linux/include
Sebastian Andrzej Siewior 5efd2ea8c9 usb: core: buffer: smallest buffer should start at ARCH_DMA_MINALIGN
the following error pops up during "testusb -a -t 10"
| musb-hdrc musb-hdrc.1.auto: dma_pool_free buffer-128,	f134e000/be842000 (bad dma)
hcd_buffer_create() creates a few buffers, the smallest has 32 bytes of
size. ARCH_KMALLOC_MINALIGN is set to 64 bytes. This combo results in
hcd_buffer_alloc() returning memory which is 32 bytes aligned and it
might by identified by buffer_offset() as another buffer. This means the
buffer which is on a 32 byte boundary will not get freed, instead it
tries to free another buffer with the error message.

This patch fixes the issue by creating the smallest DMA buffer with the
size of ARCH_KMALLOC_MINALIGN (or 32 in case ARCH_KMALLOC_MINALIGN is
smaller). This might be 32, 64 or even 128 bytes. The next three pools
will have the size 128, 512 and 2048.
In case the smallest pool is 128 bytes then we have only three pools
instead of four (and zero the first entry in the array).
The last pool size is always 2048 bytes which is the assumed PAGE_SIZE /
2 of 4096. I doubt it makes sense to continue using PAGE_SIZE / 2 where
we would end up with 8KiB buffer in case we have 16KiB pages.
Instead I think it makes sense to have a common size(s) and extend them
if there is need to.
There is a BUILD_BUG_ON() now in case someone has a minalign of more than
128 bytes.

Cc: stable@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-01-09 10:21:31 -08:00
..
acpi Merge branches 'acpi-scan', 'acpi-utils' and 'acpi-pm' 2014-12-18 18:42:56 +01:00
asm-generic ARM: SoC/iommu configuration for 3.19 2014-12-16 14:53:01 -08:00
clocksource
crypto
drm Revert "drm/gem: Warn on illegal use of the dumb buffer interface v2" 2014-12-24 13:13:22 +10:00
dt-bindings Please consider pulling the clk framework changes toward 3.19. It is 2014-12-20 16:42:36 -08:00
keys
kvm arm/arm64: KVM: Require in-kernel vgic for the arch timers 2014-12-15 11:50:42 +01:00
linux usb: core: buffer: smallest buffer should start at ARCH_DMA_MINALIGN 2015-01-09 10:21:31 -08:00
math-emu
media
memory
misc
net Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-12-16 15:53:03 -08:00
pcmcia
ras
rdma IB/core: Implement support for MMU notifiers regarding on demand paging regions 2014-12-15 18:13:36 -08:00
rxrpc
scsi SCSI for-linus on 20141220 2014-12-20 13:42:57 -08:00
soc
sound sound updates for 3.19-rc1 2014-12-11 13:20:50 -08:00
target SCSI for-linus on 20141220 2014-12-20 13:42:57 -08:00
trace SCSI for-linus on 20141220 2014-12-20 13:42:57 -08:00
uapi Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending 2014-12-19 18:02:22 -08:00
video
xen
Kbuild