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2012-09-23rcu: Add PROVE_RCU_DELAY to provoke difficult racesPaul E. McKenney
There have been some recent bugs that were triggered only when preemptible RCU's __rcu_read_unlock() was preempted just after setting ->rcu_read_lock_nesting to INT_MIN, which is a low-probability event. Therefore, reproducing those bugs (to say nothing of gaining confidence in alleged fixes) was quite difficult. This commit therefore creates a new debug-only RCU kernel config option that forces a short delay in __rcu_read_unlock() to increase the probability of those sorts of bugs occurring. Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2012-08-01Merge branch 'for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull second vfs pile from Al Viro: "The stuff in there: fsfreeze deadlock fixes by Jan (essentially, the deadlock reproduced by xfstests 068), symlink and hardlink restriction patches, plus assorted cleanups and fixes. Note that another fsfreeze deadlock (emergency thaw one) is *not* dealt with - the series by Fernando conflicts a lot with Jan's, breaks userland ABI (FIFREEZE semantics gets changed) and trades the deadlock for massive vfsmount leak; this is going to be handled next cycle. There probably will be another pull request, but that stuff won't be in it." Fix up trivial conflicts due to unrelated changes next to each other in drivers/{staging/gdm72xx/usb_boot.c, usb/gadget/storage_common.c} * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (54 commits) delousing target_core_file a bit Documentation: Correct s_umount state for freeze_fs/unfreeze_fs fs: Remove old freezing mechanism ext2: Implement freezing btrfs: Convert to new freezing mechanism nilfs2: Convert to new freezing mechanism ntfs: Convert to new freezing mechanism fuse: Convert to new freezing mechanism gfs2: Convert to new freezing mechanism ocfs2: Convert to new freezing mechanism xfs: Convert to new freezing code ext4: Convert to new freezing mechanism fs: Protect write paths by sb_start_write - sb_end_write fs: Skip atime update on frozen filesystem fs: Add freezing handling to mnt_want_write() / mnt_drop_write() fs: Improve filesystem freezing handling switch the protection of percpu_counter list to spinlock nfsd: Push mnt_want_write() outside of i_mutex btrfs: Push mnt_want_write() outside of i_mutex fat: Push mnt_want_write() outside of i_mutex ...
2012-07-31switch the protection of percpu_counter list to spinlockAl Viro
... making percpu_counter_destroy() non-blocking Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-07-30Merge tag 'writeback-proportions' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux Pull writeback updates from Wu Fengguang: "Use time based periods to age the writeback proportions, which can adapt equally well to fast/slow devices." Fix up trivial conflict in comment in fs/sync.c * tag 'writeback-proportions' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux: writeback: Fix some comment errors block: Convert BDI proportion calculations to flexible proportions lib: Fix possible deadlock in flexible proportion code lib: Proportions with flexible period
2012-07-30Merge branch 'akpm' (Andrew's patch-bomb)Linus Torvalds
Merge Andrew's first set of patches: "Non-MM patches: - lots of misc bits - tree-wide have_clk() cleanups - quite a lot of printk tweaks. I draw your attention to "printk: convert the format for KERN_<LEVEL> to a 2 byte pattern" which looks a bit scary. But afaict it's solid. - backlight updates - lib/ feature work (notably the addition and use of memweight()) - checkpatch updates - rtc updates - nilfs updates - fatfs updates (partial, still waiting for acks) - kdump, proc, fork, IPC, sysctl, taskstats, pps, etc - new fault-injection feature work" * Merge emailed patches from Andrew Morton <akpm@linux-foundation.org>: (128 commits) drivers/misc/lkdtm.c: fix missing allocation failure check lib/scatterlist: do not re-write gfp_flags in __sg_alloc_table() fault-injection: add tool to run command with failslab or fail_page_alloc fault-injection: add selftests for cpu and memory hotplug powerpc: pSeries reconfig notifier error injection module memory: memory notifier error injection module PM: PM notifier error injection module cpu: rewrite cpu-notifier-error-inject module fault-injection: notifier error injection c/r: fcntl: add F_GETOWNER_UIDS option resource: make sure requested range is included in the root range include/linux/aio.h: cpp->C conversions fs: cachefiles: add support for large files in filesystem caching pps: return PTR_ERR on error in device_create taskstats: check nla_reserve() return sysctl: suppress kmemleak messages ipc: use Kconfig options for __ARCH_WANT_[COMPAT_]IPC_PARSE_VERSION ipc: compat: use signed size_t types for msgsnd and msgrcv ipc: allow compat IPC version field parsing if !ARCH_WANT_OLD_COMPAT_IPC ipc: add COMPAT_SHMLBA support ...
2012-07-30lib/scatterlist: do not re-write gfp_flags in __sg_alloc_table()Mandeep Singh Baines
We are seeing a lot of sg_alloc_table allocation failures using the new drm prime infrastructure. We isolated the cause to code in __sg_alloc_table that was re-writing the gfp_flags. There is a comment in the code that suggest that there is an assumption about the allocation coming from a memory pool. This was likely true when sg lists were primarily used for disk I/O. Signed-off-by: Mandeep Singh Baines <msb@chromium.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Cong Wang <amwang@redhat.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Rob Clark <rob.clark@linaro.org> Cc: Sumit Semwal <sumit.semwal@linaro.org> Cc: Inki Dae <inki.dae@samsung.com> Cc: Dave Airlie <airlied@redhat.com> Cc: Sonny Rao <sonnyrao@chromium.org> Cc: Olof Johansson <olofj@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-30powerpc: pSeries reconfig notifier error injection moduleAkinobu Mita
This provides the ability to inject artifical errors to pSeries reconfig notifier chain callbacks. It is controlled through debugfs interface under /sys/kernel/debug/notifier-error-inject/pSeries-reconfig If the notifier call chain should be failed with some events notified, write the error code to "actions/<notifier event>/error". Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: Pavel Machek <pavel@ucw.cz> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Greg KH <greg@kroah.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <michael@ellerman.id.au> Cc: Dave Jones <davej@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-30memory: memory notifier error injection moduleAkinobu Mita
This provides the ability to inject artifical errors to memory hotplug notifier chain callbacks. It is controlled through debugfs interface under /sys/kernel/debug/notifier-error-inject/memory If the notifier call chain should be failed with some events notified, write the error code to "actions/<notifier event>/error". Example: Inject memory hotplug offline error (-12 == -ENOMEM) # cd /sys/kernel/debug/notifier-error-inject/memory # echo -12 > actions/MEM_GOING_OFFLINE/error # echo offline > /sys/devices/system/memory/memoryXXX/state bash: echo: write error: Cannot allocate memory Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: Pavel Machek <pavel@ucw.cz> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Greg KH <greg@kroah.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <michael@ellerman.id.au> Cc: Dave Jones <davej@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-30PM: PM notifier error injection moduleAkinobu Mita
This provides the ability to inject artifical errors to PM notifier chain callbacks. It is controlled through debugfs interface under /sys/kernel/debug/notifier-error-inject/pm Each of the files in "error" directory represents an event which can be failed and contains the error code. If the notifier call chain should be failed with some events notified, write the error code to the files. If the notifier call chain should be failed with some events notified, write the error code to "actions/<notifier event>/error". Example: Inject PM suspend error (-12 = -ENOMEM) # cd /sys/kernel/debug/notifier-error-inject/pm # echo -12 > actions/PM_SUSPEND_PREPARE/error # echo mem > /sys/power/state bash: echo: write error: Cannot allocate memory Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Acked-by: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Pavel Machek <pavel@ucw.cz> Cc: Greg KH <greg@kroah.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <michael@ellerman.id.au> Cc: Dave Jones <davej@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-30cpu: rewrite cpu-notifier-error-inject moduleAkinobu Mita
Rewrite existing cpu-notifier-error-inject module to use debugfs based new framework. This change removes cpu_up_prepare_error and cpu_down_prepare_error module parameters which were used to specify error code to be injected. We could keep these module parameters for backward compatibility by module_param_cb but it seems overkill for this module. This provides the ability to inject artifical errors to CPU notifier chain callbacks. It is controlled through debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu If the notifier call chain should be failed with some events notified, write the error code to "actions/<notifier event>/error". Example1: inject CPU offline error (-1 == -EPERM) # cd /sys/kernel/debug/notifier-error-inject/cpu # echo -1 > actions/CPU_DOWN_PREPARE/error # echo 0 > /sys/devices/system/cpu/cpu1/online bash: echo: write error: Operation not permitted Example2: inject CPU online error (-2 == -ENOENT) # cd /sys/kernel/debug/notifier-error-inject/cpu # echo -2 > actions/CPU_UP_PREPARE/error # echo 1 > /sys/devices/system/cpu/cpu1/online bash: echo: write error: No such file or directory Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: Pavel Machek <pavel@ucw.cz> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Greg KH <greg@kroah.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <michael@ellerman.id.au> Cc: Dave Jones <davej@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-30fault-injection: notifier error injectionAkinobu Mita
This patchset provides kernel modules that can be used to test the error handling of notifier call chain failures by injecting artifical errors to the following notifier chain callbacks. * CPU notifier * PM notifier * memory hotplug notifier * powerpc pSeries reconfig notifier Example: Inject CPU offline error (-1 == -EPERM) # cd /sys/kernel/debug/notifier-error-inject/cpu # echo -1 > actions/CPU_DOWN_PREPARE/error # echo 0 > /sys/devices/system/cpu/cpu1/online bash: echo: write error: Operation not permitted The patchset also adds cpu and memory hotplug tests to tools/testing/selftests These tests first do simple online and offline test and then do fault injection tests if notifier error injection module is available. This patch: The notifier error injection provides the ability to inject artifical errors to specified notifier chain callbacks. It is useful to test the error handling of notifier call chain failures. This adds common basic functions to define which type of events can be fail and to initialize the debugfs interface to control what error code should be returned and which event should be failed. Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: Pavel Machek <pavel@ucw.cz> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Greg KH <greg@kroah.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <michael@ellerman.id.au> Cc: Dave Jones <davej@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-30lib/crc32.c: fix unused variables warningsThiago Rafael Becker
Variables t4, t5, t6 and t7 are only used when CRC_LE_BITS != 32. Fix the following compilation warnings: lib/crc32.c: In function 'crc32_body': lib/crc32.c:77:55: warning: unused variable 't7' lib/crc32.c:77:41: warning: unused variable 't6' lib/crc32.c:77:27: warning: unused variable 't5' lib/crc32.c:77:13: warning: unused variable 't4' Signed-off-by: Thiago Rafael Becker <trbecker@trbecker.org> Cc: "Darrick J. Wong" <djwong@us.ibm.com> Cc: Bob Pearson <rpearson@systemfabricworks.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-30spinlock_debug: print offset in addition to symbol nameStephen Boyd
If there are two spinlocks embedded in a structure that kallsyms knows about and one of the spinlocks locks up we will print the name of the containing structure instead of the address of the lock. This is quite bad, so let's use %pS instead of %ps so we get an offset in addition to the symbol so we can determine which particular lock is having problems. Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-30atomic64_test: simplify the #ifdef for atomic64_dec_if_positive() testCatalin Marinas
Introduce CONFIG_ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE and use this instead of the multitude of #if defined() checks in atomic64_test.c Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Russell King <linux@arm.linux.org.uk> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-30string: introduce memweight()Akinobu Mita
memweight() is the function that counts the total number of bits set in memory area. Unlike bitmap_weight(), memweight() takes pointer and size in bytes to specify a memory area which does not need to be aligned to long-word boundary. [akpm@linux-foundation.org: rename `w' to `ret'] Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: Anders Larsen <al@alarsen.net> Cc: Alasdair Kergon <agk@redhat.com> Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Cc: Mark Fasheh <mfasheh@suse.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Jan Kara <jack@suse.cz> Cc: Andreas Dilger <adilger.kernel@dilger.ca> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Matthew Wilcox <matthew@wil.cx> Cc: Mauro Carvalho Chehab <mchehab@infradead.org> Cc: Tony Luck <tony.luck@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-30vsprintf: add support of '%*ph[CDN]'Andy Shevchenko
There are many places in the kernel where the drivers print small buffers as a hex string. This patch adds a support of the variable width buffer to print it as a hex string with a delimiter. The idea came from Pavel Roskin here: http://www.digipedia.pl/usenet/thread/18835/17449/ Sample output of pr_info("buf[%d:%d] %*phC\n", from, len, len, &buf[from]); could be look like this: [ 0.726130] buf[51:8] e8:16:b6:ef:e3:74:45:6e [ 0.750736] buf[59:15] 31:81:b8:3f:35:49:06:ae:df:32:06:05:4a:af:55 [ 0.757602] buf[17:5] ac:16:d5:2c:ef Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Joe Perches <joe@perches.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-30lib/vsprintf.c: kptr_restrict: fix pK-error in SysRq show-all-timers(Q)Dan Rosenberg
When using ALT+SysRq+Q all the pointers are replaced with "pK-error" like this: [23153.208033] .base: pK-error with echo h > /proc/sysrq-trigger it works: [23107.776363] .base: ffff88023e60d540 The intent behind this behavior was to return "pK-error" in cases where the %pK format specifier was used in interrupt context, because the CAP_SYSLOG check wouldn't be meaningful. Clearly this should only apply when kptr_restrict is actually enabled though. Reported-by: Stevie Trujillo <stevie.trujillo@gmail.com> Signed-off-by: Dan Rosenberg <dan.j.rosenberg@gmail.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-30lib/vsprintf.c: remind people to update Documentation/printk-formats.txt ↵Andrew Morton
when adding printk formats Cc: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-30vsprintf: add %pMR for Bluetooth MAC addressAndrei Emeltchenko
Bluetooth uses mostly LE byte order which is reversed for visual interpretation. Currently in Bluetooth in use unsafe batostr function. This is a slightly modified version of Joe's patch (sent Sat, Dec 4, 2010). Signed-off-by: Andrei Emeltchenko <andrei.emeltchenko@intel.com> Cc: Joe Perches <joe@perches.com> Cc: Marcel Holtmann <marcel@holtmann.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-30Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linusLinus Torvalds
Pull MIPS updates from Ralf Baechle: "More hardware support across the field including a bunch of device drivers. The highlight however really are further steps towards device tree. This has been sitting in -next for ages. All MIPS _defconfigs have been tested to boot or where I don't have hardware available, to at least build fine." * 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus: (77 commits) MIPS: Loongson 1B: Add defconfig MIPS: Loongson 1B: Add board support MIPS: Netlogic: early console fix MIPS: Netlogic: Fix indentation of smpboot.S MIPS: Netlogic: remove cpu_has_dc_aliases define for XLP MIPS: Netlogic: Remove unused pcibios_fixups MIPS: Netlogic: Add XLP SoC devices in FDT MIPS: Netlogic: Add IRQ mappings for more devices MIPS: Netlogic: USB support for XLP MIPS: Netlogic: XLP PCIe controller support. MIPS: Netlogic: Platform changes for XLR/XLS I2C MIPS: Netlogic: Platform NAND/NOR flash support MIPS: Netlogic: Platform changes for XLS USB MIPS: Netlogic: Remove NETLOGIC_ prefix MIPS: Netlogic: SMP wakeup code update MIPS: Netlogic: Update comments in smpboot.S MIPS: BCM63XX: Add 96328avng reference board MIPS: Expose PCIe drivers for MIPS MIPS: BCM63XX: Add PCIe Support for BCM6328 MIPS: BCM63XX: Move the PCI initialization into its own function ...
2012-07-30Merge branch 'for-linus-for-3.6-rc1' of ↵Linus Torvalds
git://git.linaro.org/people/mszyprowski/linux-dma-mapping Pull DMA-mapping updates from Marek Szyprowski: "Those patches are continuation of my earlier work. They contains extensions to DMA-mapping framework to remove limitation of the current ARM implementation (like limited total size of DMA coherent/write combine buffers), improve performance of buffer sharing between devices (attributes to skip cpu cache operations or creation of additional kernel mapping for some specific use cases) as well as some unification of the common code for dma_mmap_attrs() and dma_mmap_coherent() functions. All extensions have been implemented and tested for ARM architecture." * 'for-linus-for-3.6-rc1' of git://git.linaro.org/people/mszyprowski/linux-dma-mapping: ARM: dma-mapping: add support for DMA_ATTR_SKIP_CPU_SYNC attribute common: DMA-mapping: add DMA_ATTR_SKIP_CPU_SYNC attribute ARM: dma-mapping: add support for dma_get_sgtable() common: dma-mapping: introduce dma_get_sgtable() function ARM: dma-mapping: add support for DMA_ATTR_NO_KERNEL_MAPPING attribute common: DMA-mapping: add DMA_ATTR_NO_KERNEL_MAPPING attribute common: dma-mapping: add support for generic dma_mmap_* calls ARM: dma-mapping: fix error path for memory allocation failure ARM: dma-mapping: add more sanity checks in arm_dma_mmap() ARM: dma-mapping: remove custom consistent dma region mm: vmalloc: use const void * for caller argument scatterlist: add sg_alloc_table_from_pages function
2012-07-30scatterlist: add sg_alloc_table_from_pages functionTomasz Stanislawski
This patch adds a new constructor for an sg table. The table is constructed from an array of struct pages. All contiguous chunks of the pages are merged into a single sg nodes. A user may provide an offset and a size of a buffer if the buffer is not page-aligned. The function is dedicated for DMABUF exporters which often perform conversion from an page array to a scatterlist. Moreover the scatterlist should be squashed in order to save memory and to speed-up the process of DMA mapping using dma_map_sg. The code is based on the patch 'v4l: vb2-dma-contig: add support for scatterlist in userptr mode' and hints from Laurent Pinchart. Signed-off-by: Tomasz Stanislawski <t.stanislaws@samsung.com> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> CC: Andrew Morton <akpm@linux-foundation.org>
2012-07-24Merge branch 'for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial Pull trivial tree from Jiri Kosina: "Trivial updates all over the place as usual." * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (29 commits) Fix typo in include/linux/clk.h . pci: hotplug: Fix typo in pci iommu: Fix typo in iommu video: Fix typo in drivers/video Documentation: Add newline at end-of-file to files lacking one arm,unicore32: Remove obsolete "select MISC_DEVICES" module.c: spelling s/postition/position/g cpufreq: Fix typo in cpufreq driver trivial: typo in comment in mksysmap mach-omap2: Fix typo in debug message and comment scsi: aha152x: Fix sparse warning and make printing pointer address more portable. Change email address for Steve Glendinning Btrfs: fix typo in convert_extent_bit via: Remove bogus if check netprio_cgroup.c: fix comment typo backlight: fix memory leak on obscure error path Documentation: asus-laptop.txt references an obsolete Kconfig item Documentation: ManagementStyle: fixed typo mm/vmscan: cleanup comment error in balance_pgdat mm: cleanup on the comments of zone_reclaim_stat ...
2012-07-24Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-nextLinus Torvalds
Pull networking changes from David S Miller: 1) Remove the ipv4 routing cache. Now lookups go directly into the FIB trie and use prebuilt routes cached there. No more garbage collection, no more rDOS attacks on the routing cache. Instead we now get predictable and consistent performance, no matter what the pattern of traffic we service. This has been almost 2 years in the making. Special thanks to Julian Anastasov, Eric Dumazet, Steffen Klassert, and others who have helped along the way. I'm sure that with a change of this magnitude there will be some kind of fallout, but such things ought the be simple to fix at this point. Luckily I'm not European so I'll be around all of August to fix things :-) The major stages of this work here are each fronted by a forced merge commit whose commit message contains a top-level description of the motivations and implementation issues. 2) Pre-demux of established ipv4 TCP sockets, saves a route demux on input. 3) TCP SYN/ACK performance tweaks from Eric Dumazet. 4) Add namespace support for netfilter L4 conntrack helpers, from Gao Feng. 5) Add config mechanism for Energy Efficient Ethernet to ethtool, from Yuval Mintz. 6) Remove quadratic behavior from /proc/net/unix, from Eric Dumazet. 7) Support for connection tracker helpers in userspace, from Pablo Neira Ayuso. 8) Allow userspace driven TX load balancing functions in TEAM driver, from Jiri Pirko. 9) Kill off NLMSG_PUT and RTA_PUT macros, more gross stuff with embedded gotos. 10) TCP Small Queues, essentially minimize the amount of TCP data queued up in the packet scheduler layer. Whereas the existing BQL (Byte Queue Limits) limits the pkt_sched --> netdevice queuing levels, this controls the TCP --> pkt_sched queueing levels. From Eric Dumazet. 11) Reduce the number of get_page/put_page ops done on SKB fragments, from Alexander Duyck. 12) Implement protection against blind resets in TCP (RFC 5961), from Eric Dumazet. 13) Support the client side of TCP Fast Open, basically the ability to send data in the SYN exchange, from Yuchung Cheng. Basically, the sender queues up data with a sendmsg() call using MSG_FASTOPEN, then they do the connect() which emits the queued up fastopen data. 14) Avoid all the problems we get into in TCP when timers or PMTU events hit a locked socket. The TCP Small Queues changes added a tcp_release_cb() that allows us to queue work up to the release_sock() caller, and that's what we use here too. From Eric Dumazet. 15) Zero copy on TX support for TUN driver, from Michael S. Tsirkin. * git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1870 commits) genetlink: define lockdep_genl_is_held() when CONFIG_LOCKDEP r8169: revert "add byte queue limit support". ipv4: Change rt->rt_iif encoding. net: Make skb->skb_iif always track skb->dev ipv4: Prepare for change of rt->rt_iif encoding. ipv4: Remove all RTCF_DIRECTSRC handliing. ipv4: Really ignore ICMP address requests/replies. decnet: Don't set RTCF_DIRECTSRC. net/ipv4/ip_vti.c: Fix __rcu warnings detected by sparse. ipv4: Remove redundant assignment rds: set correct msg_namelen openvswitch: potential NULL deref in sample() tcp: dont drop MTU reduction indications bnx2x: Add new 57840 device IDs tcp: avoid oops in tcp_metrics and reset tcpm_stamp niu: Change niu_rbr_fill() to use unlikely() to check niu_rbr_add_page() return value niu: Fix to check for dma mapping errors. net: Fix references to out-of-scope variables in put_cmsg_compat() net: ethernet: davinci_emac: add pm_runtime support net: ethernet: davinci_emac: Remove unnecessary #include ...
2012-07-23Merge tag 'please-pull-misc-3.6' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux Pull misc Itanium fixes from Tony Luck. * tag 'please-pull-misc-3.6' of git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux: debug: Do not permit CONFIG_DEBUG_STACK_USAGE=y on IA64 or PARISC [IA64] Port OOM changes to ia64_do_page_fault
2012-07-23Merge branch 'next' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security Pull security subsystem updates from James Morris: "Nothing groundbreaking for this kernel, just cleanups and fixes, and a couple of Smack enhancements." * 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security: (21 commits) Smack: Maintainer Record Smack: don't show empty rules when /smack/load or /smack/load2 is read Smack: user access check bounds Smack: onlycap limits on CAP_MAC_ADMIN Smack: fix smack_new_inode bogosities ima: audit is compiled only when enabled ima: ima_initialized is set only if successful ima: add policy for pseudo fs ima: remove unused cleanup functions ima: free securityfs violations file ima: use full pathnames in measurement list security: Fix nommu build. samples: seccomp: add .gitignore for untracked executables tpm: check the chip reference before using it TPM: fix memleak when register hardware fails TPM: chip disabled state erronously being reported as error MAINTAINERS: TPM maintainers' contacts update Merge branches 'next-queue' and 'next' into next Remove unused code from MPI library Revert "crypto: GnuPG based MPI lib - additional sources (part 4)" ...
2012-07-23of/lib: Allow scripts/dtc/libfdt to be used from kernel codeDavid Daney
libfdt is part of the device tree support in scripts/dtc/libfdt. For some platforms that use the Device Tree, we want to be able to edit the flattened device tree form. We don't want to burden kernel builds that do not require it, so we gate compilation of libfdt files with CONFIG_LIBFDT. So if it is needed, you need to do this in your Kconfig: select LIBFDT And in the Makefile of the code using libfdt something like: ccflags-y := -I$(src)/../../../scripts/dtc/libfdt Signed-off-by: David Daney <david.daney@cavium.com> Cc: linux-mips@linux-mips.org Cc: devicetree-discuss@lists.ozlabs.org Cc: Grant Likely <grant.likely@secretlab.ca> Cc: linux-kernel@vger.kernel.org Acked-by: Rob Herring <rob.herring@calxeda.com> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2012-07-22Merge branch 'core-rcu-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull RCU changes from Ingo Molnar: "Quoting from Paul, the major features of this series are: 1. Preventing latency spikes of more than 200 microseconds for kernels built with NR_CPUS=4096, which is reportedly becoming the default for some distros. This is a first step, as it does not help with systems that actually -have- 4096 CPUs (work on this case is in progress, but is not yet ready for mainline). This category also includes improving concurrency of rcu_barrier(), placed here due to conflicts. Posted to LKML at: https://lkml.org/lkml/2012/6/22/381 Note that patches 18-22 of that series have been defered to 3.7, as they have not yet proven themselves to be mainline-ready (and yes, these are the ones intended to get rid of RCU's latency spikes for systems that actually have 4096 CPUs). 2. Updates to documentation and rcutorture fixes, the latter category including improvements to rcu_barrier() testing. Posted to LKML at http://lkml.indiana.edu/hypermail/linux/kernel/1206.1/04094.html. 3. Miscellaneous fixes posted to LKML at: https://lkml.org/lkml/2012/6/22/500 with the exception of the last commit, which was posted here: http://www.gossamer-threads.com/lists/linux/kernel/1561830 4. RCU_FAST_NO_HZ fixes and improvements. Posted to LKML at: http://lkml.indiana.edu/hypermail/linux/kernel/1206.1/00006.html http://www.gossamer-threads.com/lists/linux/kernel/1561833 The first four patches of the first series went into 3.5 to fix a regression. 5. Code-style fixes. These were posted to LKML at http://lkml.indiana.edu/hypermail/linux/kernel/1205.2/01180.html http://lkml.indiana.edu/hypermail/linux/kernel/1205.2/01181.html" * 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (48 commits) rcu: Fix broken strings in RCU's source code. rcu: Fix code-style issues involving "else" rcu: Introduce check for callback list/count mismatch rcu: Make RCU_FAST_NO_HZ respect nohz= boot parameter rcu: Fix qlen_lazy breakage rcu: Round FAST_NO_HZ lazy timeout to nearest second rcu: The rcu_needs_cpu() function is not a quiescent state rcu: Dump only the current CPU's buffers for idle-entry/exit warnings rcu: Add check for CPUs going offline with callbacks queued rcu: Disable preemption in rcu_blocking_is_gp() rcu: Prevent uninitialized string in RCU CPU stall info rcu: Fix rcu_is_cpu_idle() #ifdef in TINY_RCU rcu: Split RCU core processing out of __call_rcu() rcu: Prevent __call_rcu() from invoking RCU core on offline CPUs rcu: Make __call_rcu() handle invocation from idle rcu: Remove function versions of __kfree_rcu and __is_kfree_rcu_offset rcu: Consolidate tree/tiny __rcu_read_{,un}lock() implementations rcu: Remove return value from rcu_assign_pointer() key: Remove extraneous parentheses from rcu_assign_keypointer() rcu: Remove return value from RCU_INIT_POINTER() ...
2012-07-19Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netDavid S. Miller
Conflicts: drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
2012-07-19debug: Do not permit CONFIG_DEBUG_STACK_USAGE=y on IA64 or PARISCTony Luck
The stack_not_used() function in <linux/sched.h> assumes that stacks grow downwards. This is not true on IA64 or PARISC, so this function would walk off in the wrong direction and into the weeds. Found on IA64 because of a compilation failure with recursive dependencies on IA64_TASKSIZE and IA64_THREAD_INFO_SIZE. Fixing the code is possible, but should be combined with other infrastructure additions to set up the "canary" at the end of the stack. Reported-by: Fengguang Wu <fengguang.wu@intel.com> (failed allmodconfig build) Signed-off-by: Tony Luck <tony.luck@intel.com>
2012-07-09Merge tag 'iommu-fixes-v3.5-rc5' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu Pull IOMMU fixes from Joerg Roedel: "The patches fix several issues in the AMD IOMMU driver, the NVidia SMMU driver, and the DMA debug code. The most important fix for the AMD IOMMU solves a problem with SR-IOV devices where virtual functions did not work with IOMMU enabled. The NVidia SMMU patch fixes a possible sleep while spin-lock situation (queued the small fix for v3.5, a better but more intrusive fix is coming for v3.6). The DMA debug patches fix a possible data corruption issue due to bool vs u32 usage." * tag 'iommu-fixes-v3.5-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu: iommu/amd: fix type bug in flush code dma-debug: debugfs_create_bool() takes a u32 pointer iommu/tegra: smmu: Fix unsleepable memory allocation iommu/amd: Initialize dma_ops for hotplug and sriov devices iommu/amd: Fix missing iommu_shutdown initialization in passthrough mode
2012-07-06rcu: Fix broken strings in RCU's source code.Paul E. McKenney
Although the C language allows you to break strings across lines, doing this makes it hard for people to find the Linux kernel code corresponding to a given console message. This commit therefore fixes broken strings throughout RCU's source code. Suggested-by: Josh Triplett <josh@joshtriplett.org> Suggested-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2012-07-02dma-debug: debugfs_create_bool() takes a u32 pointerDan Carpenter
Even though it has "bool" in the name, you have pass a u32 pointer to debugfs_create_bool(). Otherwise you get memory corruption in write_file_bool(). Fortunately in this case the corruption happens in an alignment hole between variables so it doesn't cause any problems. Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
2012-06-29netlink: add netlink_kernel_cfg parameter to netlink_kernel_createPablo Neira Ayuso
This patch adds the following structure: struct netlink_kernel_cfg { unsigned int groups; void (*input)(struct sk_buff *skb); struct mutex *cb_mutex; }; That can be passed to netlink_kernel_create to set optional configurations for netlink kernel sockets. I've populated this structure by looking for NULL and zero parameters at the existing code. The remaining parameters that always need to be set are still left in the original interface. That includes optional parameters for the netlink socket creation. This allows easy extensibility of this interface in the future. This patch also adapts all callers to use this new interface. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2012-06-29Merge branch 'master' into for-nextJiri Kosina
Conflicts: include/linux/mmzone.h Synced with Linus' tree so that trivial patch can be applied on top of up-to-date code properly. Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
2012-06-28lib: correct link to the original source for div64_u64Akinobu Mita
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: Jiri Kosina <trivial@kernel.org> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2012-06-20fault-inject: avoid call to random32() if fault injection is disabledAnton Blanchard
After enabling CONFIG_FAILSLAB I noticed random32 in profiles even if slub fault injection wasn't enabled at runtime. should_fail forces a comparison against random32() even if probability is 0: if (attr->probability <= random32() % 100) return false; Add a check up front for probability == 0 and avoid all of the more complicated checks. Signed-off-by: Anton Blanchard <anton@samba.org> Acked-by: Akinobu Mita <akinobu.mita@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-06-15Merge branch 'core-urgent-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull core updates (RCU and locking) from Ingo Molnar: "Most of the diffstat comes from the RCU slow boot regression fixes, but there's also a debuggability improvements/fixes." * 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: memblock: Document memblock_is_region_{memory,reserved}() rcu: Precompute RCU_FAST_NO_HZ timer offsets rcu: Move RCU_FAST_NO_HZ per-CPU variables to rcu_dynticks structure rcu: Update RCU_FAST_NO_HZ tracing for lazy callbacks rcu: RCU_FAST_NO_HZ detection of callback adoption spinlock: Indicate that a lockup is only suspected kdump: Execute kmsg_dump(KMSG_DUMP_PANIC) after smp_send_stop() panic: Make panic_on_oops configurable
2012-06-10Merge commit 'v3.5-rc2' into nextJames Morris
2012-06-09lib: Fix possible deadlock in flexible proportion codeJan Kara
When percpu counter function in fprop_new_period() is interrupted by an interrupt while holding counter lock, it can cause deadlock when the interrupt wants to take the lock as well. Fix the problem by disabling interrupts when calling percpu counter functions. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
2012-06-09lib: Proportions with flexible periodJan Kara
Implement code computing proportions of events of different type (like code in lib/proportions.c) but allowing periods to have different lengths. This allows us to have aging periods of fixed wallclock time which gives better proportion estimates given the hugely varying throughput of different devices - previous measuring of aging period by number of events has the problem that a reasonable period length for a system with low-end USB stick is not a reasonable period length for a system with high-end storage array resulting either in too slow proportion updates or too fluctuating proportion updates. Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
2012-06-07btree: catch NULL value before it does harmJoern Engel
Storing NULL values in the btree is illegal and can lead to memory corruption and possible other fun as well. Catch it on insert, instead of waiting for the inevitable. Signed-off-by: Joern Engel <joern@logfs.org> Signed-off-by: Roland Dreier <roland@purestorage.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-06-07btree: fix tree corruption in btree_get_prev()Roland Dreier
The memory the parameter __key points to is used as an iterator in btree_get_prev(), so if we save off a bkey() pointer in retry_key and then assign that to __key, we'll end up corrupting the btree internals when we do eg longcpy(__key, bkey(geo, node, i), geo->keylen); to return the key value. What we should do instead is use longcpy() to copy the key value that retry_key points to __key. This can cause a btree to get corrupted by seemingly read-only operations such as btree_for_each_safe. [akpm@linux-foundation.org: avoid the double longcpy()] Signed-off-by: Roland Dreier <roland@purestorage.com> Acked-by: Joern Engel <joern@logfs.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-06-06Merge tag 'md-3.5-fixes' of git://neil.brown.name/mdLinus Torvalds
Pull two md fixes from NeilBrown: "One sparse-warning fix, one bugfix for 3.4-stable" * tag 'md-3.5-fixes' of git://neil.brown.name/md: md: raid1/raid10: fix problem with merge_bvec_fn lib/raid6: fix sparse warnings in recovery functions
2012-06-06spinlock: Indicate that a lockup is only suspectedChristian Borntraeger
On an over-committed KVM system we got a: "BUG: spinlock lockup on CPU#2, swapper/2/0" message on the heavily contended virtio blk spinlock. While we might want to reconsider the locking of virtio-blk (lock is held while switching to the host) this patch tries to make the message clearer: the lockup is only suspected. Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1338283124-7063-1-git-send-email-borntraeger@de.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-06-06Merge branch 'core/debug' into core/urgentIngo Molnar
Merge two debugging patchlets that were waiting for preparatory commits to hit upstream. Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-06-05radix-tree: fix contiguous iteratorKonstantin Khlebnikov
This patch fixes bug in macro radix_tree_for_each_contig(). If radix_tree_next_slot() sees NULL in next slot it returns NULL, but following radix_tree_next_chunk() switches iterating into next chunk. As result iterating becomes non-contiguous and breaks vfs "splice" and all its users. Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Reported-and-bisected-by: Hans de Bruin <jmdebruin@xmsnet.nl> Reported-and-bisected-by: Ondrej Zary <linux@rainbow-software.org> Reported-bisected-and-tested-by: Toralf Förster <toralf.foerster@gmx.de> Link: https://lkml.org/lkml/2012/6/5/64 Cc: stable <stable@vger.kernel.org> # 3.4.x Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-06-02Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netLinus Torvalds
Pull networking updates from David Miller: 1) Make syn floods consume significantly less resources by a) Not pre-COW'ing routing metrics for SYN/ACKs b) Mirroring the device queue mapping of the SYN for the SYN/ACK reply. Both from Eric Dumazet. 2) Fix calculation errors in Byte Queue Limiting, from Hiroaki SHIMODA. 3) Validate the length requested when building a paged SKB for a socket, so we don't overrun the page vector accidently. From Jason Wang. 4) When netlabel is disabled, we abort all IP option processing when we see a CIPSO option. This isn't the right thing to do, we should simply skip over it and continue processing the remaining options (if any). Fix from Paul Moore. 5) SRIOV fixes for the mellanox driver from Jack orgenstein and Marcel Apfelbaum. 6) 8139cp enables the receiver before the ring address is properly programmed, which potentially lets the device crap over random memory. Fix from Jason Wang. 7) e1000/e1000e fixes for i217 RST handling, and an improper buffer address reference in jumbo RX frame processing from Bruce Allan and Sebastian Andrzej Siewior, respectively. * git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: fec_mpc52xx: fix timestamp filtering mcs7830: Implement link state detection e1000e: fix Rapid Start Technology support for i217 e1000: look into the page instead of skb->data for e1000_tbi_adjust_stats() r8169: call netif_napi_del at errpaths and at driver unload tcp: reflect SYN queue_mapping into SYNACK packets tcp: do not create inetpeer on SYNACK message 8139cp/8139too: terminate the eeprom access with the right opmode 8139cp: set ring address before enabling receiver cipso: handle CIPSO options correctly when NetLabel is disabled net: sock: validate data_len before allocating skb in sock_alloc_send_pskb() bql: Avoid possible inconsistent calculation. bql: Avoid unneeded limit decrement. bql: Fix POSDIFF() to integer overflow aware. net/mlx4_core: Fix obscure mlx4_cmd_box parameter in QUERY_DEV_CAP net/mlx4_core: Check port out-of-range before using in mlx4_slave_cap net/mlx4_core: Fixes for VF / Guest startup flow net/mlx4_en: Fix improper use of "port" parameter in mlx4_en_event net/mlx4_core: Fix number of EQs used in ICM initialisation net/mlx4_core: Fix the slave_id out-of-range test in mlx4_eq_int
2012-05-31Merge branch 'akpm' (Andrew's patch-bomb)Linus Torvalds
Merge misc patches from Andrew Morton: - the "misc" tree - stuff from all over the map - checkpatch updates - fatfs - kmod changes - procfs - cpumask - UML - kexec - mqueue - rapidio - pidns - some checkpoint-restore feature work. Reluctantly. Most of it delayed a release. I'm still rather worried that we don't have a clear roadmap to completion for this work. * emailed from Andrew Morton <akpm@linux-foundation.org>: (78 patches) kconfig: update compression algorithm info c/r: prctl: add ability to set new mm_struct::exe_file c/r: prctl: extend PR_SET_MM to set up more mm_struct entries c/r: procfs: add arg_start/end, env_start/end and exit_code members to /proc/$pid/stat syscalls, x86: add __NR_kcmp syscall fs, proc: introduce /proc/<pid>/task/<tid>/children entry sysctl: make kernel.ns_last_pid control dependent on CHECKPOINT_RESTORE aio/vfs: cleanup of rw_copy_check_uvector() and compat_rw_copy_check_uvector() eventfd: change int to __u64 in eventfd_signal() fs/nls: add Apple NLS pidns: make killed children autoreap pidns: use task_active_pid_ns in do_notify_parent rapidio/tsi721: add DMA engine support rapidio: add DMA engine support for RIO data transfers ipc/mqueue: add rbtree node caching support tools/selftests: add mq_perf_tests ipc/mqueue: strengthen checks on mqueue creation ipc/mqueue: correct mq_attr_ok test ipc/mqueue: improve performance of send/recv selftests: add mq_open_tests ...
2012-05-31vsprintf: further optimize decimal conversionDenys Vlasenko
Previous code was using optimizations which were developed to work well even on narrow-word CPUs (by today's standards). But Linux runs only on 32-bit and wider CPUs. We can use that. First: using 32x32->64 multiply and trivial 32-bit shift, we can correctly divide by 10 much larger numbers, and thus we can print groups of 9 digits instead of groups of 5 digits. Next: there are two algorithms to print larger numbers. One is generic: divide by 1000000000 and repeatedly print groups of (up to) 9 digits. It's conceptually simple, but requires an (unsigned long long) / 1000000000 division. Second algorithm splits 64-bit unsigned long long into 16-bit chunks, manipulates them cleverly and generates groups of 4 decimal digits. It so happens that it does NOT require long long division. If long is > 32 bits, division of 64-bit values is relatively easy, and we will use the first algorithm. If long long is > 64 bits (strange architecture with VERY large long long), second algorithm can't be used, and we again use the first one. Else (if long is 32 bits and long long is 64 bits) we use second one. And third: there is a simple optimization which takes fast path not only for zero as was done before, but for all one-digit numbers. In all tested cases new code is faster than old one, in many cases by 30%, in few cases by more than 50% (for example, on x86-32, conversion of 12345678). Code growth is ~0 in 32-bit case and ~130 bytes in 64-bit case. This patch is based upon an original from Michal Nazarewicz. [akpm@linux-foundation.org: checkpatch fixes] Signed-off-by: Michal Nazarewicz <mina86@mina86.com> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com> Cc: Douglas W Jones <jones@cs.uiowa.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>