[PATCH 2/7] tty: Take a 256 byte padding into account when buffering below sub-page units
in [Kernel]
|
Prev: [PATCH 12/12] driver core: numa: fix BUILD_BUG_ON for node_read_distance
Next: [PATCH][RESEND] x86: add HPET-quirk for nVidia MCP61 LPC Bridge (10de:03e0)
From: Greg Kroah-Hartman on 19 Mar 2010 11:30 From: Mel Gorman <mel(a)csn.ul.ie> 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(a)csn.ul.ie> Cc: stable <stable(a)kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh(a)suse.de> --- 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 568369a..593228a 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 { -- 1.7.0.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |