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Commit Graph

68 Commits

Author SHA1 Message Date
Thomas Gleixner
15dba1e37b hlist: Add hlist_is_singular_node() helper
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>
2016-07-07 10:35:07 +02:00
Dan Williams
d77a117e68 list: kill list_force_poison()
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 5c2c2587b1 ("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>
2016-03-09 15:43:42 -08:00
Dan Williams
5c2c2587b1 mm, dax, pmem: introduce {get|put}_dev_pagemap() for dax-gup
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>
2016-01-15 17:56:32 -08:00
Paul E. McKenney
2f073848c3 list: Use WRITE_ONCE() when initializing list_head structures
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>
2015-12-04 12:34:33 -08:00
Paul E. McKenney
1658d35ead list: Use READ_ONCE() when testing for empty lists
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>
2015-11-23 10:37:35 -08:00
Paul E. McKenney
1c97be677f list: Use WRITE_ONCE() when adding to lists and hlists
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>
2015-11-23 10:37:35 -08:00
Paul E. McKenney
7f5f873c6a rculist: Use WRITE_ONCE() when deleting from reader-visible list
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>
2015-10-06 11:16:42 -07:00
Josef Bacik
cbedaac634 inode: add hlist_fake to avoid the inode hash lock in evict
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>
2015-08-17 18:39:45 -04:00
Andrey Utkin
3943f42c11 Replace mentions of "list_struct" to "list_head"
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>
2014-11-20 14:45:15 +01:00
Masahiro Yamada
8b21d9ca17 list: include linux/kernel.h
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>
2014-10-14 02:18:13 +02:00
Ken Helias
1d023284c3 list: fix order of arguments for hlist_add_after(_rcu)
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>
2014-08-06 18:01:24 -07:00
Ken Helias
bc18dd335a list: make hlist_add_after() argument names match hlist_add_after_rcu()
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>
2014-08-06 18:01:24 -07:00
Oleg Nesterov
93be3c2eb3 list: introduce list_last_entry(), use list_{first,last}_entry()
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>
2013-11-13 12:09:24 +09:00
Oleg Nesterov
8120e2e514 list: change list_for_each_entry*() to use list_*_entry()
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>
2013-11-13 12:09:23 +09:00
Oleg Nesterov
008208c6b2 list: introduce list_next_entry() and list_prev_entry()
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>
2013-11-13 12:09:23 +09:00
Dave Jones
c0d15cc7ee linked-list: Remove __list_for_each
__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>
2013-07-16 22:00:14 -07:00
Jiri Pirko
6d7581e62f list: introduce list_first_entry_or_null
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>
2013-05-31 17:31:52 -07:00
Paul E. McKenney
f65846a180 list: Fix double fetch of pointer in hlist_entry_safe()
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>
2013-03-14 13:18:30 -07:00
Sasha Levin
b67bfe0d42 hlist: drop the node parameter from iterators
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>
2013-02-27 19:10:24 -08:00
Linus Torvalds
e66eed651f list: remove prefetching from regular list iterators
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>
2011-05-19 14:15:29 -07:00
Linus Torvalds
75d65a425c hlist: remove software prefetching in hlist iterators
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>
2011-05-19 13:50:07 -07:00
Linus Torvalds
3c18d4de86 Expand CONFIG_DEBUG_LIST to several other list operations
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>
2011-02-18 11:32:28 -08:00
Al Viro
756acc2d61 list.h: new helper - hlist_add_fake()
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>
2010-10-25 21:24:15 -04:00
David Howells
bcdb714c88 Drop a couple of unnecessary asm/system.h inclusions
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>
2010-10-07 14:08:53 +01:00
Chris Metcalf
a2262d8a23 Merge branch 'master' into for-linus 2010-07-06 13:45:24 -04:00
Chris Metcalf
de5d9bf654 Move list types from <linux/list.h> to <linux/types.h>.
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>
2010-07-06 13:33:54 -04:00
npiggin@suse.de
57439f878a fs: fix superblock iteration race
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>
2010-06-29 10:38:22 -07:00
Ben Hutchings
9a86e2bad0 lib: fix first line of kernel-doc for a few functions
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>
2010-03-06 11:26:35 -08:00
Frederic Weisbecker
5908cdc85e list: Introduce list_rotate_left()
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>
2010-01-16 12:29:32 +01:00
Vegard Nossum
673d62cc5e debugobjects: fix lockdep warning
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>
2008-09-01 09:47:16 +02:00
Randy Dunlap
6724cce8fb list.h: fix fatal kernel-doc error
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>
2008-08-08 16:17:16 -07:00
Luis R. Rodriguez
00e8a4da8c list.h: add list_cut_position()
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>
2008-08-07 09:49:42 -04:00
Luis R. Rodriguez
7d283aee50 list.h: Add list_splice_tail() and list_splice_tail_init()
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>
2008-08-07 09:49:42 -04:00
Robert P. J. Day
e0ce0da9fe lists: remove a redundant conditional definition of list_add()
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>
2008-07-25 10:53:27 -07:00
Franck Bui-Huu
82524746c2 rcu: split list.h and move rcu-protected lists into rculist.h
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>
2008-05-19 10:01:37 +02:00
Robert P. J. Day
735643ee6c Remove "#ifdef __KERNEL__" checks from unexported headers
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>
2008-04-30 08:29:54 -07:00
Robert P. J. Day
95d8c365b2 lists: add "const" qualifier to first arg of list_splice() operations
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>
2008-04-29 08:06:04 -07:00
Masami Hiramatsu
9960257281 list.h: add list_is_singular()
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>
2008-04-28 08:58:32 -07:00
Linus Torvalds
cc216c5d42 Fix RCU list iterator use of 'rcu_dereference()'
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>
2008-04-21 08:23:35 -07:00
Randy Dunlap
8f731f7d83 kernel-api docbook: fix content problems
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>
2007-10-19 11:53:35 -07:00
Denis V. Lunev
37c42524d6 shrink_dcache_sb speedup
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>
2007-10-17 08:42:57 -07:00
Pavel Emelyanov
768f3591e2 [NETNS]: Cleanup list walking in setup_net and cleanup_net
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>
2007-10-10 16:51:35 -07:00
Daniel Walker
78db2ad6f4 include/linux: trivial repair whitespace damage
Adding tabs where spaces currently are.

Signed-off-by: Daniel Walker <dwalker@mvista.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-12 18:11:06 -07:00
Pavel Emelianov
b5e618181a Introduce a handy list_first_entry macro
There are many places in the kernel where the construction like

   foo = list_entry(head->next, struct foo_struct, list);

are used.
The code might look more descriptive and neat if using the macro

   list_first_entry(head, type, member) \
             list_entry((head)->next, type, member)

Here is the macro itself and the examples of its usage in the generic code.
 If it will turn out to be useful, I can prepare the set of patches to
inject in into arch-specific code, drivers, networking, etc.

Signed-off-by: Pavel Emelianov <xemul@openvz.org>
Signed-off-by: Kirill Korotaev <dev@openvz.org>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Zach Brown <zach.brown@oracle.com>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: John McCutchan <ttb@tentacle.dhs.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08 11:15:11 -07:00
Robert P. J. Day
72fd4a35a8 [PATCH] Numerous fixes to kernel-doc info in source files.
A variety of (mostly) innocuous fixes to the embedded kernel-doc content in
source files, including:

  * make multi-line initial descriptions single line
  * denote some function names, constants and structs as such
  * change erroneous opening '/*' to '/**' in a few places
  * reword some text for clarity

Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
Cc: "Randy.Dunlap" <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-11 10:51:32 -08:00
Corey Minyard
3678d62f02 [PATCH] add an RCU version of list splicing
This patch is in support of the IPMI driver.  I have tested this with the
IPMI driver changes coming in the next patch.

Add a list_splice_init_rcu() function to splice an RCU-protected list into
another list.  This takes the sync function as an argument, so one would do
something like:

	INIT_LIST_HEAD(&list);
	list_splice_init_rcu(&source, &dest, synchronize_rcu);

The idea being to keep the RCU API proliferation down to a dull roar.

[akpm@osdl.org: build fix]
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Corey Minyard <minyard@acm.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-11 10:51:31 -08:00
Robert P. J. Day
45f8bde0d0 [PATCH] fix various kernel-doc in header files
Fix a number of kernel-doc entries for header files in include/linux by
making sure they begin with the appropriate '/**' notation and use @var
notation.

Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-01-26 13:51:00 -08:00
Dave Jones
199a9afc3d [PATCH] Debug variants of linked list macros
Signed-off-by: Dave Jones <davej@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-09-29 09:18:05 -07:00
Shailabh Nagar
e8f4d97e1b [PATCH] list_is_last utility
Add another list utility function to check for last element in a list.

Signed-off-by: Shailabh Nagar <nagar@watson.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-07-14 21:53:56 -07:00
Randy Dunlap
c9cf55285e [PATCH] add poison.h and patch primary users
Localize poison values into one header file for better documentation and
easier/quicker debugging and so that the same values won't be used for
multiple purposes.

Use these constants in core arch., mm, driver, and fs code.

Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Acked-by: Matt Mackall <mpm@selenic.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-27 17:32:38 -07:00