kernel.git/include/trace/events/rcu.h, branch linux-4.16.y

Merge branches 'cond_resched.2017.12.04a', 'dyntick.2017.11.28a', 'fixes.2017.12.11a', 'srbd.2017.12.05a' and 'torture.2017.12.11a' into HEAD

2017-12-11T17:21:58Z

cond_resched.2017.12.04a: Convert cond_resched_rcu_qs() to cond_resched() dyntick.2017.11.28a: Make RCU dynticks handle interrupts from NMI fixes.2017.12.11a: Miscellaneous fixes srbd.2017.12.05a: Remove now-redundant smp_read_barrier_depends() torture.2017.12.11a: Torture-testing update

tracing, rcu: Hide trace event rcu_nocb_wake when not used

2017-12-11T17:17:39Z

The trace event rcu_nocb_wake is only used when CONFIG_RCU_NOCB_CPU is defined. But the trace event is defined regardless. As defined trace events take up memory, it is a waste to have it defined when not used. Surround the trace event with an #ifdef to have it only defined when it is used. Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Paul E. McKenney

tracing, rcu: Remove no longer used trace event rcu_prep_idle

2017-11-28T23:51:22Z

Commit c0f4dfd4f90 ("rcu: Make RCU_FAST_NO_HZ take advantage of numbered callbacks") removed the only instances of trace_rcu_prep_idle, but did not remove the TRACE_EVENT() that creates it. As defined trace events take up memory within the kernel even when they are not used, this is a waste of space. Remove the obsolete event. Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Paul E. McKenney

rcu: Simplify rcu_eqs_{enter,exit}() non-idle task debug code

2017-11-28T23:51:21Z

The code that checks for non-idle non-nohz_idle-usermode tasks invoking rcu_eqs_enter() and rcu_eqs_exit() prints a considerable quantity of helpful information. However, these checks fire rarely, so the extra complexity is no longer worth it. This commit therefore replaces this debug code with simple WARN_ON_ONCE() statements. Signed-off-by: Paul E. McKenney

rcu: Add ->dynticks field to rcu_dyntick trace event

2017-11-28T23:51:19Z

Signed-off-by: Paul E. McKenney

rcu: Shrink ->dynticks_{nmi_,}nesting from long long to long

2017-11-28T23:51:18Z

Because the ->dynticks_nesting field now only contains the process-based nesting level instead of a value encoding both the process nesting level and the irq "nesting" level, we no longer need a long long, even on 32-bit systems. This commit therefore changes both the ->dynticks_nesting and ->dynticks_nmi_nesting fields to long. Signed-off-by: Paul E. McKenney

rcu: Add tracing to irq/NMI dyntick-idle transitions

2017-11-28T23:51:18Z

Signed-off-by: Paul E. McKenney

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

2017-11-02T10:10:55Z

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

rcutorture: Place event-traced strings into trace buffer

2017-07-24T23:04:12Z

Strings used in event tracing need to be specially handled, for example, being copied to the trace buffer instead of being pointed to by the trace buffer. Although the TPS() macro can be used to "launder" pointed-to strings, this might not be all that effective within a loadable module. This commit therefore copies rcutorture's strings to the trace buffer. Signed-off-by: Paul E. McKenney Cc: Steven Rostedt

rcu: Prevent rcu_barrier() from starting needless grace periods

2017-06-08T15:25:22Z

Currently rcu_barrier() uses call_rcu() to enqueue new callbacks on each CPU with a non-empty callback list. This works, but means that rcu_barrier() forces grace periods that are not otherwise needed. The key point is that rcu_barrier() never needs to wait for a grace period, but instead only for all pre-existing callbacks to be invoked. This means that rcu_barrier()'s new callbacks should be placed in the callback-list segment containing the last pre-existing callback. This commit makes this change using the new rcu_segcblist_entrain() function. Signed-off-by: Paul E. McKenney