From 22e4ebb975822833b083533035233d128b30e98f Mon Sep 17 00:00:00 2001 From: Mathieu Desnoyers Date: Fri, 28 Jul 2017 16:40:40 -0400 Subject: membarrier: Provide expedited private command Implement MEMBARRIER_CMD_PRIVATE_EXPEDITED with IPIs using cpumask built from all runqueues for which current thread's mm is the same as the thread calling sys_membarrier. It executes faster than the non-expedited variant (no blocking). It also works on NOHZ_FULL configurations. Scheduler-wise, it requires a memory barrier before and after context switching between processes (which have different mm). The memory barrier before context switch is already present. For the barrier after context switch: * Our TSO archs can do RELEASE without being a full barrier. Look at x86 spin_unlock() being a regular STORE for example. But for those archs, all atomics imply smp_mb and all of them have atomic ops in switch_mm() for mm_cpumask(), and on x86 the CR3 load acts as a full barrier. * From all weakly ordered machines, only ARM64 and PPC can do RELEASE, the rest does indeed do smp_mb(), so there the spin_unlock() is a full barrier and we're good. * ARM64 has a very heavy barrier in switch_to(), which suffices. * PPC just removed its barrier from switch_to(), but appears to be talking about adding something to switch_mm(). So add a smp_mb__after_unlock_lock() for now, until this is settled on the PPC side. Changes since v3: - Properly document the memory barriers provided by each architecture. Changes since v2: - Address comments from Peter Zijlstra, - Add smp_mb__after_unlock_lock() after finish_lock_switch() in finish_task_switch() to add the memory barrier we need after storing to rq->curr. This is much simpler than the previous approach relying on atomic_dec_and_test() in mmdrop(), which actually added a memory barrier in the common case of switching between userspace processes. - Return -EINVAL when MEMBARRIER_CMD_SHARED is used on a nohz_full kernel, rather than having the whole membarrier system call returning -ENOSYS. Indeed, CMD_PRIVATE_EXPEDITED is compatible with nohz_full. Adapt the CMD_QUERY mask accordingly. Changes since v1: - move membarrier code under kernel/sched/ because it uses the scheduler runqueue, - only add the barrier when we switch from a kernel thread. The case where we switch from a user-space thread is already handled by the atomic_dec_and_test() in mmdrop(). - add a comment to mmdrop() documenting the requirement on the implicit memory barrier. CC: Peter Zijlstra CC: Paul E. McKenney CC: Boqun Feng CC: Andrew Hunter CC: Maged Michael CC: gromer@google.com CC: Avi Kivity CC: Benjamin Herrenschmidt CC: Paul Mackerras CC: Michael Ellerman Signed-off-by: Mathieu Desnoyers Signed-off-by: Paul E. McKenney Tested-by: Dave Watson --- kernel/Makefile | 1 - 1 file changed, 1 deletion(-) (limited to 'kernel/Makefile') diff --git a/kernel/Makefile b/kernel/Makefile index 4cb8e8b23c6e..9c323a6daa46 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -108,7 +108,6 @@ obj-$(CONFIG_CRASH_DUMP) += crash_dump.o obj-$(CONFIG_JUMP_LABEL) += jump_label.o obj-$(CONFIG_CONTEXT_TRACKING) += context_tracking.o obj-$(CONFIG_TORTURE_TEST) += torture.o -obj-$(CONFIG_MEMBARRIER) += membarrier.o obj-$(CONFIG_HAS_IOMEM) += memremap.o -- cgit v1.2.3 From 235586939d7fe4833ada9e988f92af543ee6851f Mon Sep 17 00:00:00 2001 From: "Luis R. Rodriguez" Date: Fri, 8 Sep 2017 16:17:00 -0700 Subject: kmod: split out umh code into its own file Patch series "kmod: few code cleanups to split out umh code" The usermode helper has a provenance from the old usb code which first required a usermode helper. Eventually this was shoved into kmod.c and the kernel's modprobe calls was converted over eventually to share the same code. Over time the list of usermode helpers in the kernel has grown -- so kmod is just but one user of the API. This series is a simple logical cleanup which acknowledges the code evolution of the usermode helper and shoves the UMH API into its own dedicated file. This way users of the API can later just include umh.h instead of kmod.h. Note despite the diff state the first patch really is just a code shove, no functional changes are done there. I did use git format-patch -M to generate the patch, but in the end the split was not enough for git to consider it a rename hence the large diffstat. I've put this through 0-day and it gives me their machine compilation blessings with all tests as OK. This patch (of 4): There's a slew of usermode helper users and kmod is just one of them. Split out the usermode helper code into its own file to keep the logic and focus split up. This change provides no functional changes. Link: http://lkml.kernel.org/r/20170810180618.22457-2-mcgrof@kernel.org Signed-off-by: Luis R. Rodriguez Cc: Kees Cook Cc: Dmitry Torokhov Cc: Jessica Yu Cc: Rusty Russell Cc: Michal Marek Cc: Petr Mladek Cc: Miroslav Benes Cc: Josh Poimboeuf Cc: Guenter Roeck Cc: "Eric W. Biederman" Cc: Matt Redfearn Cc: Dan Carpenter Cc: Colin Ian King Cc: Daniel Mentz Cc: David Binderman Cc: Greg Kroah-Hartman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/Makefile') diff --git a/kernel/Makefile b/kernel/Makefile index 9c323a6daa46..44abbb0104b6 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -5,7 +5,7 @@ obj-y = fork.o exec_domain.o panic.o \ cpu.o exit.o softirq.o resource.o \ sysctl.o sysctl_binary.o capability.o ptrace.o user.o \ - signal.o sys.o kmod.o workqueue.o pid.o task_work.o \ + signal.o sys.o umh.o kmod.o workqueue.o pid.o task_work.o \ extable.o params.o \ kthread.o sys_ni.o nsproxy.o \ notifier.o ksysfs.o cred.o reboot.o \ -- cgit v1.2.3 From 0ce2c2029312ed78e37b56b08fa0f59ba97ef50b Mon Sep 17 00:00:00 2001 From: "Luis R. Rodriguez" Date: Fri, 8 Sep 2017 16:17:12 -0700 Subject: kmod: move #ifdef CONFIG_MODULES wrapper to Makefile The entire file is now conditionally compiled only when CONFIG_MODULES is enabled, and this this is a bool. Just move this conditional to the Makefile as its easier to read this way. Link: http://lkml.kernel.org/r/20170810180618.22457-5-mcgrof@kernel.org Signed-off-by: Luis R. Rodriguez Cc: Kees Cook Cc: Dmitry Torokhov Cc: Jessica Yu Cc: Rusty Russell Cc: Michal Marek Cc: Petr Mladek Cc: Miroslav Benes Cc: Josh Poimboeuf Cc: Guenter Roeck Cc: "Eric W. Biederman" Cc: Matt Redfearn Cc: Dan Carpenter Cc: Colin Ian King Cc: Daniel Mentz Cc: David Binderman Cc: Greg Kroah-Hartman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/Makefile | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'kernel/Makefile') diff --git a/kernel/Makefile b/kernel/Makefile index 44abbb0104b6..ed470aac53da 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -5,12 +5,13 @@ obj-y = fork.o exec_domain.o panic.o \ cpu.o exit.o softirq.o resource.o \ sysctl.o sysctl_binary.o capability.o ptrace.o user.o \ - signal.o sys.o umh.o kmod.o workqueue.o pid.o task_work.o \ + signal.o sys.o umh.o workqueue.o pid.o task_work.o \ extable.o params.o \ kthread.o sys_ni.o nsproxy.o \ notifier.o ksysfs.o cred.o reboot.o \ async.o range.o smpboot.o ucount.o +obj-$(CONFIG_MODULES) += kmod.o obj-$(CONFIG_MULTIUSER) += groups.o ifdef CONFIG_FUNCTION_TRACER -- cgit v1.2.3 From b24413180f5600bcb3bb70fbed5cf186b60864bd Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Wed, 1 Nov 2017 15:07:57 +0100 Subject: License cleanup: add SPDX GPL-2.0 license identifier to files with no license 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 Reviewed-by: Philippe Ombredanne Reviewed-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman --- kernel/Makefile | 1 + 1 file changed, 1 insertion(+) (limited to 'kernel/Makefile') diff --git a/kernel/Makefile b/kernel/Makefile index ed470aac53da..172d151d429c 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -1,3 +1,4 @@ +# SPDX-License-Identifier: GPL-2.0 # # Makefile for the linux kernel. # -- cgit v1.2.3