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* lockdep: allow instrumenting lockdep.c with KMSANAlexander Potapenko2022-12-111-1/+0
| | | | | | | | | | | | | | | | | | | | | Lockdep and KMSAN used to play badly together, causing deadlocks when KMSAN instrumentation of lockdep.c called lockdep functions recursively. Looks like this is no more the case, and a kernel can run (yet slower) with both KMSAN and lockdep enabled. This patch should fix false positives on wq_head->lock->dep_map, which KMSAN used to consider uninitialized because of lockdep.c not being instrumented. Link: https://lore.kernel.org/lkml/Y3b9AAEKp2Vr3e6O@sol.localdomain/ Link: https://lkml.kernel.org/r/20221128094541.2645890-1-glider@google.com Signed-off-by: Alexander Potapenko <glider@google.com> Reported-by: Eric Biggers <ebiggers@kernel.org> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Marco Elver <elver@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
* kmsan: disable instrumentation of unsupported common kernel codeAlexander Potapenko2022-10-031-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | EFI stub cannot be linked with KMSAN runtime, so we disable instrumentation for it. Instrumenting kcov, stackdepot or lockdep leads to infinite recursion caused by instrumentation hooks calling instrumented code again. Link: https://lkml.kernel.org/r/20220915150417.722975-13-glider@google.com Signed-off-by: Alexander Potapenko <glider@google.com> Reviewed-by: Marco Elver <elver@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrey Konovalov <andreyknvl@gmail.com> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Borislav Petkov <bp@alien8.de> Cc: Christoph Hellwig <hch@lst.de> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Eric Biggers <ebiggers@google.com> Cc: Eric Biggers <ebiggers@kernel.org> Cc: Eric Dumazet <edumazet@google.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Ilya Leoshkevich <iii@linux.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Kees Cook <keescook@chromium.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Petr Mladek <pmladek@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Vegard Nossum <vegard.nossum@oracle.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
* locking/ww_mutex: Implement rtmutex based ww_mutex API functionsPeter Zijlstra2021-08-171-1/+1
| | | | | | | | | | | Add the actual ww_mutex API functions which replace the mutex based variant on RT enabled kernels. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20210815211305.024057938@linutronix.de
* locking/spinlock: Provide RT variantThomas Gleixner2021-08-171-0/+1
| | | | | | | | | | Provide the actual locking functions which make use of the general and spinlock specific rtmutex code. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20210815211303.826621464@linutronix.de
* locking/rtmutex: Split API from implementationThomas Gleixner2021-08-171-1/+1
| | | | | | | | | | | Prepare for reusing the inner functions of rtmutex for RT lock substitutions: introduce kernel/locking/rtmutex_api.c and move them there. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20210815211302.726560996@linutronix.de
* locking/rtmutex: Move debug functions as inlines into common headerThomas Gleixner2021-03-291-2/+0
| | | | | | | | | | There is no value in having two header files providing just empty stubs and a C file which implements trivial debug functions which can just be inlined. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20210326153944.052454464@linutronix.de
* lockdep: report broken irq restorationMark Rutland2021-01-221-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We generally expect local_irq_save() and local_irq_restore() to be paired and sanely nested, and so local_irq_restore() expects to be called with irqs disabled. Thus, within local_irq_restore() we only trace irq flag changes when unmasking irqs. This means that a sequence such as: | local_irq_disable(); | local_irq_save(flags); | local_irq_enable(); | local_irq_restore(flags); ... is liable to break things, as the local_irq_restore() would mask irqs without tracing this change. Similar problems may exist for architectures whose arch_irq_restore() function depends on being called with irqs disabled. We don't consider such sequences to be a good idea, so let's define those as forbidden, and add tooling to detect such broken cases. This patch adds debug code to WARN() when raw_local_irq_restore() is called with irqs enabled. As raw_local_irq_restore() is expected to pair with raw_local_irq_save(), it should never be called with irqs enabled. To avoid the possibility of circular header dependencies between irqflags.h and bug.h, the warning is handled in a separate C file. The new code is all conditional on a new CONFIG_DEBUG_IRQFLAGS symbol which is independent of CONFIG_TRACE_IRQFLAGS. As noted above such cases will confuse lockdep, so CONFIG_DEBUG_LOCKDEP now selects CONFIG_DEBUG_IRQFLAGS. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20210111153707.10071-1-mark.rutland@arm.com
* kcsan: Make KCSAN compatible with lockdepMarco Elver2020-03-211-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We must avoid any recursion into lockdep if KCSAN is enabled on utilities used by lockdep. One manifestation of this is corruption of lockdep's IRQ trace state (if TRACE_IRQFLAGS), resulting in spurious warnings (see below). This commit fixes this by: 1. Using raw_local_irq{save,restore} in kcsan_setup_watchpoint(). 2. Disabling lockdep in kcsan_report(). Tested with: CONFIG_LOCKDEP=y CONFIG_DEBUG_LOCKDEP=y CONFIG_TRACE_IRQFLAGS=y This fix eliminates spurious warnings such as the following one: WARNING: CPU: 0 PID: 2 at kernel/locking/lockdep.c:4406 check_flags.part.0+0x101/0x220 Modules linked in: CPU: 0 PID: 2 Comm: kthreadd Not tainted 5.5.0-rc1+ #11 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 RIP: 0010:check_flags.part.0+0x101/0x220 <snip> Call Trace: lock_is_held_type+0x69/0x150 freezer_fork+0x20b/0x370 cgroup_post_fork+0x2c9/0x5c0 copy_process+0x2675/0x3b40 _do_fork+0xbe/0xa30 ? _raw_spin_unlock_irqrestore+0x40/0x50 ? match_held_lock+0x56/0x250 ? kthread_park+0xf0/0xf0 kernel_thread+0xa6/0xd0 ? kthread_park+0xf0/0xf0 kthreadd+0x321/0x3d0 ? kthread_create_on_cpu+0x130/0x130 ret_from_fork+0x3a/0x50 irq event stamp: 64 hardirqs last enabled at (63): [<ffffffff9a7995d0>] _raw_spin_unlock_irqrestore+0x40/0x50 hardirqs last disabled at (64): [<ffffffff992a96d2>] kcsan_setup_watchpoint+0x92/0x460 softirqs last enabled at (32): [<ffffffff990489b8>] fpu__copy+0xe8/0x470 softirqs last disabled at (30): [<ffffffff99048939>] fpu__copy+0x69/0x470 Reported-by: Qian Cai <cai@lca.pw> Signed-off-by: Marco Elver <elver@google.com> Acked-by: Alexander Potapenko <glider@google.com> Tested-by: Qian Cai <cai@lca.pw> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org>
* locking/rwsem: Merge rwsem.h and rwsem-xadd.c into rwsem.cWaiman Long2019-06-171-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Now we only have one implementation of rwsem. Even though we still use xadd to handle reader locking, we use cmpxchg for writer instead. So the filename rwsem-xadd.c is not strictly correct. Also no one outside of the rwsem code need to know the internal implementation other than function prototypes for two internal functions that are called directly from percpu-rwsem.c. So the rwsem-xadd.c and rwsem.h files are now merged into rwsem.c in the following order: <upper part of rwsem.h> <rwsem-xadd.c> <lower part of rwsem.h> <rwsem.c> The rwsem.h file now contains only 2 function declarations for __up_read() and __down_read(). This is a code relocation patch with no code change at all except making __up_read() and __down_read() non-static functions so they can be used by percpu-rwsem.c. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Waiman Long <longman@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: Will Deacon <will.deacon@arm.com> Cc: huang ying <huang.ying.caritas@gmail.com> Link: https://lkml.kernel.org/r/20190520205918.22251-5-longman@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* locking/lock_events: Make lock_events available for all archs & other locksWaiman Long2019-04-101-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The QUEUED_LOCK_STAT option to report queued spinlocks event counts was previously allowed only on x86 architecture. To make the locking event counting code more useful, it is now renamed to a more generic LOCK_EVENT_COUNTS config option. This new option will be available to all the architectures that use qspinlock at the moment. Other locking code can now start to use the generic locking event counting code by including lock_events.h and put the new locking event names into the lock_events_list.h header file. My experience with lock event counting is that it gives valuable insight on how the locking code works and what can be done to make it better. I would like to extend this benefit to other locking code like mutex and rwsem in the near future. The PV qspinlock specific code will stay in qspinlock_stat.h. The locking event counters will now reside in the <debugfs>/lock_event_counts directory. Signed-off-by: Waiman Long <longman@redhat.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Davidlohr Bueso <dbueso@suse.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Borislav Petkov <bp@alien8.de> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: Will Deacon <will.deacon@arm.com> Link: http://lkml.kernel.org/r/20190404174320.22416-9-longman@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* locking/rwsem: Remove rwsem-spinlock.c & use rwsem-xadd.c for all archsWaiman Long2019-04-031-3/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, we have two different implementation of rwsem: 1) CONFIG_RWSEM_GENERIC_SPINLOCK (rwsem-spinlock.c) 2) CONFIG_RWSEM_XCHGADD_ALGORITHM (rwsem-xadd.c) As we are going to use a single generic implementation for rwsem-xadd.c and no architecture-specific code will be needed, there is no point in keeping two different implementations of rwsem. In most cases, the performance of rwsem-spinlock.c will be worse. It also doesn't get all the performance tuning and optimizations that had been implemented in rwsem-xadd.c over the years. For simplication, we are going to remove rwsem-spinlock.c and make all architectures use a single implementation of rwsem - rwsem-xadd.c. All references to RWSEM_GENERIC_SPINLOCK and RWSEM_XCHGADD_ALGORITHM in the code are removed. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Waiman Long <longman@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Borislav Petkov <bp@alien8.de> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: Will Deacon <will.deacon@arm.com> Cc: linux-arm-kernel@lists.infradead.org Cc: linux-c6x-dev@linux-c6x.org Cc: linux-m68k@lists.linux-m68k.org Cc: linux-riscv@lists.infradead.org Cc: linux-um@lists.infradead.org Cc: linux-xtensa@linux-xtensa.org Cc: linuxppc-dev@lists.ozlabs.org Cc: nios2-dev@lists.rocketboards.org Cc: openrisc@lists.librecores.org Cc: uclinux-h8-devel@lists.sourceforge.jp Link: https://lkml.kernel.org/r/20190322143008.21313-3-longman@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* License cleanup: add SPDX GPL-2.0 license identifier to files with no licenseGreg Kroah-Hartman2017-11-021-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* locking/ww_mutex: Begin kselftests for ww_mutexChris Wilson2017-01-141-0/+1
| | | | | | | | | | | | | | Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Maarten Lankhorst <dev@mblankhorst.nl> Cc: Nicolai Hähnle <nhaehnle@gmail.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20161201114711.28697-4-chris@chris-wilson.co.uk Signed-off-by: Ingo Molnar <mingo@kernel.org>
* locking/lglock: Remove lglock implementationPeter Zijlstra2016-09-221-1/+0
| | | | | | | | | | | | It is now unused, remove it before someone else thinks its a good idea to use this. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* kernel: add kcov code coverageDmitry Vyukov2016-03-221-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | kcov provides code coverage collection for coverage-guided fuzzing (randomized testing). Coverage-guided fuzzing is a testing technique that uses coverage feedback to determine new interesting inputs to a system. A notable user-space example is AFL (http://lcamtuf.coredump.cx/afl/). However, this technique is not widely used for kernel testing due to missing compiler and kernel support. kcov does not aim to collect as much coverage as possible. It aims to collect more or less stable coverage that is function of syscall inputs. To achieve this goal it does not collect coverage in soft/hard interrupts and instrumentation of some inherently non-deterministic or non-interesting parts of kernel is disbled (e.g. scheduler, locking). Currently there is a single coverage collection mode (tracing), but the API anticipates additional collection modes. Initially I also implemented a second mode which exposes coverage in a fixed-size hash table of counters (what Quentin used in his original patch). I've dropped the second mode for simplicity. This patch adds the necessary support on kernel side. The complimentary compiler support was added in gcc revision 231296. We've used this support to build syzkaller system call fuzzer, which has found 90 kernel bugs in just 2 months: https://github.com/google/syzkaller/wiki/Found-Bugs We've also found 30+ bugs in our internal systems with syzkaller. Another (yet unexplored) direction where kcov coverage would greatly help is more traditional "blob mutation". For example, mounting a random blob as a filesystem, or receiving a random blob over wire. Why not gcov. Typical fuzzing loop looks as follows: (1) reset coverage, (2) execute a bit of code, (3) collect coverage, repeat. A typical coverage can be just a dozen of basic blocks (e.g. an invalid input). In such context gcov becomes prohibitively expensive as reset/collect coverage steps depend on total number of basic blocks/edges in program (in case of kernel it is about 2M). Cost of kcov depends only on number of executed basic blocks/edges. On top of that, kernel requires per-thread coverage because there are always background threads and unrelated processes that also produce coverage. With inlined gcov instrumentation per-thread coverage is not possible. kcov exposes kernel PCs and control flow to user-space which is insecure. But debugfs should not be mapped as user accessible. Based on a patch by Quentin Casasnovas. [akpm@linux-foundation.org: make task_struct.kcov_mode have type `enum kcov_mode'] [akpm@linux-foundation.org: unbreak allmodconfig] [akpm@linux-foundation.org: follow x86 Makefile layout standards] Signed-off-by: Dmitry Vyukov <dvyukov@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Cc: syzkaller <syzkaller@googlegroups.com> Cc: Vegard Nossum <vegard.nossum@oracle.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Tavis Ormandy <taviso@google.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com> Cc: Kostya Serebryany <kcc@google.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Kees Cook <keescook@google.com> Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: David Drysdale <drysdale@google.com> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge branch 'for-linus' of ↵Linus Torvalds2015-09-051-2/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull vfs updates from Al Viro: "In this one: - d_move fixes (Eric Biederman) - UFS fixes (me; locking is mostly sane now, a bunch of bugs in error handling ought to be fixed) - switch of sb_writers to percpu rwsem (Oleg Nesterov) - superblock scalability (Josef Bacik and Dave Chinner) - swapon(2) race fix (Hugh Dickins)" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (65 commits) vfs: Test for and handle paths that are unreachable from their mnt_root dcache: Reduce the scope of i_lock in d_splice_alias dcache: Handle escaped paths in prepend_path mm: fix potential data race in SyS_swapon inode: don't softlockup when evicting inodes inode: rename i_wb_list to i_io_list sync: serialise per-superblock sync operations inode: convert inode_sb_list_lock to per-sb inode: add hlist_fake to avoid the inode hash lock in evict writeback: plug writeback at a high level change sb_writers to use percpu_rw_semaphore shift percpu_counter_destroy() into destroy_super_work() percpu-rwsem: kill CONFIG_PERCPU_RWSEM percpu-rwsem: introduce percpu_rwsem_release() and percpu_rwsem_acquire() percpu-rwsem: introduce percpu_down_read_trylock() document rwsem_release() in sb_wait_write() fix the broken lockdep logic in __sb_start_write() introduce __sb_writers_{acquired,release}() helpers ufs_inode_get{frag,block}(): get rid of 'phys' argument ufs_getfrag_block(): tidy up a bit ...
| * percpu-rwsem: kill CONFIG_PERCPU_RWSEMOleg Nesterov2015-08-151-2/+1
| | | | | | | | | | | | | | Remove CONFIG_PERCPU_RWSEM, the next patch adds the unconditional user of percpu_rw_semaphore. Signed-off-by: Oleg Nesterov <oleg@redhat.com>
* | rtmutex: Delete scriptable testerDavidlohr Bueso2015-07-201-1/+0
|/ | | | | | | | | | | | | | | | | | No one uses this anymore, and this is not the first time the idea of replacing it with a (now possible) userspace side. Lock stealing logic was removed long ago in when the lock was granted to the highest prio. Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Cc: Darren Hart <dvhart@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Mike Galbraith <umgwanakikbuti@gmail.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1435782588-4177-2-git-send-email-dave@stgolabs.net Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* locking/qrwlock: Rename QUEUE_RWLOCK to QUEUED_RWLOCKSWaiman Long2015-05-121-1/+1
| | | | | | | | | | | | | | | | | To be consistent with the queued spinlocks which use CONFIG_QUEUED_SPINLOCKS config parameter, the one for the queued rwlocks is now renamed to CONFIG_QUEUED_RWLOCKS. Signed-off-by: Waiman Long <Waiman.Long@hp.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Douglas Hatch <doug.hatch@hp.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Scott J Norton <scott.norton@hp.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1431367031-36697-1-git-send-email-Waiman.Long@hp.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* locking/pvqspinlock: Rename QUEUED_SPINLOCK to QUEUED_SPINLOCKSIngo Molnar2015-05-111-1/+1
| | | | | | | | | | | | | | | | | | | | Valentin Rothberg reported that we use CONFIG_QUEUED_SPINLOCKS in arch/x86/kernel/paravirt_patch_32.c, while the symbol is called CONFIG_QUEUED_SPINLOCK. (Note the extra 'S') But the typo was natural: the proper English term for such a generic object would be 'queued spinlocks' - so rename this and related symbols accordingly to the plural form. Reported-by: Valentin Rothberg <valentinrothberg@gmail.com> Cc: Douglas Hatch <doug.hatch@hp.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Scott J Norton <scott.norton@hp.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Waiman Long <Waiman.Long@hp.com> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* locking/qspinlock: Introduce a simple generic 4-byte queued spinlockWaiman Long2015-05-081-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch introduces a new generic queued spinlock implementation that can serve as an alternative to the default ticket spinlock. Compared with the ticket spinlock, this queued spinlock should be almost as fair as the ticket spinlock. It has about the same speed in single-thread and it can be much faster in high contention situations especially when the spinlock is embedded within the data structure to be protected. Only in light to moderate contention where the average queue depth is around 1-3 will this queued spinlock be potentially a bit slower due to the higher slowpath overhead. This queued spinlock is especially suit to NUMA machines with a large number of cores as the chance of spinlock contention is much higher in those machines. The cost of contention is also higher because of slower inter-node memory traffic. Due to the fact that spinlocks are acquired with preemption disabled, the process will not be migrated to another CPU while it is trying to get a spinlock. Ignoring interrupt handling, a CPU can only be contending in one spinlock at any one time. Counting soft IRQ, hard IRQ and NMI, a CPU can only have a maximum of 4 concurrent lock waiting activities. By allocating a set of per-cpu queue nodes and used them to form a waiting queue, we can encode the queue node address into a much smaller 24-bit size (including CPU number and queue node index) leaving one byte for the lock. Please note that the queue node is only needed when waiting for the lock. Once the lock is acquired, the queue node can be released to be used later. Signed-off-by: Waiman Long <Waiman.Long@hp.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Daniel J Blueman <daniel@numascale.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Douglas Hatch <doug.hatch@hp.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paolo Bonzini <paolo.bonzini@gmail.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com> Cc: Rik van Riel <riel@redhat.com> Cc: Scott J Norton <scott.norton@hp.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: virtualization@lists.linux-foundation.org Cc: xen-devel@lists.xenproject.org Link: http://lkml.kernel.org/r/1429901803-29771-2-git-send-email-Waiman.Long@hp.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* Merge branch 'for-linus' of ↵Linus Torvalds2015-02-111-4/+4
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux Pull s390 updates from Martin Schwidefsky: - The remaining patches for the z13 machine support: kernel build option for z13, the cache synonym avoidance, SMT support, compare-and-delay for spinloops and the CES5S crypto adapater. - The ftrace support for function tracing with the gcc hotpatch option. This touches common code Makefiles, Steven is ok with the changes. - The hypfs file system gets an extension to access diagnose 0x0c data in user space for performance analysis for Linux running under z/VM. - The iucv hvc console gets wildcard spport for the user id filtering. - The cacheinfo code is converted to use the generic infrastructure. - Cleanup and bug fixes. * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (42 commits) s390/process: free vx save area when releasing tasks s390/hypfs: Eliminate hypfs interval s390/hypfs: Add diagnose 0c support s390/cacheinfo: don't use smp_processor_id() in preemptible context s390/zcrypt: fixed domain scanning problem (again) s390/smp: increase maximum value of NR_CPUS to 512 s390/jump label: use different nop instruction s390/jump label: add sanity checks s390/mm: correct missing space when reporting user process faults s390/dasd: cleanup profiling s390/dasd: add locking for global_profile access s390/ftrace: hotpatch support for function tracing ftrace: let notrace function attribute disable hotpatching if necessary ftrace: allow architectures to specify ftrace compile options s390: reintroduce diag 44 calls for cpu_relax() s390/zcrypt: Add support for new crypto express (CEX5S) adapter. s390/zcrypt: Number of supported ap domains is not retrievable. s390/spinlock: add compare-and-delay to lock wait loops s390/tape: remove redundant if statement s390/hvc_iucv: add simple wildcard matches to the iucv allow filter ...
| * ftrace: allow architectures to specify ftrace compile optionsHeiko Carstens2015-01-291-4/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | If the kernel is compiled with function tracer support the -pg compile option is passed to gcc to generate extra code into the prologue of each function. This patch replaces the "open-coded" -pg compile flag with a CC_FLAGS_FTRACE makefile variable which architectures can override if a different option should be used for code generation. Acked-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
* | locking/mcs: Better differentiate between MCS variantsDavidlohr Bueso2015-01-141-1/+2
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | We have two flavors of the MCS spinlock: standard and cancelable (OSQ). While each one is independent of the other, we currently mix and match them. This patch: - Moves the OSQ code out of mcs_spinlock.h (which only deals with the traditional version) into include/linux/osq_lock.h. No unnecessary code is added to the more global header file, anything locks that make use of OSQ must include it anyway. - Renames mcs_spinlock.c to osq_lock.c. This file only contains osq code. - Introduces a CONFIG_LOCK_SPIN_ON_OWNER in order to only build osq_lock if there is support for it. Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Jason Low <jason.low2@hp.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mikulas Patocka <mpatocka@redhat.com> Cc: Waiman Long <Waiman.Long@hp.com> Link: http://lkml.kernel.org/r/1420573509-24774-5-git-send-email-dave@stgolabs.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
* locking/rwlocks: Introduce 'qrwlocks' - fair, queued rwlocksWaiman Long2014-06-061-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This rwlock uses the arch_spin_lock_t as a waitqueue, and assuming the arch_spin_lock_t is a fair lock (ticket,mcs etc..) the resulting rwlock is a fair lock. It fits in the same 8 bytes as the regular rwlock_t by folding the reader and writer count into a single integer, using the remaining 4 bytes for the arch_spinlock_t. Architectures that can single-copy adress bytes can optimize queue_write_unlock() with a 0 write to the LSB (the write count). Performance as measured by Davidlohr Bueso (rwlock_t -> qrwlock_t): +--------------+-------------+---------------+ | Workload | #users | delta | +--------------+-------------+---------------+ | alltests | > 1400 | -4.83% | | custom | 0-100,> 100 | +1.43%,-1.57% | | high_systime | > 1000 | -2.61 | | shared | all | +0.32 | +--------------+-------------+---------------+ http://www.stgolabs.net/qrwlock-stuff/aim7-results-vs-rwsem_optsin/ Signed-off-by: Waiman Long <Waiman.Long@hp.com> [peterz: near complete rewrite] Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: "Paul E.McKenney" <paulmck@linux.vnet.ibm.com> Cc: linux-arch@vger.kernel.org Cc: linux-kernel@vger.kernel.org Link: http://lkml.kernel.org/n/tip-gac1nnl3wvs2ij87zv2xkdzq@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* lglock: map to spinlock when !CONFIG_SMPJosh Triplett2014-04-071-1/+2
| | | | | | | | | | | | | | | | | | | When the system has only one CPU, lglock is effectively a spinlock; map it directly to spinlock to eliminate the indirection and duplicate code. In addition to removing overhead, this drops 1.6k of code with a defconfig modified to have !CONFIG_SMP, and 1.1k with a minimal config. Signed-off-by: Josh Triplett <josh@joshtriplett.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Michal Marek <mmarek@suse.cz> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: David Howells <dhowells@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Nick Piggin <npiggin@kernel.dk> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge branch 'core-rcu-for-linus' of ↵Linus Torvalds2014-03-311-0/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull RCU updates from Ingo Molnar: "Main changes: - Torture-test changes, including refactoring of rcutorture and introduction of a vestigial locktorture. - Real-time latency fixes. - Documentation updates. - Miscellaneous fixes" * 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (77 commits) rcu: Provide grace-period piggybacking API rcu: Ensure kernel/rcu/rcu.h can be sourced/used stand-alone rcu: Fix sparse warning for rcu_expedited from kernel/ksysfs.c notifier: Substitute rcu_access_pointer() for rcu_dereference_raw() Documentation/memory-barriers.txt: Clarify release/acquire ordering rcutorture: Save kvm.sh output to log rcutorture: Add a lock_busted to test the test rcutorture: Place kvm-test-1-run.sh output into res directory rcutorture: Rename TREE_RCU-Kconfig.txt locktorture: Add kvm-recheck.sh plug-in for locktorture rcutorture: Gracefully handle NULL cleanup hooks locktorture: Add vestigial locktorture configuration rcutorture: Introduce "rcu" directory level underneath configs rcutorture: Rename kvm-test-1-rcu.sh rcutorture: Remove RCU dependencies from ver_functions.sh API rcutorture: Create CFcommon file for common Kconfig parameters rcutorture: Create config files for scripted test-the-test testing rcutorture: Add an rcu_busted to test the test locktorture: Add a lock-torture kernel module rcutorture: Abstract kvm-recheck.sh ...
| * locktorture: Add a lock-torture kernel modulePaul E. McKenney2014-02-231-0/+1
| | | | | | | | | | | | | | | | | | This commit adds the locking counterpart to rcutorture. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> [ paulmck: Make n_lock_torture_errors and torture_spinlock static as suggested by Fengguang Wu. ] Reviewed-by: Josh Triplett <josh@joshtriplett.org>
* | locking/mutexes: Introduce cancelable MCS lock for adaptive spinningPeter Zijlstra2014-03-111-1/+1
|/ | | | | | | | | | | | | | | | | | | | | | | | | Since we want a task waiting for a mutex_lock() to go to sleep and reschedule on need_resched() we must be able to abort the mcs_spin_lock() around the adaptive spin. Therefore implement a cancelable mcs lock. Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: chegu_vinod@hp.com Cc: paulmck@linux.vnet.ibm.com Cc: Waiman.Long@hp.com Cc: torvalds@linux-foundation.org Cc: tglx@linutronix.de Cc: riel@redhat.com Cc: akpm@linux-foundation.org Cc: davidlohr@hp.com Cc: hpa@zytor.com Cc: andi@firstfloor.org Cc: aswin@hp.com Cc: scott.norton@hp.com Cc: Jason Low <jason.low2@hp.com> Link: http://lkml.kernel.org/n/tip-62hcl5wxydmjzd182zhvk89m@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* locking: Move the percpu-rwsem code to kernel/locking/Peter Zijlstra2013-11-061-1/+2
| | | | | | | Suggested-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/n/tip-52bjmtty46we26hbfd9sc9iy@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* locking: Move the lglocks code to kernel/locking/Peter Zijlstra2013-11-061-1/+1
| | | | | | | Suggested-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/n/tip-amd6pg1mif6tikbyktfvby3y@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* locking: Move the rwsem code to kernel/locking/Peter Zijlstra2013-11-061-1/+3
| | | | | | | | | | Notably: changed lib/rwsem* targets from lib- to obj-, no idea about the ramifications of that. Suggested-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/n/tip-g0kynfh5feriwc6p3h6kpbw6@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* locking: Move the rtmutex code to kernel/locking/Peter Zijlstra2013-11-061-0/+3
| | | | | | | | Suggested-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/n/tip-p9ijt8div0hwldexwfm4nlhj@git.kernel.org [ Fixed build failure in kernel/rcu/tree_plugin.h. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
* locking: Move the semaphore core to kernel/locking/Peter Zijlstra2013-11-061-1/+1
| | | | | | | Suggested-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/n/tip-vmw5sf6vzmua1z6nx1cg69h2@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* locking: Move the spinlock code to kernel/locking/Peter Zijlstra2013-11-061-0/+4
| | | | | | | Suggested-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/n/tip-b81ol0z3mon45m51o131yc9j@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* locking: Move the lockdep code to kernel/locking/Peter Zijlstra2013-11-061-0/+6
| | | | | | | Suggested-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/n/tip-wl7s3tta5isufzfguc23et06@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* locking: Move the mutex code to kernel/locking/Peter Zijlstra2013-11-061-0/+9
Suggested-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/n/tip-1ditvncg30dgbpvrz2bxfmke@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
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