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2018-08-09signal: Don't restart fork when signals come in.Eric W. Biederman1-0/+1
Wen Yang <wen.yang99@zte.com.cn> and majiang <ma.jiang@zte.com.cn> report that a periodic signal received during fork can cause fork to continually restart preventing an application from making progress. The code was being overly pessimistic. Fork needs to guarantee that a signal sent to multiple processes is logically delivered before the fork and just to the forking process or logically delivered after the fork to both the forking process and it's newly spawned child. For signals like periodic timers that are always delivered to a single process fork can safely complete and let them appear to logically delivered after the fork(). While examining this issue I also discovered that fork today will miss signals delivered to multiple processes during the fork and handled by another thread. Similarly the current code will also miss blocked signals that are delivered to multiple process, as those signals will not appear pending during fork. Add a list of each thread that is currently forking, and keep on that list a signal set that records all of the signals sent to multiple processes. When fork completes initialize the new processes shared_pending signal set with it. The calculate_sigpending function will see those signals and set TIF_SIGPENDING causing the new task to take the slow path to userspace to handle those signals. Making it appear as if those signals were received immediately after the fork. It is not possible to send real time signals to multiple processes and exceptions don't go to multiple processes, which means that that are no signals sent to multiple processes that require siginfo. This means it is safe to not bother collecting siginfo on signals sent during fork. The sigaction of a child of fork is initially the same as the sigaction of the parent process. So a signal the parent ignores the child will also initially ignore. Therefore it is safe to ignore signals sent to multiple processes and ignored by the forking process. Signals sent to only a single process or only a single thread and delivered during fork are treated as if they are received after the fork, and generally not dealt with. They won't cause any problems. V2: Added removal from the multiprocess list on failure. V3: Use -ERESTARTNOINTR directly V4: - Don't queue both SIGCONT and SIGSTOP - Initialize signal_struct.multiprocess in init_task - Move setting of shared_pending to before the new task is visible to signals. This prevents signals from comming in before shared_pending.signal is set to delayed.signal and being lost. V5: - rework list add and delete to account for idle threads v6: - Use sigdelsetmask when removing stop signals Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=200447 Reported-by: Wen Yang <wen.yang99@zte.com.cn> and Reported-by: majiang <ma.jiang@zte.com.cn> Fixes: 4a2c7a7837da ("[PATCH] make fork() atomic wrt pgrp/session signals") Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2018-07-21pid: Implement PIDTYPE_TGIDEric W. Biederman1-1/+1
Everywhere except in the pid array we distinguish between a tasks pid and a tasks tgid (thread group id). Even in the enumeration we want that distinction sometimes so we have added __PIDTYPE_TGID. With leader_pid we almost have an implementation of PIDTYPE_TGID in struct signal_struct. Add PIDTYPE_TGID as a first class member of the pid_type enumeration and into the pids array. Then remove the __PIDTYPE_TGID special case and the leader_pid in signal_struct. The net size increase is just an extra pointer added to struct pid and an extra pair of pointers of an hlist_node added to task_struct. The effect on code maintenance is the removal of a number of special cases today and the potential to remove many more special cases as PIDTYPE_TGID gets used to it's fullest. The long term potential is allowing zombie thread group leaders to exit, which will remove a lot more special cases in the code. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2018-07-21pids: Move the pgrp and session pid pointers from task_struct to signal_structEric W. Biederman1-5/+6
To access these fields the code always has to go to group leader so going to signal struct is no loss and is actually a fundamental simplification. This saves a little bit of memory by only allocating the pid pointer array once instead of once for every thread, and even better this removes a few potential races caused by the fact that group_leader can be changed by de_thread, while signal_struct can not. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2018-07-21pids: Initialize leader_pid in init_taskEric W. Biederman1-0/+1
This is cheap and no cost so we might as well. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2018-05-14audit: convert sessionid unset to a macroRichard Guy Briggs1-1/+2
Use a macro, "AUDIT_SID_UNSET", to replace each instance of initialization and comparison to an audit session ID. Signed-off-by: Richard Guy Briggs <rgb@redhat.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
2018-01-17Expand the INIT_SIGNALS and INIT_SIGHAND macros and removeDavid Howells1-2/+28
There doesn't seem to be any need to have the INIT_SIGNALS and INIT_SIGHAND macros, so expand them in their single places of use and remove them. Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: Tony Luck <tony.luck@intel.com> Tested-by: Will Deacon <will.deacon@arm.com> (arm64) Tested-by: Palmer Dabbelt <palmer@sifive.com> Acked-by: Thomas Gleixner <tglx@linutronix.de>
2018-01-17Expand various INIT_* macros and removeDavid Howells1-24/+71
Expand various INIT_* macros into the single places they're used in init/init_task.c and remove them. Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: Tony Luck <tony.luck@intel.com> Tested-by: Will Deacon <will.deacon@arm.com> (arm64) Tested-by: Palmer Dabbelt <palmer@sifive.com> Acked-by: Thomas Gleixner <tglx@linutronix.de>
2018-01-17Expand INIT_TASK() in init/init_task.c and removeDavid Howells1-2/+83
It's no longer necessary to have an INIT_TASK() macro, and this can be expanded into the one place it is now used and removed. Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: Tony Luck <tony.luck@intel.com> Tested-by: Will Deacon <will.deacon@arm.com> (arm64) Tested-by: Palmer Dabbelt <palmer@sifive.com> Acked-by: Thomas Gleixner <tglx@linutronix.de>
2018-01-09Construct init thread stack in the linker script rather than by unionDavid Howells1-4/+6
Construct the init thread stack in the linker script rather than doing it by means of a union so that ia64's init_task.c can be got rid of. The following symbols are then made available from INIT_TASK_DATA() linker script macro: init_thread_union init_stack INIT_TASK_DATA() also expands the region to THREAD_SIZE to accommodate the size of the init stack. init_thread_union is given its own section so that it can be placed into the stack space in the right order. I'm assuming that the ia64 ordering is correct and that the task_struct is first and the thread_info second. Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: Tony Luck <tony.luck@intel.com> Tested-by: Will Deacon <will.deacon@arm.com> (arm64) Tested-by: Palmer Dabbelt <palmer@sifive.com> Acked-by: Thomas Gleixner <tglx@linutronix.de>
2017-11-02License cleanup: add SPDX GPL-2.0 license identifier to files with no licenseGreg Kroah-Hartman1-0/+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>
2017-03-02sched/headers: Prepare to move 'init_task' and 'init_thread_union' from ↵Ingo Molnar1-0/+1
<linux/sched.h> to <linux/sched/task.h> Update all usage sites first. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> 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>
2016-12-24Replace <asm/uaccess.h> with <linux/uaccess.h> globallyLinus Torvalds1-1/+1
This was entirely automated, using the script by Al: PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*<asm/uaccess.h>' sed -i -e "s!$PATT!#include <linux/uaccess.h>!" \ $(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h) to do the replacement at the end of the merge window. Requested-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-09-15sched/core: Allow putting thread_info into task_structAndy Lutomirski1-2/+5
If an arch opts in by setting CONFIG_THREAD_INFO_IN_TASK_STRUCT, then thread_info is defined as a single 'u32 flags' and is the first entry of task_struct. thread_info::task is removed (it serves no purpose if thread_info is embedded in task_struct), and thread_info::cpu gets its own slot in task_struct. This is heavily based on a patch written by Linus. Originally-from: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Jann Horn <jann@thejh.net> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/a0898196f0476195ca02713691a5037a14f2aac5.1473801993.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-02-07sched/rt: Move rt specific bits into new header fileClark Williams1-0/+1
Move rt scheduler definitions out of include/linux/sched.h into new file include/linux/sched/rt.h Signed-off-by: Clark Williams <williams@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/20130207094707.7b9f825f@riff.lan Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-02-07sched: Move sched.h sysctl bits into separate headerClark Williams1-0/+1
Move the sysctl-related bits from include/linux/sched.h into a new file: include/linux/sched/sysctl.h. Then update source files requiring access to those bits by including the new header file. Signed-off-by: Clark Williams <williams@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/20130207094659.06dced96@riff.lan Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-05-05init_task: Create generic init_task instanceThomas Gleixner1-0/+24
All archs define init_task in the same way (except ia64, but there is no particular reason why ia64 cannot use the common version). Create a generic instance so all archs can be converted over. The config switch is temporary and will be removed when all archs are converted over. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Chen Liqin <liqin.chen@sunplusct.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Chris Zankel <chris@zankel.net> Cc: David Howells <dhowells@redhat.com> Cc: David S. Miller <davem@davemloft.net> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Guan Xuetao <gxt@mprc.pku.edu.cn> Cc: Haavard Skinnemoen <hskinnemoen@gmail.com> Cc: Hirokazu Takata <takata@linux-m32r.org> Cc: James E.J. Bottomley <jejb@parisc-linux.org> Cc: Jesper Nilsson <jesper.nilsson@axis.com> Cc: Jonas Bonn <jonas@southpole.se> Cc: Mark Salter <msalter@redhat.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Matt Turner <mattst88@gmail.com> Cc: Michal Simek <monstr@monstr.eu> Cc: Mike Frysinger <vapier@gentoo.org> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Richard Kuo <rkuo@codeaurora.org> Cc: Richard Weinberger <richard@nod.at> Cc: Russell King <linux@arm.linux.org.uk> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Link: http://lkml.kernel.org/r/20120503085034.092585287@linutronix.de