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2014-03-24powerpc/book3s: Fix CFAR clobbering issue in machine check handler.Mahesh Salgaonkar
While checking powersaving mode in machine check handler at 0x200, we clobber CFAR register. Fix it by saving and restoring it during beq/bgt. Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2014-03-24powerpc/compat: 32-bit little endian machine name is ppcle, not ppcAnton Blanchard
I noticed this when testing setarch. No, we don't magically support a big endian userspace on a little endian kernel. Signed-off-by: Anton Blanchard <anton@samba.org> Cc: stable@vger.kernel.org # v3.10+ Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2014-03-24powerpc/le: Big endian arguments for ppc_rtas()Greg Kurz
The ppc_rtas() syscall allows userspace to interact directly with RTAS. For the moment, it assumes every thing is big endian and returns either EINVAL or EFAULT when called in a little endian environment. As suggested by Benjamin, to avoid bugs when userspace wants to pass a non 32 bit value to RTAS, it is far better to stick with a simple rationale: ppc_rtas() should be called with a big endian rtas_args structure. With this patch, it is now up to userspace to forge big endian arguments, as expected by RTAS. Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2014-03-24powerpc: Use default set of netfilter modules (CONFIG_NETFILTER_ADVANCED=n)Anton Blanchard
Our netfilter options are stale and important things like masquerading are no longer enabled. Instead of trying to keep up with any updates, set CONFIG_NETFILTER_ADVANCED=n on ppc64* and pseries* defconfigs. This enables the most common netfilter modules for us. While here, enable the network bridge module which is heavily used in KVM setups. Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2014-03-24powerpc/defconfigs: Enable THP in pseries defconfigAneesh Kumar K.V
We also set it to be enabled always. This helps in wider testing Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2014-03-24powerpc/mm: Make sure a local_irq_disable prevent a parallel THP splitAneesh Kumar K.V
We have generic code like the one in get_futex_key that assume that a local_irq_disable prevents a parallel THP split. Support that by adding a dummy smp call function after setting _PAGE_SPLITTING. Code paths like get_user_pages_fast still need to check for _PAGE_SPLITTING after disabling IRQ which indicate that a parallel THP splitting is ongoing. Now if they don't find _PAGE_SPLITTING set, then we can be sure that parallel split will now block in pmdp_splitting flush until we enables IRQ Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2014-03-24powerpc: Rate-limit users spamming kernel log bufferMichael Neuling
The facility unavailable exception can be triggered from userspace by accessing PMU registers when EBB is not enabled. This causes the included pr_err() to run, hence spamming the kernel log buffer. This avoids this by rate limiting these messages. Signed-off-by: Michael Neuling <mikey@neuling.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2014-03-24powerpc/perf: Fix handling of L3 events with bank == 1Michael Ellerman
Currently we reject events which have the L3 bank == 1, such as 0x000084918F, because the cache field is non-zero. However that is incorrect, because although the bank is non-zero, the value we would write into MMCRC is zero, and so we can count the event. So fix the check to ignore the bank selector when checking whether the cache selector is non-zero. Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2014-03-24powerpc/perf/hv_{gpci, 24x7}: Add documentation of device attributesCody P Schafer
gpci and 24x7 expose some device specific attributes. Add some documentation for them. Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2014-03-24powerpc/perf: Add kconfig option for hypervisor provided countersCody P Schafer
The commit adds a Kconfig option which allows the hv_gpci and hv_24x7 PMUs, added in the preceeding commits, to be built. Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2014-03-24powerpc/perf: Add support for the hv 24x7 interfaceCody P Schafer
This provides a basic interface between hv_24x7 and perf. Similar to the one provided for gpci, it lacks transaction support and does not list any events. Example usage via perf tool: perf stat -e 'hv_24x7/domain=2,offset=8,starting_index=0,lpar=0xffffffff/' -r 0 -C 0 -x ' ' sleep 0.1 Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2014-03-24powerpc/perf: Add support for the hv gpci (get performance counter info) ↵Cody P Schafer
interface This provides a basic link between perf and hv_gpci. Notably, it does not yet support transactions and does not list any events (they can still be manually composed). Example usage via perf tool: perf stat -e 'hv_gpci/counter_info_version=3,offset=0,length=8,secondary_index=0,starting_index=0xffffffff,request=0x10/' -r 0 -C 0 -x ' ' sleep 0.1 Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2014-03-24powerpc/perf: Add macros for defining event fields & formatsCody P Schafer
Add two macros which generate functions to extract the relevent bits from event->attr.config{,1,2}. EVENT_DEFINE_RANGE() defines an accessor for a range of bits in the event, as well as a "max" function that gives the maximum value of the field based on the bit width. EVENT_DEFINE_RANGE_FORMAT() defines the accessor & max routine and also a format attribute for use in the PMU's attr_groups. Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com> [mpe: move to powerpc, ugly but descriptive macro names] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2014-03-24powerpc/perf: Add a shared interface to get gpci version and capabilitiesCody P Schafer
This exposes a simple way to grab the firmware provided collect_priveliged, ga, expanded, and lab capability bits. All of these bits come in from the same gpci request, so we've exposed all of them. Only the collect_priveliged bit is really used by the hv-gpci/hv-24x7 code, the other bits are simply exposed in sysfs to inform the user. Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2014-03-24powerpc/perf: Add 24x7 interface headersCody P Schafer
24x7 (also called hv_24x7 or H_24X7) is an interface to obtain performance counters from the hypervisor. These counters do not have a fixed format/possition and are instead documented in a "24x7 Catalog", which is provided by the hypervisor (that interface is also documented paritialy in the included hv-24x7-catalog.h and fully in at https://raw.githubusercontent.com/jmesmon/catalog-24x7/master/hv-24x7-catalog.h ). The 24x7 data access is simply a copy operation into a 4 dimentional array of 64bit counters (from hypervisor to kernel memory). There is no interupt triggered on overflow, these are completely disjoint from the typical power pmu. This method of obtaining performance counters from the hypervisor is intended to paritialy replace the gpci interface. Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2014-03-24powerpc/perf: Add hv_gpci interface headerCody P Schafer
"H_GetPerformanceCounterInfo" (refered to as hv_gpci or just gpci from here on) is an interface to retrieve specific performance counters and other data from the hypervisor. All outputs have a fixed format. This header only describes the portions of the interface that we plan on using in linux at this time. Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2014-03-24powerpc: Add hvcalls for 24x7 and gpci (Get Performance Counter Info)Cody P Schafer
Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2014-03-24sysfs: create bin_attributes under the requested groupCody P Schafer
bin_attributes created/updated in create_files() (such as those listed via (struct device).attribute_groups) were not placed under the specified group, and instead appeared in the base kobj directory. Fix this by making bin_attributes use creating code similar to normal attributes. A quick grep shows that no one is using bin_attrs in a named attribute group yet, so we can do this without breaking anything in usespace. Note that I do not add is_visible() support to bin_attributes, though that could be done as well. This is a copy of the patch already merged in Greg's tree. Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2014-03-24powerpc/perf: Enable BHRB access for EBB eventsMichael Ellerman
The previous commit added constraint and register handling to allow processes using EBB (Event Based Branches) to request access to the BHRB (Branch History Rolling Buffer). With that in place we can allow processes using EBB to access the BHRB. This is achieved by setting BHRBA in MMCR0 when we enable EBB access. We must also clear BHRBA when we are disabling. Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2014-03-24powerpc/perf: Add BHRB constraint and IFM MMCRA handling for EBBMichael Ellerman
We want a way for users of EBB (Event Based Branches) to also access the BHRB (Branch History Rolling Buffer). EBB does not interoperate with our existing BHRB support, which is wired into the generic Linux branch stack sampling support. To support EBB & BHRB we add three new bits to the event code. The first bit indicates that the event wants access to the BHRB, and the other two bits indicate the desired IFM (Instruction Filtering Mode). We allow multiple events to request access to the BHRB, but they must agree on the IFM value. Events which are not interested in the BHRB can also interoperate with events which do. Finally we program the desired IFM value into MMCRA. Although we do this for every event, we know that the value will be identical for all events that request BHRB access. Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2014-03-24powerpc/perf: Avoid mutating event in power8_get_constraint()Michael Ellerman
We only need to mask the EBB bit out of the event for the check of the special PMC 5 & 6 events. So use a local to do it just for that code, rather than changing the event value for the life of the function. While we're there move the set of mask and value after all the checks. Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2014-03-24powerpc/perf: Clean up the EBB hash defines a littleMichael Ellerman
Rather than using PERF_EVENT_CONFIG_EBB_SHIFT everywhere, add an EVENT_EBB_SHIFT like every other event and use that. Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2014-03-24powerpc/perf: Reject EBB events which specify a sample_typeMichael Ellerman
Although we already block EBB events which request sampling using sample_period, technically it's possible for an event to set sample_type but not sample_period. Nothing terrible will happen if an EBB event does specify sample_type, but it signals a major confusion on the part of userspace, and so we do them the favor of rejecting it. Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2014-03-24powerpc/perf: Add lost exception workaroundMichael Ellerman
Some power8 revisions have a hardware bug where we can lose a PMU exception, this commit adds a workaround to detect the bad condition and rectify the situation. See the comment in the commit for a full description. Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2014-03-24powerpc: Add a cpu feature CPU_FTR_PMAO_BUGMichael Ellerman
Some power8 revisions have a hardware bug where we can lose a Performance Monitor (PMU) exception under certain circumstances. We will be adding a workaround for this case, see the next commit for details. The observed behaviour is that writing PMAO doesn't cause an exception as we would expect, hence the name of the feature. Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2014-03-24powerpc/perf: Define perf_event_print_debug() to print PMU register valuesAnshuman Khandual
Currently the sysrq ShowRegs command does not print any PMU registers as we have an empty definition for perf_event_print_debug(). This patch defines perf_event_print_debug() to print various PMU registers. Example output: CPU: 0 PMU registers, ppmu = POWER7 n_counters = 6 PMC1: 00000000 PMC2: 00000000 PMC3: 00000000 PMC4: 00000000 PMC5: 00000000 PMC6: 00000000 PMC7: deadbeef PMC8: deadbeef MMCR0: 0000000080000000 MMCR1: 0000000000000000 MMCRA: 0f00000001000000 SIAR: 0000000000000000 SDAR: 0000000000000000 SIER: 0000000000000000 Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com> [mpe: Fix 32 bit build and rework formatting for compactness] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2014-03-24powerpc/perf: Make some new raw event codes available in sysfsAnshuman Khandual
This patchset adds some missing event list for POWER7 PMU raw events which are exported through sysfs interface. Also updates the ABI documentation to add all the sysfs exported raw events. Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2014-03-24powerpc: Update ppc4xx maintainerJosh Boyer
Alistair Popple has volunteered to take over maintainership of the ppc4xx stuff upstream. Switch the MAINTAINERS entry over to him. Signed-off-by: Josh Boyer <jwboyer@gmail.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2014-03-24powerpc/powernv: hwmon driver for power values, fan rpm and temperatureShivaprasad G Bhat
This patch adds basic kernel enablement for reading power values, fan speed rpm and temperature values on powernv platforms which will be exported to user space through sysfs interface. Signed-off-by: Shivaprasad G Bhat <sbhat@linux.vnet.ibm.com> Signed-off-by: Neelesh Gupta <neelegup@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2014-03-24powerpc/powernv: Enable fetching of platform sensor dataNeelesh Gupta
This patch enables fetching of various platform sensor data through OPAL and expects a sensor handle from the driver to pass to OPAL. Signed-off-by: Neelesh Gupta <neelegup@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2014-03-24powerpc/powernv: Enable reading and updating of system parametersNeelesh Gupta
This patch enables reading and updating of system parameters through OPAL call. Signed-off-by: Neelesh Gupta <neelegup@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2014-03-24powerpc/powernv: Infrastructure to support OPAL async completionNeelesh Gupta
This patch adds support for notifying the clients of their request completion. Clients request for the token before making OPAL call and then wait for the response. This patch uses messaging infrastructure to pull the data to linux by registering itself for the message type OPAL_MSG_ASYNC_COMP. Signed-off-by: Neelesh Gupta <neelegup@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2014-03-23parisc: locks: remove redundant arch_*_relax operationsWill Deacon
Now that the arch_{spin,read,write}_relax macros default to cpu_relax(), remove the redundant definitions for parisc. Cc: Helge Deller <deller@gmx.de> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Helge Deller <deller@gmx.de>
2014-03-23parisc: wire up sys_utimesHelge Deller
We seem to be nearly the only platform which does not provide the sys_utimes syscall. Adding it now makes our life much easier with userspace applications (like dietlibc and e2fsprogs) since we then behave like all other platforms too and don't need extra patches which are hard to get upstream anyway because we are not a mainstream architecture. Signed-off-by: Helge Deller <deller@gmx.de> Cc: stable@vger.kernel.org # v3.13
2014-03-23parisc: Remove unused CONFIG_PARISC_TMPALIAS codeJohn David Anglin
The attached change removes the unused and experimental CONFIG_PARISC_TMPALIAS code. It doesn't work and I don't believe it will ever be used. Signed-off-by: John David Anglin <dave.anglin@bell.net> Signed-off-by: Helge Deller <deller@gmx.de>
2014-03-23partly revert commit 8a10bc9: parisc/sti_console: prefer Linux fonts over ↵Helge Deller
built-in ROM fonts STI console is used on parisc and m68k HP machines. This patch partly reverts my previous commit and as such restores the fonts for the m68k machines. Signed-off-by: Helge Deller <deller@gmx.de> Cc: stable@vger.kernel.org # v3.13
2014-03-23Merge remote-tracking branches 'asoc/topic/simple' and 'asoc/topic/sirf' ↵Mark Brown
into asoc-next
2014-03-23Merge remote-tracking branch 'asoc/topic/rcar' into asoc-nextMark Brown
2014-03-23Merge remote-tracking branches 'asoc/topic/max98090' and 'asoc/topic/omap' ↵Mark Brown
into asoc-next
2014-03-23Merge remote-tracking branches 'asoc/topic/intel', 'asoc/topic/io' and ↵Mark Brown
'asoc/topic/kirkwood' into asoc-next
2014-03-23Merge remote-tracking branch 'asoc/topic/davinci' into asoc-nextMark Brown
2014-03-23Merge remote-tracking branch 'asoc/topic/cs42xx8' into asoc-nextMark Brown
2014-03-23Merge remote-tracking branch 'asoc/topic/codecs' into asoc-nextMark Brown
2014-03-23Merge remote-tracking branch 'asoc/topic/core' into asoc-nextMark Brown
2014-03-23Merge tag 'asoc-v3.15-2' into asoc-nextMark Brown
ASoC: Updates for v3.15 This is mostly a few additional fixes from Lars-Peter, a new driver and cleaning up a git failure with merging the Intel branch (combined with an xargs failure to pay attention to error codes). The history lists a bunch of additional commits for the branch but the content of those commits is actually present already but not recorded in history due to git failing. Unfortunately xargs is used in the merge script and it doesn't do a good job of noticing errors from the commands it invokes. # gpg: Signature made Thu 13 Mar 2014 14:25:44 GMT using RSA key ID 7EA229BD # gpg: Good signature from "Mark Brown <broonie@sirena.org.uk>" # gpg: aka "Mark Brown <broonie@debian.org>" # gpg: aka "Mark Brown <broonie@kernel.org>" # gpg: aka "Mark Brown <broonie@tardis.ed.ac.uk>" # gpg: aka "Mark Brown <broonie@linaro.org>" # gpg: aka "Mark Brown <Mark.Brown@linaro.org>"
2014-03-23Merge tag 'asoc-v3.15' into asoc-nextMark Brown
ASoC: Updates for v3.15 Quite a busy release for ASoC this time, more on janitorial work than exciting new features but welcome nontheless: - Lots of cleanups from Takashi for enumerations; the original API for these was error prone so he's refactored lots of code to use more modern APIs which avoid issues. - Elimination of the ASoC level wrappers for I2C and SPI moving us closer to converting to regmap completely and avoiding some randconfig hassle. - Provide both manually and transparently locked DAPM APIs rather than a mix of the two fixing some concurrency issues. - Start converting CODEC drivers to use separate bus interface drivers rather than having them all in one file helping avoid dependency issues. - DPCM support for Intel Haswell and Bay Trail platforms. - Lots of work on improvements for simple-card, DaVinci and the Renesas rcar drivers. - New drivers for Analog Devices ADAU1977, TI PCM512x and parts of the CSR SiRF SoC. # gpg: Signature made Wed 12 Mar 2014 23:05:45 GMT using RSA key ID 7EA229BD # gpg: Good signature from "Mark Brown <broonie@sirena.org.uk>" # gpg: aka "Mark Brown <broonie@debian.org>" # gpg: aka "Mark Brown <broonie@kernel.org>" # gpg: aka "Mark Brown <broonie@tardis.ed.ac.uk>" # gpg: aka "Mark Brown <broonie@linaro.org>" # gpg: aka "Mark Brown <Mark.Brown@linaro.org>"
2014-03-23Merge remote-tracking branches 'asoc/fix/cs42l51', 'asoc/fix/cs42l52', ↵Mark Brown
'asoc/fix/cs42l73', 'asoc/fix/rcar', 'asoc/fix/spear' and 'asoc/fix/tegra' into asoc-linus
2014-03-23ASoC: pcm: Drop incorrect double/extra freesMark Brown
The changes in "ASoC: pcm: free path list before exiting from error conditions" actually introduced both double frees (in case where the path list was allocated but empty) and frees of unallocated memory (in cases where the error being handled was -ENOMEM. Drop the commit for now. Fixes: e4ad1accb (ASoC: pcm: free path list before exiting from error conditions) Reported-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Mark Brown <broonie@linaro.org> Cc: stable@vger.kernel.org
2014-03-23rcuwalk: recheck mount_lock after mountpoint crossing attemptsAl Viro
We can get false negative from __lookup_mnt() if an unrelated vfsmount gets moved. In that case legitimize_mnt() is guaranteed to fail, and we will fall back to non-RCU walk... unless we end up running into a hard error on a filesystem object we wouldn't have reached if not for that false negative. IOW, delaying that check until the end of pathname resolution is wrong - we should recheck right after we attempt to cross the mountpoint. We don't need to recheck unless we see d_mountpoint() being true - in that case even if we have just raced with mount/umount, we can simply go on as if we'd come at the moment when the sucker wasn't a mountpoint; if we run into a hard error as the result, it was a legitimate outcome. __lookup_mnt() returning NULL is different in that respect, since it might've happened due to operation on completely unrelated mountpoint. Cc: stable@vger.kernel.org Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-03-23make prepend_name() work correctly when called with negative *buflenAl Viro
In all callchains leading to prepend_name(), the value left in *buflen is eventually discarded unused if prepend_name() has returned a negative. So we are free to do what prepend() does, and subtract from *buflen *before* checking for underflow (which turns into checking the sign of subtraction result, of course). Cc: stable@vger.kernel.org Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>