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* list: introduce list_bulk_move_tail helperChristian König2018-10-101-0/+23
| | | | | | | | | | | | | | | Move all entries between @first and including @last before @head. This is useful for LRU lists where a whole block of entries should be moved to the end of the list. Used as a band aid in TTM, but better placed in the common list headers. Acked-by: Dave Airlie <airlied@redhat.com> Signed-off-by: Christian König <christian.koenig@amd.com> Reviewed-by: Huang Rui <ray.huang@amd.com> Reviewed-by: Junwei Zhang <Jerry.Zhang@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
* net: core: another layer of lists, around PF_MEMALLOC skb handlingEdward Cree2018-07-041-0/+30
| | | | | | | | | | First example of a layer splitting the list (rather than merely taking individual packets off it). Involves new list.h function, list_cut_before(), like list_cut_position() but cuts on the other side of the given entry. Signed-off-by: Edward Cree <ecree@solarflare.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* 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>
* list: introduce list_for_each_entry_from_reverse helperJiri Pirko2017-02-031-0/+13
| | | | | | | | | | Similar to list_for_each_entry_continue and its reverse variant list_for_each_entry_continue_reverse, introduce reverse helper for list_for_each_entry_from. Signed-off-by: Jiri Pirko <jiri@mellanox.com> Acked-by: Ido Schimmel <idosch@mellanox.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* list: Split list_del() debug checking into separate functionKees Cook2016-10-311-6/+9
| | | | | | | | | | | | | | Similar to the list_add() debug consolidation, this commit consolidates the debug checking performed during CONFIG_DEBUG_LIST into a new __list_del_entry_valid() function, and stops list updates when corruption is found. Refactored from same hardening in PaX and Grsecurity. Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com>
* list: Split list_add() debug checking into separate functionKees Cook2016-10-311-6/+16
| | | | | | | | | | | | | | | | | Right now, __list_add() code is repeated either in list.h or in list_debug.c, but the only differences between the two versions are the debug checks. This commit therefore extracts these debug checks into a separate __list_add_valid() function and consolidates __list_add(). Additionally this new __list_add_valid() function will stop list manipulations if a corruption is detected, instead of allowing for further corruption that may lead to even worse conditions. This is slight refactoring of the same hardening done in PaX and Grsecurity. Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com>
* list: Expand list_first_entry_or_null()Chris Wilson2016-09-141-2/+5
| | | | | | | | | | | | | | | | | Due to the use of READ_ONCE() in list_empty() the compiler cannot optimise !list_empty() ? list_first_entry() : NULL very well. By manually expanding list_first_entry_or_null() we can take advantage of the READ_ONCE() to avoid the list element changing under the test while the compiler can generate smaller code. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Josef Bacik <jbacik@fb.com> Cc: linux-kernel@vger.kernel.org Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* hlist: Add hlist_is_singular_node() helperThomas Gleixner2016-07-071-0/+10
| | | | | | | | | | | | | | | | | | | | Required to figure out whether the entry is the only one in the hlist. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Arjan van de Ven <arjan@infradead.org> Cc: Chris Mason <clm@fb.com> Cc: Eric Dumazet <edumazet@google.com> Cc: George Spelvin <linux@sciencehorizons.net> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Len Brown <lenb@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160704094341.867631372@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
* list: kill list_force_poison()Dan Williams2016-03-091-11/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Given we have uninitialized list_heads being passed to list_add() it will always be the case that those uninitialized values randomly trigger the poison value. Especially since a list_add() operation will seed the stack with the poison value for later stack allocations to trip over. For example, see these two false positive reports: list_add attempted on force-poisoned entry WARNING: at lib/list_debug.c:34 [..] NIP [c00000000043c390] __list_add+0xb0/0x150 LR [c00000000043c38c] __list_add+0xac/0x150 Call Trace: __list_add+0xac/0x150 (unreliable) __down+0x4c/0xf8 down+0x68/0x70 xfs_buf_lock+0x4c/0x150 [xfs] list_add attempted on force-poisoned entry(0000000000000500), new->next == d0000000059ecdb0, new->prev == 0000000000000500 WARNING: at lib/list_debug.c:33 [..] NIP [c00000000042db78] __list_add+0xa8/0x140 LR [c00000000042db74] __list_add+0xa4/0x140 Call Trace: __list_add+0xa4/0x140 (unreliable) rwsem_down_read_failed+0x6c/0x1a0 down_read+0x58/0x60 xfs_log_commit_cil+0x7c/0x600 [xfs] Fixes: commit 5c2c2587b132 ("mm, dax, pmem: introduce {get|put}_dev_pagemap() for dax-gup") Signed-off-by: Dan Williams <dan.j.williams@intel.com> Reported-by: Eryu Guan <eguan@redhat.com> Tested-by: Eryu Guan <eguan@redhat.com> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, dax, pmem: introduce {get|put}_dev_pagemap() for dax-gupDan Williams2016-01-151-0/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | get_dev_page() enables paths like get_user_pages() to pin a dynamically mapped pfn-range (devm_memremap_pages()) while the resulting struct page objects are in use. Unlike get_page() it may fail if the device is, or is in the process of being, disabled. While the initial lookup of the range may be an expensive list walk, the result is cached to speed up subsequent lookups which are likely to be in the same mapped range. devm_memremap_pages() now requires a reference counter to be specified at init time. For pmem this means moving request_queue allocation into pmem_alloc() so the existing queue usage counter can track "device pages". ZONE_DEVICE pages always have an elevated count and will never be on an lru reclaim list. That space in 'struct page' can be redirected for other uses, but for safety introduce a poison value that will always trip __list_add() to assert. This allows half of the struct list_head storage to be reclaimed with some assurance to back up the assumption that the page count never goes to zero and a list_add() is never attempted. Signed-off-by: Dan Williams <dan.j.williams@intel.com> Tested-by: Logan Gunthorpe <logang@deltatee.com> Cc: Dave Hansen <dave@sr71.net> Cc: Matthew Wilcox <willy@linux.intel.com> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* list: Use WRITE_ONCE() when initializing list_head structuresPaul E. McKenney2015-12-041-1/+1
| | | | | | | | | | | Code that does lockless emptiness testing of non-RCU lists is relying on INIT_LIST_HEAD() to write the list head's ->next pointer atomically, particularly when INIT_LIST_HEAD() is invoked from list_del_init(). This commit therefore adds WRITE_ONCE() to this function's pointer stores that could affect the head's ->next pointer. Reported-by: Andrey Konovalov <andreyknvl@google.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* list: Use READ_ONCE() when testing for empty listsPaul E. McKenney2015-11-231-2/+2
| | | | | | | | | | | | | Most of the list-empty-check macros (list_empty(), hlist_empty(), hlist_bl_empty(), hlist_nulls_empty(), and hlist_nulls_empty()) use an unadorned load to check the list header. Given that these macros are sometimes invoked without the protection of a lock, this is not sufficient. This commit therefore adds READ_ONCE() calls to them. This commit does not touch llist_empty() because it already has the needed ACCESS_ONCE(). Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* list: Use WRITE_ONCE() when adding to lists and hlistsPaul E. McKenney2015-11-231-4/+4
| | | | | | | | | | Code that does lockless emptiness testing of non-RCU lists is relying on the list-addition code to write the list head's ->next pointer atomically. This commit therefore adds WRITE_ONCE() to list-addition pointer stores that could affect the head's ->next pointer. Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* rculist: Use WRITE_ONCE() when deleting from reader-visible listPaul E. McKenney2015-10-061-2/+3
| | | | | | | | | | | | | | | | | | The various RCU list-deletion macros (list_del_rcu(), hlist_del_init_rcu(), hlist_del_rcu(), hlist_bl_del_init_rcu(), hlist_bl_del_rcu(), hlist_nulls_del_init_rcu(), and hlist_nulls_del_rcu()) do plain stores into the ->next pointer of the preceding list elemment. Unfortunately, the compiler is within its rights to (for example) use byte-at-a-time writes to update the pointer, which would fatally confuse concurrent readers. This patch therefore adds the needed WRITE_ONCE() macros. KernelThreadSanitizer (KTSAN) reported the __hlist_del() issue, which is a problem when __hlist_del() is invoked by hlist_del_rcu(). Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
* inode: add hlist_fake to avoid the inode hash lock in evictJosef Bacik2015-08-171-0/+5
| | | | | | | | | | | | | | | | | | | | | | Some filesystems don't use the VFS inode hash and fake the fact they are hashed so that all the writeback code works correctly. However, this means the evict() path still tries to remove the inode from the hash, meaning that the inode_hash_lock() needs to be taken unnecessarily. Hence under certain workloads the inode_hash_lock can be contended even if the inode is never actually hashed. To avoid this add hlist_fake to test if the inode isn't actually hashed to avoid taking the hash lock on inodes that have never been hashed. Based on Dave Chinner's inode: add IOP_NOTHASHED to avoid inode hash lock in evict basd on Al's suggestions. Thanks, Signed-off-by: Josef Bacik <jbacik@fb.com> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Christoph Hellwig <hch@lst.de> Tested-by: Dave Chinner <dchinner@redhat.com>
* Replace mentions of "list_struct" to "list_head"Andrey Utkin2014-11-201-17/+17
| | | | | | | | | | | There's no such thing as "list_struct". Signed-off-by: Andrey Utkin <andrey.krieger.utkin@gmail.com> Acked-by: Steven Rostedt <rostedt@goodmis.org> Acked-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Alex Deucher <alexander.deucher@amd.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
* list: include linux/kernel.hMasahiro Yamada2014-10-141-0/+1
| | | | | | | | linux/list.h uses container_of, therefore it depends on linux/kernel.h. Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* list: fix order of arguments for hlist_add_after(_rcu)Ken Helias2014-08-061-2/+2
| | | | | | | | | | | | | | | | | | | All other add functions for lists have the new item as first argument and the position where it is added as second argument. This was changed for no good reason in this function and makes using it unnecessary confusing. The name was changed to hlist_add_behind() to cause unconverted code to generate a compile error instead of using the wrong parameter order. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Ken Helias <kenhelias@firemail.de> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Acked-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com> [intel driver bits] Cc: Hugh Dickins <hughd@google.com> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* list: make hlist_add_after() argument names match hlist_add_after_rcu()Ken Helias2014-08-061-7/+7
| | | | | | | | | | | | | | | | The argument names for hlist_add_after() are poorly chosen because they look the same as the ones for hlist_add_before() but have to be used differently. hlist_add_after_rcu() has made a better choice. Signed-off-by: Ken Helias <kenhelias@firemail.de> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Hugh Dickins <hughd@google.com> Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* list: introduce list_last_entry(), use list_{first,last}_entry()Oleg Nesterov2013-11-131-4/+15
| | | | | | | | | | | | | We already have list_first_entry(), it makes sense to also add list_last_entry() for consistency. And we use both helpers in list_for_each_*(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Eilon Greenstein <eilong@broadcom.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 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>
* list: change list_for_each_entry*() to use list_*_entry()Oleg Nesterov2013-11-131-22/+22
| | | | | | | | | | | | | Now that we have list_{next,prev}_entry() we can change list_for_each_entry*() and list_safe_reset_next() to use the new helpers to improve the readability. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Eilon Greenstein <eilong@broadcom.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 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>
* list: introduce list_next_entry() and list_prev_entry()Oleg Nesterov2013-11-131-0/+16
| | | | | | | | | | | | | | Add two trivial helpers list_next_entry() and list_prev_entry(), they can have a lot of users including list.h itself. In fact the 1st one is already defined in events/core.c and bnx2x_sp.c, so the patch simply moves the definition to list.h. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Eilon Greenstein <eilong@broadcom.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 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>
* linked-list: Remove __list_for_eachDave Jones2013-07-161-11/+0
| | | | | | | | | | | | | | __list_for_each used to be the non prefetch() aware list walking primitive. When we removed the prefetch macros from the list routines, it became redundant. Given it does exactly the same thing as list_for_each now, we might as well remove it and call list_for_each directly. All users of __list_for_each have been converted to list_for_each calls in the current merge window. Signed-off-by: Dave Jones <davej@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* list: introduce list_first_entry_or_nullJiri Pirko2013-05-311-0/+11
| | | | | | | non-rcu variant of list_first_or_null_rcu Signed-off-by: Jiri Pirko <jiri@resnulli.us> Signed-off-by: David S. Miller <davem@davemloft.net>
* list: Fix double fetch of pointer in hlist_entry_safe()Paul E. McKenney2013-03-141-1/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The current version of hlist_entry_safe() fetches the pointer twice, once to test for NULL and the other to compute the offset back to the enclosing structure. This is OK for normal lock-based use because in that case, the pointer cannot change. However, when the pointer is protected by RCU (as in "rcu_dereference(p)"), then the pointer can change at any time. This use case can result in the following sequence of events: 1. CPU 0 invokes hlist_entry_safe(), fetches the RCU-protected pointer as sees that it is non-NULL. 2. CPU 1 invokes hlist_del_rcu(), deleting the entry that CPU 0 just fetched a pointer to. Because this is the last entry in the list, the pointer fetched by CPU 0 is now NULL. 3. CPU 0 refetches the pointer, obtains NULL, and then gets a NULL-pointer crash. This commit therefore applies gcc's "({ })" statement expression to create a temporary variable so that the specified pointer is fetched only once, avoiding the above sequence of events. Please note that it is the caller's responsibility to use rcu_dereference() as needed. This allows RCU-protected uses to work correctly without imposing any additional overhead on the non-RCU case. Many thanks to Eric Dumazet for spotting root cause! Reported-by: CAI Qian <caiqian@redhat.com> Reported-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Tested-by: Li Zefan <lizefan@huawei.com>
* hlist: drop the node parameter from iteratorsSasha Levin2013-02-271-27/+22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | I'm not sure why, but the hlist for each entry iterators were conceived list_for_each_entry(pos, head, member) The hlist ones were greedy and wanted an extra parameter: hlist_for_each_entry(tpos, pos, head, member) Why did they need an extra pos parameter? I'm not quite sure. Not only they don't really need it, it also prevents the iterator from looking exactly like the list iterator, which is unfortunate. Besides the semantic patch, there was some manual work required: - Fix up the actual hlist iterators in linux/list.h - Fix up the declaration of other iterators based on the hlist ones. - A very small amount of places were using the 'node' parameter, this was modified to use 'obj->member' instead. - Coccinelle didn't handle the hlist_for_each_entry_safe iterator properly, so those had to be fixed up manually. The semantic patch which is mostly the work of Peter Senna Tschudin is here: @@ iterator name hlist_for_each_entry, hlist_for_each_entry_continue, hlist_for_each_entry_from, hlist_for_each_entry_rcu, hlist_for_each_entry_rcu_bh, hlist_for_each_entry_continue_rcu_bh, for_each_busy_worker, ax25_uid_for_each, ax25_for_each, inet_bind_bucket_for_each, sctp_for_each_hentry, sk_for_each, sk_for_each_rcu, sk_for_each_from, sk_for_each_safe, sk_for_each_bound, hlist_for_each_entry_safe, hlist_for_each_entry_continue_rcu, nr_neigh_for_each, nr_neigh_for_each_safe, nr_node_for_each, nr_node_for_each_safe, for_each_gfn_indirect_valid_sp, for_each_gfn_sp, for_each_host; type T; expression a,c,d,e; identifier b; statement S; @@ -T b; <+... when != b ( hlist_for_each_entry(a, - b, c, d) S | hlist_for_each_entry_continue(a, - b, c) S | hlist_for_each_entry_from(a, - b, c) S | hlist_for_each_entry_rcu(a, - b, c, d) S | hlist_for_each_entry_rcu_bh(a, - b, c, d) S | hlist_for_each_entry_continue_rcu_bh(a, - b, c) S | for_each_busy_worker(a, c, - b, d) S | ax25_uid_for_each(a, - b, c) S | ax25_for_each(a, - b, c) S | inet_bind_bucket_for_each(a, - b, c) S | sctp_for_each_hentry(a, - b, c) S | sk_for_each(a, - b, c) S | sk_for_each_rcu(a, - b, c) S | sk_for_each_from -(a, b) +(a) S + sk_for_each_from(a) S | sk_for_each_safe(a, - b, c, d) S | sk_for_each_bound(a, - b, c) S | hlist_for_each_entry_safe(a, - b, c, d, e) S | hlist_for_each_entry_continue_rcu(a, - b, c) S | nr_neigh_for_each(a, - b, c) S | nr_neigh_for_each_safe(a, - b, c, d) S | nr_node_for_each(a, - b, c) S | nr_node_for_each_safe(a, - b, c, d) S | - for_each_gfn_sp(a, c, d, b) S + for_each_gfn_sp(a, c, d) S | - for_each_gfn_indirect_valid_sp(a, c, d, b) S + for_each_gfn_indirect_valid_sp(a, c, d) S | for_each_host(a, - b, c) S | for_each_host_safe(a, - b, c, d) S | for_each_mesh_entry(a, - b, c, d) S ) ...+> [akpm@linux-foundation.org: drop bogus change from net/ipv4/raw.c] [akpm@linux-foundation.org: drop bogus hunk from net/ipv6/raw.c] [akpm@linux-foundation.org: checkpatch fixes] [akpm@linux-foundation.org: fix warnings] [akpm@linux-foudnation.org: redo intrusive kvm changes] Tested-by: Peter Senna Tschudin <peter.senna@gmail.com> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Gleb Natapov <gleb@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* list: remove prefetching from regular list iteratorsLinus Torvalds2011-05-191-15/+11
| | | | | | | | | | | | | | | | | | | | This is removes the use of software prefetching from the regular list iterators. We don't want it. If you do want to prefetch in some iterator of yours, go right ahead. Just don't expect the iterator to do it, since normally the downsides are bigger than the upsides. It also replaces <linux/prefetch.h> with <linux/const.h>, because the use of LIST_POISON ends up needing it. <linux/poison.h> is sadly not self-contained, and including prefetch.h just happened to hide that. Suggested by David Miller (networking has a lot of regular lists that are often empty or a single entry, and prefetching is not going to do anything but add useless instructions). Acked-by: Ingo Molnar <mingo@elte.hu> Acked-by: David S. Miller <davem@davemloft.net> Cc: linux-arch@vger.kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hlist: remove software prefetching in hlist iteratorsLinus Torvalds2011-05-191-5/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | They not only increase the code footprint, they actually make things slower rather than faster. On internationally acclaimed benchmarks ("make -j16" on an already fully built kernel source tree) the hlist prefetching slows down the build by up to 1%. (Almost all of it comes from hlist_for_each_entry_rcu() as used by avc_has_perm_noaudit(), which is very hot due to all the pathname lookups to see if there is anything to do). The cause seems to be two-fold: - on at least some Intel cores, prefetch(NULL) ends up with some microarchitectural stall due to the TLB miss that it incurs. The hlist case triggers this very commonly, since the NULL pointer is the last entry in the list. - the prefetch appears to cause more D$ activity, probably because it prefetches hash list entries that are never actually used (because we ended the search early due to a hit). Regardless, the numbers clearly say that the implicit prefetching is simply a bad idea. If some _particular_ user of the hlist iterators wants to prefetch the next list entry, they can do so themselves explicitly, rather than depend on all list iterators doing so implicitly. Acked-by: Ingo Molnar <mingo@elte.hu> Acked-by: David S. Miller <davem@davemloft.net> Cc: linux-arch@vger.kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Expand CONFIG_DEBUG_LIST to several other list operationsLinus Torvalds2011-02-181-3/+9
| | | | | | | | | | | | | | When list debugging is enabled, we aim to readably show list corruption errors, and the basic list_add/list_del operations end up having extra debugging code in them to do some basic validation of the list entries. However, "list_del_init()" and "list_move[_tail]()" ended up avoiding the debug code due to how they were written. This fixes that. So the _next_ time we have list_move() problems with stale list entries, we'll hopefully have an easier time finding them.. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* list.h: new helper - hlist_add_fake()Al Viro2010-10-251-0/+6
| | | | | | | | | | Make node look as if it was on hlist, with hlist_del() working correctly. Usable without any locking... Convert a couple of places where we want to do that to inode->i_hash. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* Drop a couple of unnecessary asm/system.h inclusionsDavid Howells2010-10-071-1/+0
| | | | | | | | | | Drop inclusions of asm/system.h from linux/hardirq.h and linux/list.h as they're no longer required and prevent the M68K arch's IRQ flag handling macros from being made into inlined functions due to circular dependencies. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Greg Ungerer <gerg@uclinux.org> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
* Merge branch 'master' into for-linusChris Metcalf2010-07-061-0/+15
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| * fs: fix superblock iteration racenpiggin@suse.de2010-06-291-0/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | list_for_each_entry_safe is not suitable to protect against concurrent modification of the list. 6754af6 introduced a race in sb walking. list_for_each_entry can use the trick of pinning the current entry in the list before we drop and retake the lock because it subsequently follows cur->next. However list_for_each_entry_safe saves n=cur->next for following before entering the loop body, so when the lock is dropped, n may be deleted. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Christoph Hellwig <hch@infradead.org> Cc: John Stultz <johnstul@us.ibm.com> Cc: Frank Mayhar <fmayhar@google.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | Move list types from <linux/list.h> to <linux/types.h>.Chris Metcalf2010-07-061-12/+1
|/ | | | | | | | | | | | | | | | This allows a list_head (or hlist_head, etc.) to be used from places that used to be impractical, in particular <asm/processor.h>, which used to cause include file recursion: <linux/list.h> includes <linux/prefetch.h>, which always includes <asm/processor.h> for the prefetch macros, as well as <asm/system.h>, which often includes <asm/processor.h> directly or indirectly. This avoids a lot of painful workaround hackery on the tile architecture, where we use a list_head in the thread_struct to chain together tasks that are activated on a particular hardwall. Signed-off-by: Chris Metcalf <cmetcalf@tilera.com> Reviewed-by: Matthew Wilcox <willy@linux.intel.com>
* lib: fix first line of kernel-doc for a few functionsBen Hutchings2010-03-061-3/+3
| | | | | | | | | The function name must be followed by a space, hypen, space, and a short description. Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* list: Introduce list_rotate_left()Frederic Weisbecker2010-01-161-0/+14
| | | | | | | | | | | | Bring a new list_rotate_left() helper that rotates a list to the left. This is useful for codes that need to round roubin elements which queue priority increases from tail to head. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
* debugobjects: fix lockdep warningVegard Nossum2008-09-011-0/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Daniel J. Blueman reported: > ======================================================= > [ INFO: possible circular locking dependency detected ] > 2.6.27-rc4-224c #1 > ------------------------------------------------------- > hald/4680 is trying to acquire lock: > (&n->list_lock){++..}, at: [<ffffffff802bfa26>] add_partial+0x26/0x80 > > but task is already holding lock: > (&obj_hash[i].lock){++..}, at: [<ffffffff8041cfdc>] > debug_object_free+0x5c/0x120 We fix it by moving the actual freeing to outside the lock (the lock now only protects the list). The pool lock is also promoted to irq-safe (suggested by Dan). It's necessary because free_pool is now called outside the irq disabled region. So we need to protect against an interrupt handler which calls debug_object_init(). [tglx@linutronix.de: added hlist_move_list helper to avoid looping through the list twice] Reported-by: Daniel J Blueman <daniel.blueman@gmail.com> Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* list.h: fix fatal kernel-doc errorRandy Dunlap2008-08-081-2/+2
| | | | | | | | | | Fix fatal multi-line kernel-doc error in list.h: function short description must be on one line. Error(linux-2.6.27-rc2-git3//include/linux/list.h:318): duplicate section name 'Description' Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* list.h: add list_cut_position()Luis R. Rodriguez2008-08-071-0/+40
| | | | | | | | This adds list_cut_position() which lets you cut a list into two lists given a pivot in the list. Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com> Signed-off-by: John W. Linville <linville@tuxdriver.com>
* list.h: Add list_splice_tail() and list_splice_tail_init()Luis R. Rodriguez2008-08-071-9/+38
| | | | | | | | | | | If you are using linked lists for queues list_splice() will not do what you would expect even if you use the elements passed reversed. We need to handle these differently. We add list_splice_tail() and list_splice_tail_init(). Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com> Signed-off-by: John W. Linville <linville@tuxdriver.com>
* lists: remove a redundant conditional definition of list_add()Robert P. J. Day2008-07-251-4/+0
| | | | | | | | | | | | Remove the conditional surrounding the definition of list_add() from list.h since, if you define CONFIG_DEBUG_LIST, the definition you will subsequently pick up from lib/list_debug.c will be absolutely identical, at which point you can remove that redundant definition from list_debug.c as well. Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca> Cc: Dave Jones <davej@codemonkey.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* rcu: split list.h and move rcu-protected lists into rculist.hFranck Bui-Huu2008-05-191-367/+0
| | | | | | | | | | | | | | | | | | | | | | Move rcu-protected lists from list.h into a new header file rculist.h. This is done because list are a very used primitive structure all over the kernel and it's currently impossible to include other header files in this list.h without creating some circular dependencies. For example, list.h implements rcu-protected list and uses rcu_dereference() without including rcupdate.h. It actually compiles because users of rcu_dereference() are macros. Others RCU functions could be used too but aren't probably because of this. Therefore this patch creates rculist.h which includes rcupdates without to many changes/troubles. Signed-off-by: Franck Bui-Huu <fbuihuu@gmail.com> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Josh Triplett <josh@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* Remove "#ifdef __KERNEL__" checks from unexported headersRobert P. J. Day2008-04-301-5/+0
| | | | | | | | | | | | Remove the "#ifdef __KERNEL__" tests from unexported header files in linux/include whose entire contents are wrapped in that preprocessor test. Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Sam Ravnborg <sam@ravnborg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* lists: add "const" qualifier to first arg of list_splice() operationsRobert P. J. Day2008-04-291-2/+3
| | | | | | | | | | Since neither the list_splice() nor __list_splice() routines modify their first argument, might as well declare them "const". [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* list.h: add list_is_singular()Masami Hiramatsu2008-04-281-0/+9
| | | | | | | | | | | | Add list_is_singular() to check a list has just one entry. list_is_singular() is useful to check whether a list_head which have been temporarily allocated for listing objects can be released or not. Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com> 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>
* Fix RCU list iterator use of 'rcu_dereference()'Linus Torvalds2008-04-211-33/+15
| | | | | | | | | | | | | | | | | | The RCU iterators used 'rcu_dereference()' on an already-fetched RCU pointer value, which defeats the whole point of the exercise. When we dereference a pointer protected by RCU, we need to make sure that we only fetch the value _once_, because if the compiler ends up re-loading it due to register pressure, the newly reloaded value could be different from the previously fetched one, and you get inconsistent results. Cleaned-up, fixed, and the pointless list_for_each_safe_rcu #define deleted by Paul Kenney. Acked-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* kernel-api docbook: fix content problemsRandy Dunlap2007-10-191-2/+1
| | | | | | | | | | | | | | | | | Fix kernel-api docbook contents problems. docproc: linux-2.6.23-git13/include/asm-x86/unaligned_32.h: No such file or directory Warning(linux-2.6.23-git13//include/linux/list.h:482): bad line: of list entry Warning(linux-2.6.23-git13//mm/filemap.c:864): No description found for parameter 'ra' Warning(linux-2.6.23-git13//block/ll_rw_blk.c:3760): No description found for parameter 'req' Warning(linux-2.6.23-git13//include/linux/input.h:1077): No description found for parameter 'private' Warning(linux-2.6.23-git13//include/linux/input.h:1077): No description found for parameter 'cdev' Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Cc: Jens Axboe <jens.axboe@oracle.com> Cc: WU Fengguang <wfg@mail.ustc.edu.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* shrink_dcache_sb speedupDenis V. Lunev2007-10-171-0/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | This patch makes shrink_dcache_sb consistent with dentry pruning policy. On the first pass we iterate over dentry unused list and prepare some dentries for removal. However, since the existing code moves evicted dentries to the beginning of the LRU it can happen that fresh dentries from other superblocks will be inserted *before* our dentries. This can result in significant slowdown of shrink_dcache_sb(). Moreover, for virtual filesystems like unionfs which can call dput() during dentries kill existing code results in O(n^2) complexity. We observed 2 minutes shrink_dcache_sb() with only 35000 dentries. To avoid this effects we propose to isolate sb dentries at the end of LRU list. Signed-off-by: Denis V. Lunev <den@openvz.org> Signed-off-by: Kirill Korotaev <dev@openvz.org> Signed-off-by: Andrey Mirkin <amirkin@openvz.org> Cc: Neil Brown <neilb@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [NETNS]: Cleanup list walking in setup_net and cleanup_netPavel Emelyanov2007-10-101-0/+14
| | | | | | | | | | | | | | | I proposed introducing a list_for_each_entry_continue_reverse macro to be used in setup_net() when unrolling the failed ->init callback. Here is the macro and some more cleanup in the setup_net() itself to remove one variable from the stack :) The same thing is for the cleanup_net() - the existing list_for_each_entry_reverse() is used. Minor, but the code looks nicer. Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Acked-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* include/linux: trivial repair whitespace damageDaniel Walker2007-05-121-4/+4
| | | | | | | Adding tabs where spaces currently are. Signed-off-by: Daniel Walker <dwalker@mvista.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>