[PATCH 5/5] kfifo: log based kfifo API
The current kfifo API take the kfifo size as input, while it rounds
_down_ the size to power of 2 at __kfifo_alloc. This may introduce
potential issue.
Take the code at drivers/hid/hid-logitech-dj.c as example:
if (kfifo_alloc(djrcv_dev-notif_fifo,
DJ_MAX_NUMBER_NOTIFICATIONS * sizeof(struct dj_report),
GFP_KERNEL)) {
Where, DJ_MAX_NUMBER_NOTIFICATIONS is 8, and sizeo of(struct dj_report)
is 15.
Which means it wants to allocate a kfifo buffer which can store 8
dj_report entries at once. The expected kfifo buffer size would be
8 * 15 = 120 then. While, in the end, __kfifo_alloc will turn the
size to rounddown_power_of_2(120) = 64, and then allocate a buf
with 64 bytes, which I don't think this is the original author want.
With the new log API, we can do like following:
int kfifo_size_order = order_base_2(DJ_MAX_NUMBER_NOTIFICATIONS *
sizeof(struct dj_report));
if (kfifo_alloc(djrcv_dev-notif_fifo, kfifo_size_order, GFP_KERNEL)) {
This make sure we will allocate enough kfifo buffer for holding
DJ_MAX_NUMBER_NOTIFICATIONS dj_report entries.
Cc: Stefani Seibold stef...@seibold.net
Cc: Andrew Morton a...@linux-foundation.org
Cc: linux-o...@vger.kernel.org
Cc: linuxppc-...@lists.ozlabs.org
Cc: platform-driver-...@vger.kernel.org
Cc: linux-in...@vger.kernel.org
Cc: linux-...@vger.kernel.org
Cc: linux-r...@vger.kernel.org
Cc: linux-media@vger.kernel.org
Cc: linux-...@vger.kernel.org
Cc: linux-...@lists.infradead.org
Cc: libertas-...@lists.infradead.org
Cc: linux-wirel...@vger.kernel.org
Cc: net...@vger.kernel.org
Cc: linux-...@vger.kernel.org
Cc: open-is...@googlegroups.com
Cc: linux-s...@vger.kernel.org
Cc: de...@driverdev.osuosl.org
Cc: linux-ser...@vger.kernel.org
Cc: linux-...@vger.kernel.org
Cc: linux...@kvack.org
Cc: d...@vger.kernel.org
Cc: linux-s...@vger.kernel.org
Signed-off-by: Yuanhan Liu yuanhan@linux.intel.com
---
arch/arm/plat-omap/Kconfig |2 +-
arch/arm/plat-omap/mailbox.c|6 +++-
arch/powerpc/sysdev/fsl_rmu.c |2 +-
drivers/char/sonypi.c |9 ---
drivers/hid/hid-logitech-dj.c |7 +++--
drivers/iio/industrialio-event.c|2 +-
drivers/iio/kfifo_buf.c |3 +-
drivers/infiniband/hw/cxgb3/cxio_resource.c |8 --
drivers/media/i2c/cx25840/cx25840-ir.c |9 +--
drivers/media/pci/cx23885/cx23888-ir.c |9 +--
drivers/media/pci/meye/meye.c |6 +---
drivers/media/pci/meye/meye.h |2 +
drivers/media/rc/ir-raw.c |7 +++--
drivers/memstick/host/r592.h|2 +-
drivers/mmc/card/sdio_uart.c|4 ++-
drivers/mtd/sm_ftl.c|5 +++-
drivers/net/wireless/libertas/main.c|4 ++-
drivers/net/wireless/rt2x00/rt2x00dev.c |5 +--
drivers/pci/pcie/aer/aerdrv_core.c |3 +-
drivers/platform/x86/fujitsu-laptop.c |5 ++-
drivers/platform/x86/sony-laptop.c |6 ++--
drivers/rapidio/devices/tsi721.c|5 ++-
drivers/scsi/libiscsi_tcp.c |6 +++-
drivers/staging/omapdrm/omap_plane.c|5 +++-
drivers/tty/n_gsm.c |4 ++-
drivers/tty/nozomi.c|5 +--
drivers/tty/serial/ifx6x60.c|2 +-
drivers/tty/serial/ifx6x60.h|3 +-
drivers/tty/serial/kgdb_nmi.c |7 +++--
drivers/usb/host/fhci.h |4 ++-
drivers/usb/serial/cypress_m8.c |4 +-
drivers/usb/serial/io_ti.c |4 +-
drivers/usb/serial/ti_usb_3410_5052.c |7 +++--
drivers/usb/serial/usb-serial.c |2 +-
include/linux/kfifo.h | 31 +--
include/linux/rio.h |1 +
include/media/lirc_dev.h|4 ++-
kernel/kfifo.c |9 +--
mm/memory-failure.c |3 +-
net/dccp/probe.c|6 +++-
net/sctp/probe.c|6 +++-
samples/kfifo/bytestream-example.c |8 +++---
samples/kfifo/dma-example.c |5 ++-
samples/kfifo/inttype-example.c |7 +++--
samples/kfifo/record-example.c |6 ++--
45 files changed, 142 insertions(+), 108 deletions(-)
diff --git a/arch/arm/plat-omap/Kconfig b/arch/arm/plat-omap/Kconfig
index 665870d..7eda02c 100644
--- a/arch/arm/plat-omap/Kconfig
+++ b/arch/arm/plat-omap/Kconfig
@@ -124,7 +124,7 @@ config OMAP_MBOX_FWK
DSP, IVA1.0 and IVA2 in OMAP1/2/3.
config OMAP_MBOX_KFIFO_SIZE
- int Mailbox kfifo default buffer size (bytes)
+ int Mailbox kfifo default buffer size (bytes,
Re: [PATCH 5/5] kfifo: log based kfifo API
Hi Yuanhan,
On Tue, Jan 08, 2013 at 10:57:53PM +0800, Yuanhan Liu wrote:
The current kfifo API take the kfifo size as input, while it rounds
_down_ the size to power of 2 at __kfifo_alloc. This may introduce
potential issue.
Take the code at drivers/hid/hid-logitech-dj.c as example:
if (kfifo_alloc(djrcv_dev-notif_fifo,
DJ_MAX_NUMBER_NOTIFICATIONS * sizeof(struct dj_report),
GFP_KERNEL)) {
Where, DJ_MAX_NUMBER_NOTIFICATIONS is 8, and sizeo of(struct dj_report)
is 15.
Which means it wants to allocate a kfifo buffer which can store 8
dj_report entries at once. The expected kfifo buffer size would be
8 * 15 = 120 then. While, in the end, __kfifo_alloc will turn the
size to rounddown_power_of_2(120) = 64, and then allocate a buf
with 64 bytes, which I don't think this is the original author want.
With the new log API, we can do like following:
int kfifo_size_order = order_base_2(DJ_MAX_NUMBER_NOTIFICATIONS *
sizeof(struct dj_report));
if (kfifo_alloc(djrcv_dev-notif_fifo, kfifo_size_order, GFP_KERNEL)) {
This make sure we will allocate enough kfifo buffer for holding
DJ_MAX_NUMBER_NOTIFICATIONS dj_report entries.
Why don't you simply change __kfifo_alloc to round the allocation up
instead of down?
Thanks.
--
Dmitry
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Re: [PATCH 5/5] kfifo: log based kfifo API
Dmitry Torokhov dmitry.torok...@gmail.com wrote:
Hi Yuanhan,
On Tue, Jan 08, 2013 at 10:57:53PM +0800, Yuanhan Liu wrote:
The current kfifo API take the kfifo size as input, while it rounds
_down_ the size to power of 2 at __kfifo_alloc. This may introduce
potential issue.
Take the code at drivers/hid/hid-logitech-dj.c as example:
if (kfifo_alloc(djrcv_dev-notif_fifo,
DJ_MAX_NUMBER_NOTIFICATIONS * sizeof(struct
dj_report),
GFP_KERNEL)) {
Where, DJ_MAX_NUMBER_NOTIFICATIONS is 8, and sizeo of(struct
dj_report)
is 15.
Which means it wants to allocate a kfifo buffer which can store 8
dj_report entries at once. The expected kfifo buffer size would be
8 * 15 = 120 then. While, in the end, __kfifo_alloc will turn the
size to rounddown_power_of_2(120) = 64, and then allocate a buf
with 64 bytes, which I don't think this is the original author want.
With the new log API, we can do like following:
int kfifo_size_order = order_base_2(DJ_MAX_NUMBER_NOTIFICATIONS *
sizeof(struct dj_report));
if (kfifo_alloc(djrcv_dev-notif_fifo, kfifo_size_order,
GFP_KERNEL)) {
This make sure we will allocate enough kfifo buffer for holding
DJ_MAX_NUMBER_NOTIFICATIONS dj_report entries.
Why don't you simply change __kfifo_alloc to round the allocation up
instead of down?
Thanks.
--
Dmitry
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in
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Hi Dmitry,
I agree. I don't see the benefit in pushing up the change to a kfifo internal
decision/problem to many different places in the kernel.
Regards,
Andy
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Re: [PATCH 5/5] kfifo: log based kfifo API
On Tue, Jan 08, 2013 at 10:16:46AM -0800, Dmitry Torokhov wrote:
Hi Yuanhan,
On Tue, Jan 08, 2013 at 10:57:53PM +0800, Yuanhan Liu wrote:
The current kfifo API take the kfifo size as input, while it rounds
_down_ the size to power of 2 at __kfifo_alloc. This may introduce
potential issue.
Take the code at drivers/hid/hid-logitech-dj.c as example:
if (kfifo_alloc(djrcv_dev-notif_fifo,
DJ_MAX_NUMBER_NOTIFICATIONS * sizeof(struct
dj_report),
GFP_KERNEL)) {
Where, DJ_MAX_NUMBER_NOTIFICATIONS is 8, and sizeo of(struct dj_report)
is 15.
Which means it wants to allocate a kfifo buffer which can store 8
dj_report entries at once. The expected kfifo buffer size would be
8 * 15 = 120 then. While, in the end, __kfifo_alloc will turn the
size to rounddown_power_of_2(120) = 64, and then allocate a buf
with 64 bytes, which I don't think this is the original author want.
With the new log API, we can do like following:
int kfifo_size_order = order_base_2(DJ_MAX_NUMBER_NOTIFICATIONS *
sizeof(struct dj_report));
if (kfifo_alloc(djrcv_dev-notif_fifo, kfifo_size_order, GFP_KERNEL)) {
This make sure we will allocate enough kfifo buffer for holding
DJ_MAX_NUMBER_NOTIFICATIONS dj_report entries.
Why don't you simply change __kfifo_alloc to round the allocation up
instead of down?
Hi Dmitry,
Yes, it would be neat and that was my first reaction as well. I then
sent out a patch, but it was NACKed by Stefani(the original kfifo
author). Here is the link:
https://lkml.org/lkml/2012/10/26/144
Then Stefani proposed to change the API to take log of size as input to
root fix this kind of issues. And here it is.
Thanks.
--yliu
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