diff options
| author | Mel Gorman <mel@csn.ul.ie> | 2010-03-02 22:24:19 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-04-01 15:58:31 -0700 |
| commit | d640f45411308c70e205d04938dfda94152738fb (patch) | |
| tree | d1ee2a3943ef00b6c454c45c70ad1b0da792468e /include/linux/tty.h | |
| parent | d560f99c9aafb9ebe1911541cf30d909819564eb (diff) | |
tty: Take a 256 byte padding into account when buffering below sub-page units
commit 352fa6ad16b89f8ffd1a93b4419b1a8f2259feab upstream.
The TTY layer takes some care to ensure that only sub-page allocations
are made with interrupts disabled. It does this by setting a goal of
"TTY_BUFFER_PAGE" to allocate. Unfortunately, while TTY_BUFFER_PAGE takes the
size of tty_buffer into account, it fails to account that tty_buffer_find()
rounds the buffer size out to the next 256 byte boundary before adding on
the size of the tty_buffer.
This patch adjusts the TTY_BUFFER_PAGE calculation to take into account the
size of the tty_buffer and the padding. Once applied, tty_buffer_alloc()
should not require high-order allocations.
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'include/linux/tty.h')
| -rw-r--r-- | include/linux/tty.h | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/include/linux/tty.h b/include/linux/tty.h index c396b449f77e..e9c57e9bb7f2 100644 --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -70,12 +70,13 @@ struct tty_buffer { /* * We default to dicing tty buffer allocations to this many characters - * in order to avoid multiple page allocations. We assume tty_buffer itself - * is under 256 bytes. See tty_buffer_find for the allocation logic this - * must match + * in order to avoid multiple page allocations. We know the size of + * tty_buffer itself but it must also be taken into account that the + * the buffer is 256 byte aligned. See tty_buffer_find for the allocation + * logic this must match */ -#define TTY_BUFFER_PAGE ((PAGE_SIZE - 256) / 2) +#define TTY_BUFFER_PAGE (((PAGE_SIZE - sizeof(struct tty_buffer)) / 2) & ~0xFF) struct tty_bufhead { |