Fix to a problem observed when losing a FIN segment that does not
contain data. In such situations, TLP is unable to recover from
*any* tail loss and instead adds at least PTO ms to the
retransmission process, i.e., RTO = RTO + PTO.
Signed-off-by: Per Hurtig <per.hurtig@kau.se>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Nandita Dukkipati <nanditad@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Fugang Duan says:
====================
net: fec: Enable Software TSO to improve the tx performance
Add SG and software TSO support for FEC.
This feature allows to improve outbound throughput performance.
Tested on imx6dl sabresd board, running iperf tcp tests shows:
* 82% improvement comparing with NO SG & TSO patch
$ ethtool -K eth0 sg on
$ ethtool -K eth0 tso on
[ 3] local 10.192.242.108 port 35388 connected with 10.192.242.167 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0- 3.0 sec 181 MBytes 506 Mbits/sec
* cpu loading is 30%
$ ethtool -K eth0 sg off
$ ethtool -K eth0 tso off
[ 3] local 10.192.242.108 port 52618 connected with 10.192.242.167 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0- 3.0 sec 99.5 MBytes 278 Mbits/sec
FEC HW support IP header and TCP/UDP hw checksum, support multi buffer descriptor transfer
one frame, but don't support HW TSO. And imx6q/dl SOC FEC Gbps speed has HW bus Bandwidth
limitation (400Mbps ~ 700Mbps), imx6sx SOC FEC Gbps speed has no HW bandwidth limitation.
The patch set just enable TSO feature, which is done following the mv643xx_eth driver.
Test result analyze:
imx6dl sabresd board: there have 82% improvement, since imx6dl FEC HW has bandwidth limitation,
the performance with SW TSO is a milestone.
Addition test:
imx6sx sdb board:
upstream still don't support imx6sx due to some patches being upstream... they use same FEC IP.
Use the SW TSO patches test imx6sx sdb board in internal kernel tree:
No SW TSO patch: tx bandwidth 840Mbps, cpu loading is 100%.
SW TSO patch: tx bandwidth 942Mbps, cpu loading is 65%.
It means the patch set have great improvement for imx6sx FEC performance.
V2:
* From Frank Li's suggestion:
Change the API "fec_enet_txdesc_entry_free" name to "fec_enet_get_free_txdesc_num".
* Summary David Laight and Eric Dumazet's thoughts:
RX BD entry number change to 256.
* From ezequiel's suggestion:
Follow the latest TSO fixes from his solution to rework the queue stop/wake-up.
Avoid unmapping the TSO header buffers.
* From Eric Dumazet's suggestion:
Avoid more bytes copy, just copying the unaligned part of the payload into first
descriptor. The suggestion will bring more complex for the driver, and imx6dl FEC
DMA need 16 bytes alignment, but cpu loading is not problem that cpu loading is
30%, the current performance is so better. Later chip like imx6sx Gigbit FEC DMA
support byte alignment, so there don't exist memory copy. So, the V2 version drop
the suggestion.
Anyway, thanks for Eric's response and suggestion.
V3:
* From David Laight's feedback:
Decide to drop RX BD entry number change for the SW TSO patch set.
I will generate one separate patch to increase RX BDs entry for interrupt coalescing feature which
will be supported in my later patch set.
V4:
* From David Laight's feedback:
Remove the conditional in .fec_enet_get_bd_index().
V5:
* Patch #4 update:
From David Laight's feedback:
"expect fec_enet_get_free_txdesc_num() to return one less than it does currently."
Change the function:
Return space available, 0..size-1. it always leave one free entry. Which is same as linux circ_buf.
Thanks for Eric and ezequiel's help and idea.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
Add software TSO support for FEC.
This feature allows to improve outbound throughput performance.
Tested on imx6dl sabresd board, running iperf tcp tests shows:
- 16.2% improvement comparing with FEC SG patch
- 82% improvement comparing with NO SG & TSO patch
$ ethtool -K eth0 tso on
$ iperf -c 10.192.242.167 -t 3 &
[ 3] local 10.192.242.108 port 35388 connected with 10.192.242.167 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0- 3.0 sec 181 MBytes 506 Mbits/sec
During the testing, CPU loading is 30%.
Since imx6dl FEC Bandwidth is limited to SOC system bus bandwidth, the
performance with SW TSO is a milestone.
CC: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
CC: Eric Dumazet <eric.dumazet@gmail.com>
CC: David Laight <David.Laight@ACULAB.COM>
CC: Li Frank <B20596@freescale.com>
Signed-off-by: Fugang Duan <B38611@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add Scatter/gather support for FEC.
This feature allows to improve outbound throughput performance.
Tested on imx6dl sabresd board:
Running iperf tests shows a 55.4% improvement.
$ ethtool -K eth0 sg off
$ iperf -c 10.192.242.167 -t 3 &
[ 3] local 10.192.242.108 port 52618 connected with 10.192.242.167 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0- 3.0 sec 99.5 MBytes 278 Mbits/sec
$ ethtool -K eth0 sg on
$ iperf -c 10.192.242.167 -t 3 &
[ 3] local 10.192.242.108 port 52617 connected with 10.192.242.167 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0- 3.0 sec 154 MBytes 432 Mbits/sec
CC: Li Frank <B20596@freescale.com>
Signed-off-by: Fugang Duan <B38611@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
In order to support SG, software TSO, let's increase BD entry number.
CC: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
CC: Eric Dumazet <eric.dumazet@gmail.com>
CC: David Laight <David.Laight@ACULAB.COM>
Signed-off-by: Fugang Duan <B38611@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
In order to enhance the code readable, let's factorize the
feature list.
Signed-off-by: Fugang Duan <B38611@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
IP header checksum is calcalated by network layer in default.
To support software TSO, it is better to use HW calculate the
IP header checksum.
FEC hw checksum feature request the checksum field in frame
is zero, otherwise the calculative CRC is not correct.
For segmentated TCP packet, HW calculate the IP header checksum again,
it doesn't bring any impact. For SW TSO, HW calculated checksum bring
better performance.
Signed-off-by: Fugang Duan <B38611@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Make the code more readable and easy to support other features like
SG, TSO, moving the common transmit function to one api.
And the patch also factorize the getting BD index to it own function.
CC: David Laight <David.Laight@ACULAB.COM>
Signed-off-by: Fugang Duan <B38611@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Some fields in "struct net_bridge" aren't available when compiling the
kernel without IPv6 support. Therefore adding a check/macro to skip the
complaining code sections in that case.
Introduced by 2cd4143192
("bridge: memorize and export selected IGMP/MLD querier port")
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Linus Lüssing <linus.luessing@web.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
"New smatch warnings:
net/bridge/br_multicast.c:1368 br_ip6_multicast_query() error:
we previously assumed 'group' could be null (see line 1349)"
In the rare (sort of broken) case of a query having a Maximum
Response Delay of zero, we could create a potential null pointer
dereference.
Fixing this by skipping the multicast specific MLD Query parsing again
if no multicast group address is available.
Introduced by dc4eb53a99
("bridge: adhere to querier election mechanism specified by RFCs")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Linus Lüssing <linus.luessing@web.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
With some specific configuration (VT6105M on Soekris 5510 and depending
on the device at the other end), fragmented packets were not transmitted
when forcing 100 full-duplex with autoneg disable.
This fix now write full-duplex chips register when forcing full or
half-duplex not only when autoneg is enable.
Signed-off-by: François Cachereul <f.cachereul@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
Pull vfs updates from Al Viro:
"This the bunch that sat in -next + lock_parent() fix. This is the
minimal set; there's more pending stuff.
In particular, I really hope to get acct.c fixes merged this cycle -
we need that to deal sanely with delayed-mntput stuff. In the next
pile, hopefully - that series is fairly short and localized
(kernel/acct.c, fs/super.c and fs/namespace.c). In this pile: more
iov_iter work. Most of prereqs for ->splice_write with sane locking
order are there and Kent's dio rewrite would also fit nicely on top of
this pile"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (70 commits)
lock_parent: don't step on stale ->d_parent of all-but-freed one
kill generic_file_splice_write()
ceph: switch to iter_file_splice_write()
shmem: switch to iter_file_splice_write()
nfs: switch to iter_splice_write_file()
fs/splice.c: remove unneeded exports
ocfs2: switch to iter_file_splice_write()
->splice_write() via ->write_iter()
bio_vec-backed iov_iter
optimize copy_page_{to,from}_iter()
bury generic_file_aio_{read,write}
lustre: get rid of messing with iovecs
ceph: switch to ->write_iter()
ceph_sync_direct_write: stop poking into iov_iter guts
ceph_sync_read: stop poking into iov_iter guts
new helper: copy_page_from_iter()
fuse: switch to ->write_iter()
btrfs: switch to ->write_iter()
ocfs2: switch to ->write_iter()
xfs: switch to ->write_iter()
...
Yuval Mintz says:
====================
bnx2x: Bug fixes patch series
This patch series contains various bug fixes - 2 link related fixes,
one sriov-related issue and an additional fix for a theoretical bug
on new boards.
Please consider applying these patches to `net'.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
A malicious VF might try to starve the other VFs & PF by creating
contineous doorbell floods. In order to negate this, HW has a threshold of
doorbells per client, which will stop the client doorbells from arriving
if crossed.
The threshold currently configured for VFs is too low - under extreme traffic
scenarios, it's possible for a VF to reach the threshold and thus for its
fastpath to stop working.
Signed-off-by: Ariel Elior <ariel.elior@qlogic.com>
Signed-off-by: Yuval Mintz <yuval.mintz@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
If L2FW utilized by the UNDI driver has the same version number as that
of the regular FW, a driver loading after UNDI and receiving an uncommon
answer from management will mistakenly assume the loaded FW matches its
own requirement and try to exist the flow via FLR.
Signed-off-by: Yuval Mintz <yuval.mintz@qlogic.com>
Signed-off-by: Ariel Elior <ariel.elior@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Set the phy access mode even in case of link-flap avoidance.
Signed-off-by: Yaniv Rosner <yaniv.rosner@qlogic.com>
Signed-off-by: Yuval Mintz <yuval.mintz@qlogic.com>
Signed-off-by: Ariel Elior <ariel.elior@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This avoids clearing the RX polarity setting in KR mode when polarity lane
is swapped, as otherwise this will result in failed link.
Signed-off-by: Yaniv Rosner <yaniv.rosner@qlogic.com>
Signed-off-by: Yuval Mintz <yuval.mintz@qlogic.com>
Signed-off-by: Ariel Elior <ariel.elior@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Consider the scenario:
For a TCP-style socket, while processing the COOKIE_ECHO chunk in
sctp_sf_do_5_1D_ce(), after it has passed a series of sanity check,
a new association would be created in sctp_unpack_cookie(), but afterwards,
some processing maybe failed, and sctp_association_free() will be called to
free the previously allocated association, in sctp_association_free(),
sk_ack_backlog value is decremented for this socket, since the initial
value for sk_ack_backlog is 0, after the decrement, it will be 65535,
a wrap-around problem happens, and if we want to establish new associations
afterward in the same socket, ABORT would be triggered since sctp deem the
accept queue as full.
Fix this issue by only decrementing sk_ack_backlog for associations in
the endpoint's list.
Fix-suggested-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Xufeng Zhang <xufeng.zhang@windriver.com>
Acked-by: Daniel Borkmann <dborkman@redhat.com>
Acked-by: Vlad Yasevich <vyasevich@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Use devm_hwmon_device_register_with_groups instead of
the old-style manual attributes and hwmon device registration.
Also, unroll the attribute group macros for better code
readability.
Signed-off-by: Pawel Moll <pawel.moll@arm.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Move atxp1_id and atxp1_driver to proper place to avoid forward declaration.
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Add support for Sensirion SHTC1 and compatible temperature and humidity
sensors.
Signed-off-by: Tomas Pop <tomas.pop@sensirion.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Use ATTRIBUTE_GROUPS macro and devm_hwmon_device_register_with_groups to
simplify the code a bit.
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Tested-by: Per Dalén <per.dalen@appeartv.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Generic detection leads to too many false positives, so drop it. FWIW
sensors-detect does not have such generic detection. If the user wants
to force the driver to bind to a not yet supported chip, he/she can
still do so using sysfs attribute new_device.
Signed-off-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
All devices supported by ina2xx are bidirectional and report the
measured shunt voltage and power values as a signed 16 bit, but the
current driver implementation caches all registers as u16, leading
to an incorrect sign extension when reporting to userspace in
ina2xx_get_value().
This patch fixes the problem by casting the signed registers to s16.
Tested on an INA219.
Signed-off-by: Fabio Baltieri <fabio.baltieri@gmail.com>
Cc: stable@vger.kernel.org # 3.10+
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
The connection struct with nodeid 0 is the listening socket,
not a connection to another node. The sctp resend function
was not checking that the nodeid was valid (non-zero), so it
would mistakenly get and resend on the listening connection
when nodeid was zero.
Signed-off-by: Lidong Zhong <lzhong@suse.com>
Signed-off-by: David Teigland <teigland@redhat.com>
Fix this dependency on the locking tree's smp_mb*() API changes:
kernel/sched/idle.c:247:3: error: implicit declaration of function ‘smp_mb__after_atomic’ [-Werror=implicit-function-declaration]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
* pm-cpufreq:
cpufreq: cpufreq-cpu0: remove dependency on THERMAL and REGULATOR
cpufreq: tegra: update comment for clarity
cpufreq: intel_pstate: Remove duplicate CPU ID check
cpufreq: Mark CPU0 driver with CPUFREQ_NEED_INITIAL_FREQ_CHECK flag
cpufreq: governor: remove copy_prev_load from 'struct cpu_dbs_common_info'
cpufreq: governor: Be friendly towards latency-sensitive bursty workloads
cpufreq: ppc-corenet-cpu-freq: do_div use quotient
Revert "cpufreq: Enable big.LITTLE cpufreq driver on arm64"
cpufreq: Tegra: implement intermediate frequency callbacks
cpufreq: add support for intermediate (stable) frequencies
* acpi-general:
ACPI: Fix bug when ACPI reset register is implemented in system memory
* acpi-video:
ACPI / video: Change the default for video.use_native_backlight to 1
do_posix_clock_monotonic_gettime() is a leftover from the initial
posix timer implementation which maps to ktime_get_ts() and returns
the monotonic time in a timespec.
Use ktime based ktime_get() and use the ktime_delta_us() function to
calculate the delta instead of open coding the timespec math.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
do_posix_clock_monotonic_gettime() is a leftover from the initial
posix timer implementation which maps to ktime_get_ts().
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This patch will verify the pin's coverter selection for an active stream
when an unsol event reports this pin becomes available again after a display
mode change or hot-plug event.
For Haswell+ and Valleyview: display mode change or hot-plug can change the
transcoder:port connection and make all the involved audio pins share the 1st
converter. So the stream using 1st convertor will flow to multiple pins
but active streams using other converters will fail. This workaround
is to assure the pin selects the right conveter and an assigned converter is
not shared by other unused pins.
Signed-off-by: Mengdong Lin <mengdong.lin@intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Cancel the optimization of compiler for struct snd_compr_avail
which size will be 0x1c in 32bit kernel while 0x20 in 64bit
kernel under the optimizer. That will make compaction between
32bit and 64bit. So add packed to fix the size of struct
snd_compr_avail to 0x1c for all platform.
Signed-off-by: Zhang Dongxing <dongxing.zhang@intel.com>
Signed-off-by: xiaoming wang <xiaoming.wang@intel.com>
Acked-by: Vinod Koul <vinod.koul@intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
These defconfigs contain the CONFIG_M25P80 symbol, which is now
dependent on the MTD_SPI_NOR symbol. Add CONFIG_MTD_SPI_NOR to the
relevant defconfigs.
At the same time, drop the now-nonexistent CONFIG_MTD_CHAR symbol.
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Cc: Steven Miao <realmz6@gmail.com>
Cc: adi-buildroot-devel@lists.sourceforge.net
Cc: linux-kernel@vger.kernel.org
We have a number of front-end drivers for SDHCI_PLTFM, some of them
use 'select MMC_SDHCI_PLTFM', others use 'depends on'. This is
inconsistent and confusing, and in one case has also led to a
build error because of incomplete dependencies:
warning: (MMC_SDHCI_PXAV3 && MMC_SDHCI_PXAV2 && MMC_SDHCI_BCM_KONA) selects MMC_SDHCI_PLTFM which has unmet direct dependencies (MMC && MMC_SDHCI)
drivers/built-in.o: In function `sdhci_sirf_resume':
:(.text+0xaaacb4): undefined reference to `sdhci_resume_host'
drivers/built-in.o: In function `sdhci_sirf_suspend':
:(.text+0xaaacf8): undefined reference to `sdhci_suspend_host'
drivers/built-in.o: In function `sdhci_sirf_probe':
:(.text+0xaaaf44): undefined reference to `sdhci_add_host'
:(.text+0xaaaf50): undefined reference to `sdhci_remove_host'
This changes Kconfig to use 'depends on MMC_SDHCI_PLTFM' for all these
cases, to fix the build error and make the logic more logical.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
The MMC host driver should not select the pmic driver, since that
may have other dependencies, notably i2c in this case. It's not
clear what the exact requirement of the driver is, but to preserve
the behavior, this patch changes the 'select' into 'depends on',
meaning you now have to turn on TPS65010 explicitly and then
MMC_OMAP.
Found during randconfig build testing.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: linux-omap@vger.kernel.org
Cc: Jarkko Nikula <jarkko.nikula@bitmer.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
gcc correctly points out that hw_state can be used uninitially
in the mvsd_setup_data() function. This rearranges the function
to ensure it always contains a proper value.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Nicolas Pitre <nico@fluxnic.net>
Cc: Chris Ball <chris@printf.net>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: linux-mmc@vger.kernel.org
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
This avoids a build error due to the use of flush_dcache_page.
drivers/mmc/host/atmel-mci.c: In function 'atmci_read_data_pio':
drivers/mmc/host/atmel-mci.c:1870:5: error: implicit declaration of function 'flush_dcache_page' [-Werror=implicit-function-declaration]
flush_dcache_page(sg_page(sg));
^
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Ludovic Desroches <ludovic.desroches@atmel.com>
Acked-by: Ludovic Desroches <ludovic.desroches@atmel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
The sdhci core was refactored recently and some of those
refactorings required changes in every sdhci platform driver.
Those updates happened around the same time as when the msm
driver was merged so the refactorings missed the msm driver.
Hook in the basic library functions so that we can boot apq8074
dragonboards again instead of crashing when we try to jump to
NULL function pointers.
Reported-by: Kevin Hilman <khilman@linaro.org>
Cc: Georgi Djakov <gdjakov@mm-sol.com>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Acked-by: Kumar Gala <galak@codeaurora.org>
Reviewed-by: Georgi Djakov <gdjakov@mm-sol.com>
Tested-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Fix a number of wrong print formats.
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski+renesas@gmail.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
The rule to create the final images uses a zImage.% pattern.
Unfortunately, this also matches the names of the zImage.*.lds linker
scripts, which appear as a dependency of the final images. This somehow
worked when $(srctree) used to be an absolute path, but now the pattern
matches too much. List only the images from $(image-y) as the target of
the rule, to avoid the circular dependency.
Reported-and-tested-by: Mike Qiu <qiudayu@linux.vnet.ibm.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>
Commit dd34c37aa3 (gpio: of: Allow -gpio suffix for property names)
added parsing for both -gpio and -gpios suffix but also changed
the handling for deferred probe unintentionally. Because of the
looping the second name will now return -ENOENT instead of
-EPROBE_DEFER. Fix the issue by breaking out of the loop if
-EPROBE_DEFER is encountered.
Signed-off-by: Tony Lindgren <tony@atomide.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Dentry that had been through (or into) __dentry_kill() might be seen
by shrink_dentry_list(); that's normal, it'll be taken off the shrink
list and freed if __dentry_kill() has already finished. The problem
is, its ->d_parent might be pointing to already freed dentry, so
lock_parent() needs to be careful.
We need to check that dentry hasn't already gone into __dentry_kill()
*and* grab rcu_read_lock() before dropping ->d_lock - the latter makes
sure that whatever we see in ->d_parent after dropping ->d_lock it
won't be freed until we drop rcu_read_lock().
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Per Hurtig