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Jon Hunter 5ca7c109e8 of: dma: fix potential deadlock when requesting a slave channel 
In the latest version of the OF dma handlers I added support (rather hastily)
to exhaustively search for an available dma slave channel, for the use-case
where we have alternative slave channels that can be used. In the current
implementation a deadlock scenario can occur causing the CPU to loop forever.
The scenario is as follows ...

1. There are alternative channels avaialble
2. The first channel that is found by calling of_dma_find_channel() is not
   available and so the call to the xlate function returns NULL. In this case
   we will call of_dma_find_channel() again but we will return the same channel
   that we found the first time and hence, again the xlate will return NULL and
   we will loop here forever.

Fix this potential deadlock by just using a single for-loop and not a for-loop
nested in a do-while loop. This change also replaces the function
of_dma_find_channel() with of_dma_match_channel() which performs a simple check
to see if a DMA channel matches the name specified.

I have tested this implementation on an OMAP4 panda board by adding a dummy
DMA specifier, that will cause the xlate function to return NULL, to the
beginning of a list of DMA specifiers for a DMA client.

Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Benoit Cousson <b-cousson@ti.com>
Cc: Stephen Warren <swarren@nvidia.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Rob Herring <rob.herring@calxeda.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Vinod Koul <vinod.koul@intel.com>
Cc: Dan Williams <djbw@fb.com>

Signed-off-by: Jon Hunter <jon-hunter@ti.com>
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>
 		2013-01-07 22:05:00 -08:00
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acpi Merge branch 'x86-acpi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-12-14 10:03:23 -08:00
amba Merge tag 'tegra-for-3.8-fixes-for-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/swarren/linux-tegra into fixes 2012-12-17 10:04:27 -08:00
ata 1) More ACPI fixes 2012-12-15 12:37:18 -08:00
atm solos-pci: double lock in geos_gpio_store() 2012-12-21 13:14:00 -08:00
auxdisplay
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base vfs: turn is_dir argument to kern_path_create into a lookup_flags arg 2012-12-20 18:50:02 -05:00
bcma MTD pull for 3.8 2012-12-19 12:47:41 -08:00
block Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client 2012-12-20 14:00:13 -08:00
bluetooth Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2012-12-12 18:07:07 -08:00
bus ARM: OMAP: Fix drivers to depend on omap for internal devices 2012-12-16 15:23:37 -08:00
cdrom
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char Some nice cleanups, and even a patch my wife did as a "live" demo for 2012-12-20 08:37:05 -08:00
clk MTD pull for 3.8 2012-12-19 12:47:41 -08:00
clocksource ARM: arm-soc: Updates for Marvell mvebu/kirkwood 2012-12-14 14:54:26 -08:00
connector
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cpufreq ACPI and power management updates for 3.8-rc1 2012-12-11 12:45:35 -08:00
cpuidle ARM: arm-soc: SoC updates for 3.8 2012-12-12 12:05:15 -08:00
crypto Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc 2012-12-18 09:58:09 -08:00
dca
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devfreq Merge branch 'pm-devfreq' 2012-12-07 23:13:36 +01:00
dio
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dma ioat: add missing DMA unmap to ioat_dma_self_test() 2013-01-07 22:04:58 -08:00
edac Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus 2012-12-14 14:27:45 -08:00
eisa
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extcon
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firewire Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2012-12-13 12:00:02 -08:00
firmware drivers/firmware/dmi_scan.c: fetch dmi version from SMBIOS if it exists 2012-12-20 17:40:19 -08:00
gpio gpio/mvebu-gpio: Make mvebu-gpio depend on OF_CONFIG 2012-12-19 22:15:14 +00:00
gpu Revert "drm: tegra: protect DC register access with mutex" 2012-12-30 21:58:20 +10:00
hid Merge branch 'v4l_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media 2012-12-13 19:22:22 -08:00
hsi
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hv
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hwmon hwmon: (emc6w201) Fix DIV_ROUND_CLOSEST problem with unsigned divisors 2012-12-22 02:16:40 -08:00
hwspinlock
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i2c i2c: remove __dev* attributes from subsystem 2012-12-22 20:13:45 +01:00
ide
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idle
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iio This is the MFD patch set for the 3.8 merge window. 2012-12-16 18:55:20 -08:00
infiniband Second batch of InfiniBand/RDMA changes for 3.8: 2012-12-21 16:40:26 -08:00
input Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-12-19 12:56:42 -08:00
iommu IOMMU Updates for Linux v3.8 2012-12-20 10:07:25 -08:00
ipack TTY/Serial merge for 3.8-rc1 2012-12-11 14:08:47 -08:00
irqchip ARM: arm-soc: Device-tree updates, take 2 2012-12-14 14:42:53 -08:00
isdn mISDN: fix race in timer canceling on module unloading 2012-12-14 13:14:07 -05:00
leds leds: leds-gpio: set devm_gpio_request_one() flags param correctly 2013-01-02 17:58:41 -08:00
lguest lguest: fix typo 2012-12-18 15:19:06 +10:30
macintosh Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc 2012-12-18 09:58:09 -08:00
md Miscellaneous device-mapper fixes, cleanups and performance improvements. 2012-12-21 17:08:06 -08:00
media ARM: arm-soc: late cleanups for omap 2012-12-30 09:59:21 -08:00
memory
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memstick
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message drivers/message/fusion/mptscsih.c: missing break 2012-12-18 15:02:12 -08:00
mfd ARM: arm-soc fixes for 3.8 2012-12-20 07:21:54 -08:00
misc carma-fpga: pass correct flags to ->device_prep_dma_memcpy() 2013-01-07 22:05:00 -08:00
mmc This is the MFD patch set for the 3.8 merge window. 2012-12-16 18:55:20 -08:00
mtd mtd: fsmc_nand: add missing DMA unmap to dma_xfer() 2013-01-07 22:04:59 -08:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2012-12-27 10:40:30 -08:00
nfc
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nubus
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of of: dma: fix potential deadlock when requesting a slave channel 2013-01-07 22:05:00 -08:00
oprofile
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parisc
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parport
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pci PCI: Reduce Ricoh 0xe822 SD card reader base clock frequency to 50MHz 2012-12-26 10:43:06 -07:00
pcmcia ARM: arm-soc: Header cleanups 2012-12-12 11:45:16 -08:00
pinctrl pinctrl: exynos5440/samsung: Staticize pcfgs 2012-12-18 19:00:25 -08:00
platform Corentin has moved 2012-12-17 17:15:14 -08:00
pnp Driver core updates for 3.8-rc1 2012-12-11 13:13:55 -08:00
power ARM: arm-soc: late cleanups for omap 2012-12-30 09:59:21 -08:00
pps
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ps3
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ptp Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2012-12-12 18:07:07 -08:00
pwm pwm: Changes for v3.8-rc1 2012-12-19 08:19:07 -08:00
rapidio Driver core updates for 3.8-rc1 2012-12-11 13:13:55 -08:00
regulator Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2012-12-13 12:00:02 -08:00
remoteproc Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2012-12-13 12:00:02 -08:00
rpmsg virtio: rpmsg: make it clear that virtqueue_add_buf() no longer returns > 0 2012-12-18 15:20:36 +10:30
rtc revert "rtc: recycle id when unloading a rtc driver" 2012-12-20 17:40:20 -08:00
s390 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux 2012-12-13 14:20:19 -08:00
sbus
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scsi Second batch of InfiniBand/RDMA changes for 3.8: 2012-12-21 16:40:26 -08:00
sfi
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sh
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sn
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spi spi/sh-hspi: fix return value check in hspi_probe(). 2012-12-19 15:11:41 +00:00
ssb Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus 2012-12-14 14:27:45 -08:00
staging Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2012-12-17 15:44:47 -08:00
target Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending 2012-12-15 14:25:10 -08:00
tc
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thermal Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2012-12-13 12:00:02 -08:00
tty Merge branch 'omap-for-v3.8/fixes-for-merge-window' into omap-for-v3.8/fixes-for-merge-window-v2 2012-12-16 11:28:10 -08:00
uio ARM: arm-soc: SoC updates for 3.8 2012-12-12 12:05:15 -08:00
usb usb: musb: use io{read,write}*_rep accessors 2012-12-17 17:15:13 -08:00
uwb
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vfio vfio-pci: Enable device before attempting reset 2012-12-07 13:43:51 -07:00
vhost Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending 2012-12-15 14:25:10 -08:00
video backlight: locomolcd: fix checkpatch error and warning 2012-12-18 15:02:11 -08:00
virt Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc 2012-12-18 09:58:09 -08:00
virtio Some nice cleanups, and even a patch my wife did as a "live" demo for 2012-12-20 08:37:05 -08:00
vlynq
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vme
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w1 ARM: OMAP: Fix drivers to depend on omap for internal devices 2012-12-16 15:23:37 -08:00
watchdog watchdog: twl4030_wdt: add DT support 2013-01-02 12:07:05 +01:00
xen Feature: 2012-12-16 17:39:14 -08:00
zorro
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Kconfig
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Makefile
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