parent e822b4973f
commit d6d9d17aba
2 changed files with 3 additions and 10 deletions
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9
drivers/tty/tty_io.c
View file

@ -169,7 +169,7 @@ static void free_tty_struct(struct tty_struct *tty)
{
tty_ldisc_deinit(tty);
put_device(tty->dev);
kfree(tty->write_buf);
kvfree(tty->write_buf);
tty->magic = 0xDEADDEAD;
kfree(tty);
}
@ -986,9 +986,6 @@ static inline ssize_t do_tty_write(
* layer has problems with bigger chunks. It will
* claim to be able to handle more characters than
* 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;
if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
@ -1003,12 +1000,12 @@ static inline ssize_t do_tty_write(
if (chunk < 1024)
chunk = 1024;
buf_chunk = kmalloc(chunk, GFP_KERNEL);
buf_chunk = kvmalloc(chunk, GFP_KERNEL | __GFP_RETRY_MAYFAIL);
if (!buf_chunk) {
ret = -ENOMEM;
goto out;
}
kfree(tty->write_buf);
kvfree(tty->write_buf);
tty->write_cnt = chunk;
tty->write_buf = buf_chunk;
}

4
drivers/usb/class/cdc-acm.c
View file

@ -685,10 +685,6 @@ static int acm_port_activate(struct tty_port *port, struct tty_struct *tty)
if (retval)
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);
acm->control->needs_remote_wakeup = 1;