21 Jul, 2011
1 commit
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If the list to be spliced is empty, then list_splice_init_rcu() has
nothing to do. Unfortunately, list_splice_init_rcu() does not check
the list to be spliced; it instead checks the list to be spliced into.
This results in memory leaks given current usage. This commit
therefore fixes the empty-list check.Signed-off-by: Jan H. Schönherr
Signed-off-by: Paul E. McKenney
20 May, 2011
2 commits
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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 with , because the
use of LIST_POISON ends up needing it. 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
Acked-by: David S. Miller
Cc: linux-arch@vger.kernel.org
Signed-off-by: Linus Torvalds -
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
Acked-by: David S. Miller
Cc: linux-arch@vger.kernel.org
Signed-off-by: Linus Torvalds
18 Dec, 2010
2 commits
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Signed-off-by: Paul E. McKenney
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This restores parentheses blance.
Signed-off-by: Mariusz Kozlowski
Signed-off-by: Paul E. McKenney
21 Aug, 2010
1 commit
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Because list_empty() does not dereference any RCU-protected pointers, and
further does not pass such pointers to the caller (so that the caller
does not dereference them either), it is safe to use list_empty() on
RCU-protected lists. There is no need for a list_empty_rcu(). This
commit adds a comment stating this explicitly.Requested-by: Andrew Morton
Signed-off-by: Paul E. McKenney
20 Aug, 2010
1 commit
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This avoids warnings from missing __rcu annotations
in the rculist implementation, making it possible to
use the same lists in both RCU and non-RCU cases.We can add rculist annotations later, together with
lockdep support for rculist, which is missing as well,
but that may involve changing all the users.Signed-off-by: Arnd Bergmann
Signed-off-by: Paul E. McKenney
Cc: Pavel Emelyanov
Cc: Sukadev Bhattiprolu
Reviewed-by: Josh Triplett
04 May, 2010
1 commit
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Add hlist_for_each_entry_rcu_bh() and
hlist_for_each_entry_continue_rcu_bh() macros, and use them in
ipv6_get_ifaddr(), if6_get_first() and if6_get_next() to fix lockdeps
warnings.Signed-off-by: Eric Dumazet
Reviewed-by: "Paul E. McKenney"
Signed-off-by: David S. Miller
21 Mar, 2010
1 commit
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Convert from reader/writer lock to RCU and spinlock for addrconf
hash list.Adds an additional helper macro for hlist_for_each_entry_continue_rcu
to handle the continue case.Signed-off-by: Stephen Hemminger
Signed-off-by: David S. Miller
01 Mar, 2010
1 commit
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Conflicts:
drivers/firmware/iscsi_ibft.c
25 Feb, 2010
1 commit
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The theory is that use of bare rcu_dereference() is more prone
to error than use of the RCU list-traversal primitives.
Therefore, disable lockdep RCU read-side critical-section
checking in these primitives for the time being. Once all of
the rcu_dereference() uses have been dealt with, it may be time
to re-enable lockdep checking for the RCU list-traversal
primitives.Signed-off-by: Paul E. McKenney
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference:
Signed-off-by: Ingo Molnar
23 Feb, 2010
1 commit
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Many usages of seq_file use RCU protected lists, so non RCU
iterators will not work safely.Signed-off-by: Stephen Hemminger
Signed-off-by: David S. Miller
11 Nov, 2009
1 commit
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This adds an RCU macro for continuing search, useful for some
network devices like vlan.Signed-off-by: Stephen Hemminger
Acked-by: Eric Dumazet
Signed-off-by: David S. Miller
15 Apr, 2009
1 commit
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I've run into the situation where I need to use list_first_entry with
rcu-guarded list. This patch introduces this.Also simplify list_for_each_entry_rcu() to use new list_entry_rcu()
instead of list_entry().Signed-off-by: Jiri Pirko
Reviewed-by: Paul E. McKenney
Cc: dipankar@in.ibm.com
LKML-Reference:
Signed-off-by: Ingo Molnar
15 Aug, 2008
1 commit
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All of the in-tree uses of list_for_each_rcu() have been converted to
list_for_each_entry_rcu(), so list_for_each_rcu() can now be removed.Signed-off-by: Paul E. McKenney
Signed-off-by: Ingo Molnar
29 Jul, 2008
1 commit
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Introduce list_del_init_rcu() and document it.
Signed-off-by: Andrea Arcangeli
Acked-by: Linus Torvalds
Cc: "Paul E. McKenney"
Cc: Ingo Molnar
Cc: Christoph Lameter
Cc: Jack Steiner
Cc: Robin Holt
Cc: Nick Piggin
Cc: Peter Zijlstra
Cc: Kanoj Sarcar
Cc: Roland Dreier
Cc: Steve Wise
Cc: Avi Kivity
Cc: Hugh Dickins
Cc: Rusty Russell
Cc: Anthony Liguori
Cc: Chris Wright
Cc: Marcelo Tosatti
Cc: Eric Dumazet
Cc: "Paul E. McKenney"
Cc: Izik Eidus
Cc: Anthony Liguori
Cc: Rik van Riel
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
19 May, 2008
3 commits
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RCU list iterators: should prefetch ever be optimised out with no
side-effects, the current version will lose the barrier completely.Pointed-out-by: Linus Torvalds
Signed-off-by: Paul E. McKenney
Signed-off-by: Ingo Molnar -
Make almost all list mutation primitives use rcu_assign_pointer().
The main point of this being readability improvement.
Signed-off-by: Franck Bui-Huu
Cc: "Paul E. McKenney"
Cc: Josh Triplett
Signed-off-by: Andrew Morton
Signed-off-by: Ingo Molnar -
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
Acked-by: Paul E. McKenney
Acked-by: Josh Triplett
Signed-off-by: Andrew Morton
Signed-off-by: Ingo Molnar
