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Date: Mon, 21 Apr 2008 18:33:02 -0700
From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To: Oleg Nesterov <oleg@...sign.ru>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Christoph Hellwig <hch@....de>,
"David S. Miller" <davem@...emloft.net>,
Peter Zijlstra <peterz@...radead.org>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0.01/1] hlist_for_each_entry_xxx: kill the "pos" argument
On Mon, Apr 21, 2008 at 07:14:43PM +0400, Oleg Nesterov wrote:
> (The actual patch is huge, 116K, I'll send it offline. This email contains
> the chunk for list.h only).
>
> COMPILE TESTED ONLY (make allyesconfig).
>
> All hlist_for_each_entry_xxx() macros require the "pos" argument, which is not
> actually needed and can be removed. See the changes in include/linux/list.h
> (note that hlist_for_each_entry_safe() now does prefetch() too).
Now that is what I can a -patch-!!! ;-)
Much as I hate suggesting this... Might it be better to do this in two
phases to allow these patches to be applied incrementally?
1. Change all to "obsolete" __hlist_for_each_entry_xxx().
2. Incrementally change to hlist_for_each_entry_xxx(), removing
the extra variable where possible.
Thanx, Paul
> Now we should convert the callers somehow. Unfortunately, this is not always
> easy. Consider this code for example:
>
> {
> struct hlist_node *tmp1, *tmp2;
>
> hlist_for_each_entry(pos, tmp1, head,mem)
> do_something(pos);
>
> hlist_for_each_entry(pos, tmp2, head,mem)
> use(tmp2);
> }
>
> The first hlist_for_each_entry is easy, but the second can't be converted
> automatically because "tmp2" is used.
>
> So, this patch
>
> - copies these macros to "obsolete" __hlist_for_each_entry_xxx()
>
> - changes hlist_for_each_entry_xxxx() to avoid the "struct hlist_nod*"
>
> - converts the rest of the kernel to use either new or old macros
>
> For example, the patch for the code above is
>
> {
> - struct hlist_node *tmp1, *tmp2;
> + struct hlist_node *tmp2;
>
> - hlist_for_each_entry(pos, tmp1, head,mem)
> + hlist_for_each_entry(pos, head,mem)
> do_something(pos);
>
> - hlist_for_each_entry(pos, tmp2, head,mem)
> + __hlist_for_each_entry(pos, tmp2, head,mem)
> use(tmp2);
> }
>
> I believe it is very easy to convert the users of the obsolete macros, but
> this needs separate patches.
>
> Except for changes in include/linux/list.h the patch was generated by this
> script:
>
> #!/usr/bin/perl -w
> use strict;
>
> my ($N_CNT, $O_CNT, @SRC, $CTXT, @CTXT);
>
> sub say { printf STDERR "%4d: %s.\n", $., "@_" }
>
> sub var { return $_->{$_[0]} || next for @CTXT }
>
> sub parse_line
> {
> if (ord == ord '{') {
> unshift @CTXT, $CTXT = {
> -v_list => \@{$CTXT->{-v_list}},
> -v_rexp => $CTXT->{-v_rexp},
> };
> }
> elsif (ord == ord '}') {
> say "WARN! unmatched '}'" unless $CTXT;
>
> while (my ($v, $c) = each %$CTXT) {
> my $trim = ord $v != ord '-' &&
> !$c->{used} && $c->{trim} || next;
>
> for my $tr (@$trim) {
> substr($_, $tr->[1], 2, ''),
> substr($_, $tr->[2], $tr->[3], '')
> for $SRC[$tr->[0]];
> $N_CNT++;
> }
>
> for ($SRC[$c->{decl}]) {
> s/\* \s* $v \b (?: \s* , \s*)?//x || die;
> s/,\s*(?=;)//; s/\bstruct\s+hlist_node\s*;//;
> $_ = '' if /^\s*\\?\s*$/;
> }
> }
> shift @CTXT; $CTXT = $CTXT[0];
> }
> elsif ($CTXT && /\b struct \s+ hlist_node \b ([^;]+)/x) {
> my $v_list = $CTXT->{-v_list};
> for (split /,/, $1) {
> /^\s* \* (\w+) \s* \z/x or next;
> $CTXT->{$1} = { decl => 0+@SRC };
> push @$v_list, $1;
> }
> $CTXT->{-v_rexp} = qr/\b(@{[join '|', @$v_list]})\b/
> if @$v_list;
> }
> elsif (/\b hlist_for_each_entry (?:_continue|_from|_safe|_rcu)? \b/xg) {
> my $u = length $`;
> if (/\G \s* \( .+? (, \s* (\w+) \s*)/x) {
> my $tr = [0+@SRC, $u, $-[1], length $1];
> if (my $v = var $2) { push @{$v->{trim}}, $tr; }
> } else {
> say "suspicious usage of hlist_for_each_entry_xxx()";
> }
> substr $_, $u, 0, '__';
> $O_CNT++;
> }
> elsif (my $re = $CTXT && $CTXT->{-v_rexp}) {
> var($1)->{used}++ while /$re/g;
> }
>
> push @SRC, $_;
> }
>
> sub diff_file
> {
> my $file = $_;
> warn "====> $file ...\n";
> ($N_CNT, $O_CNT, @SRC, $CTXT, @CTXT) = 0;
>
> open my $fd, '<', $file or die;
> while (<$fd>) {
> my $comm = s/(\/\*.*)//s && $1;
> parse_line for split /([{}])/, $_, -1;
> while ($comm) {
> push @SRC, $comm;
> $comm = $comm !~ /\*\// && <$fd>;
> }
> }
>
> warn "WARN! unmatched '{'\n" if $CTXT;
> return warn "WARN! not changed\n" unless $O_CNT;
> warn "stat: $N_CNT from $O_CNT\n";
>
> open my $diff, "|diff -up --label a/$file $file --label b/$file -";
> print $diff @SRC;
> }
>
>
> @ARGV || die "usage: $0 path_to_kernel || list_of_files\n";
>
> if (-d $ARGV[0]) {
> chdir $ARGV[0] || die "ERR!! can't cd to $ARGV[0]\n";
> warn "grep ...\n";
> @ARGV = sort grep {
> chomp; s/^\.\///; $_ ne 'include/linux/list.h';
> } qx{grep --include='*.[ch]' -rle '\\bhlist_for_each_entry' .};
> }
>
> diff_file for @ARGV;
>
> (it open files readonly, so can be used safely)
>
> Signed-off-by: Oleg Nesterov <oleg@...sign.ru>
>
> arch/arm/kernel/kprobes.c | 6 +--
> arch/ia64/kernel/kprobes.c | 8 ++--
> arch/powerpc/kernel/kprobes.c | 6 +--
> arch/s390/kernel/kprobes.c | 6 +--
> arch/sparc64/kernel/kprobes.c | 6 +--
> arch/sparc64/kernel/ldc.c | 3 -
> arch/x86/kernel/kprobes.c | 6 +--
> arch/x86/kvm/mmu.c | 20 ++++------
> block/cfq-iosched.c | 3 -
> block/elevator.c | 4 +-
> crypto/algapi.c | 6 +--
> drivers/infiniband/core/cma.c | 3 -
> drivers/infiniband/core/fmr_pool.c | 3 -
> drivers/md/raid5.c | 6 +--
> drivers/net/macvlan.c | 6 +--
> drivers/net/pppol2tp.c | 6 +--
> drivers/net/sunvnet.c | 3 -
> drivers/net/wireless/zd1201.c | 7 +--
> fs/dcache.c | 3 -
> fs/ecryptfs/messaging.c | 5 +-
> fs/fat/inode.c | 3 -
> fs/gfs2/glock.c | 6 +--
> fs/lockd/host.c | 17 +++------
> fs/lockd/svcsubs.c | 7 +--
> fs/nfsd/nfscache.c | 3 -
> fs/ocfs2/dlm/dlmdebug.c | 3 -
> fs/ocfs2/dlm/dlmrecovery.c | 6 +--
> fs/xfs/xfs_inode.c | 3 -
> include/linux/pci.h | 3 -
> include/linux/pid.h | 3 -
> include/net/ax25.h | 4 +-
> include/net/inet_hashtables.h | 2 -
> include/net/inet_timewait_sock.h | 6 +--
> include/net/netrom.h | 8 ++--
> include/net/sctp/sctp.h | 2 -
> include/net/sock.h | 10 ++---
> kernel/kprobes.c | 36 ++++++++-----------
> kernel/marker.c | 15 ++------
> kernel/pid.c | 3 -
> kernel/sched.c | 6 +--
> kernel/user.c | 3 -
> net/8021q/vlan.c | 3 -
> net/9p/error.c | 2 -
> net/atm/lec.c | 64 +++++++++++++++--------------------
> net/ax25/ax25_iface.c | 3 -
> net/bridge/br_fdb.c | 17 +++------
> net/can/af_can.c | 21 +++++------
> net/can/proc.c | 6 +--
> net/decnet/dn_table.c | 13 ++-----
> net/ipv4/fib_frontend.c | 11 ++----
> net/ipv4/fib_hash.c | 30 ++++++----------
> net/ipv4/fib_semantics.c | 23 ++++--------
> net/ipv4/fib_trie.c | 25 ++++---------
> net/ipv4/inet_fragment.c | 10 ++---
> net/ipv4/netfilter/nf_nat_core.c | 3 -
> net/ipv6/addrlabel.c | 14 +++----
> net/ipv6/ip6_fib.c | 9 +---
> net/ipv6/xfrm6_tunnel.c | 12 ++----
> net/netfilter/nf_conntrack_core.c | 18 +++------
> net/netfilter/nf_conntrack_expect.c | 12 ++----
> net/netfilter/nf_conntrack_helper.c | 14 +++----
> net/netfilter/nf_conntrack_netlink.c | 12 ++----
> net/netfilter/nfnetlink_log.c | 7 +--
> net/netfilter/nfnetlink_queue.c | 10 ++---
> net/netfilter/xt_RATEEST.c | 3 -
> net/netfilter/xt_hashlimit.c | 13 ++-----
> net/sched/sch_htb.c | 9 +---
> net/sunrpc/auth.c | 5 +-
> net/sunrpc/svcauth.c | 3 -
> net/tipc/name_table.c | 8 +---
> net/xfrm/xfrm_policy.c | 53 ++++++++++++----------------
> net/xfrm/xfrm_state.c | 43 ++++++++---------------
> 72 files changed, 302 insertions(+), 439 deletions(-)
>
> --- HL/include/linux/list.h~HLIST 2007-10-25 16:22:12.000000000 +0400
> +++ HL/include/linux/list.h 2008-04-21 17:17:44.000000000 +0400
> @@ -926,58 +926,54 @@ static inline void hlist_add_after_rcu(s
>
> /**
> * hlist_for_each_entry - iterate over list of given type
> - * @tpos: the type * to use as a loop cursor.
> - * @pos: the &struct hlist_node to use as a loop cursor.
> + * @pos: the type * to use as a loop cursor.
> * @head: the head for your list.
> * @member: the name of the hlist_node within the struct.
> */
> -#define hlist_for_each_entry(tpos, pos, head, member) \
> - for (pos = (head)->first; \
> - pos && ({ prefetch(pos->next); 1;}) && \
> - ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
> - pos = pos->next)
> +#define hlist_for_each_entry(pos, head, member) \
> + for (pos = (void*)(head)->first; pos && ({ \
> + prefetch(((struct hlist_node*)pos)->next); \
> + pos = hlist_entry((void*)pos, typeof(*pos), member); 1; \
> + }); pos = (void*)(pos)->member.next)
>
> /**
> * hlist_for_each_entry_continue - iterate over a hlist continuing after current point
> - * @tpos: the type * to use as a loop cursor.
> - * @pos: the &struct hlist_node to use as a loop cursor.
> + * @pos: the type * to use as a loop cursor.
> * @member: the name of the hlist_node within the struct.
> */
> -#define hlist_for_each_entry_continue(tpos, pos, member) \
> - for (pos = (pos)->next; \
> - pos && ({ prefetch(pos->next); 1;}) && \
> - ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
> - pos = pos->next)
> +#define hlist_for_each_entry_continue(pos, member) \
> + for (; (pos = (void*)(pos)->member.next) && ({ \
> + prefetch(((struct hlist_node*)pos)->next); \
> + pos = hlist_entry((void*)pos, typeof(*pos), member); 1; \
> + }); )
>
> /**
> * hlist_for_each_entry_from - iterate over a hlist continuing from current point
> - * @tpos: the type * to use as a loop cursor.
> - * @pos: the &struct hlist_node to use as a loop cursor.
> + * @pos: the type * to use as a loop cursor.
> * @member: the name of the hlist_node within the struct.
> */
> -#define hlist_for_each_entry_from(tpos, pos, member) \
> - for (; pos && ({ prefetch(pos->next); 1;}) && \
> - ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
> - pos = pos->next)
> +#define hlist_for_each_entry_from(pos, member) \
> + for (pos = pos ? (void*)&(pos)->member.next : pos; pos && ({ \
> + prefetch(((struct hlist_node*)pos)->next); \
> + pos = hlist_entry((void*)pos, typeof(*pos), member); 1; \
> + }); pos = (void*)(pos)->member.next)
>
> /**
> * hlist_for_each_entry_safe - iterate over list of given type safe against removal of list entry
> - * @tpos: the type * to use as a loop cursor.
> - * @pos: the &struct hlist_node to use as a loop cursor.
> + * @pos: the type * to use as a loop cursor.
> * @n: another &struct hlist_node to use as temporary storage
> * @head: the head for your list.
> * @member: the name of the hlist_node within the struct.
> */
> -#define hlist_for_each_entry_safe(tpos, pos, n, head, member) \
> - for (pos = (head)->first; \
> - pos && ({ n = pos->next; 1; }) && \
> - ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
> - pos = n)
> +#define hlist_for_each_entry_safe(pos, n, head, member) \
> + for (pos = (void*)(head)->first; pos && ({ \
> + n = ((struct hlist_node*)pos)->next; prefetch(n); \
> + pos = hlist_entry((void*)pos, typeof(*pos), member); 1; \
> + }); pos = (void*)n)
>
> /**
> * hlist_for_each_entry_rcu - iterate over rcu list of given type
> - * @tpos: the type * to use as a loop cursor.
> - * @pos: the &struct hlist_node to use as a loop cursor.
> + * @pos: the type * to use as a loop cursor.
> * @head: the head for your list.
> * @member: the name of the hlist_node within the struct.
> *
> @@ -985,7 +981,38 @@ static inline void hlist_add_after_rcu(s
> * the _rcu list-mutation primitives such as hlist_add_head_rcu()
> * as long as the traversal is guarded by rcu_read_lock().
> */
> -#define hlist_for_each_entry_rcu(tpos, pos, head, member) \
> +#define hlist_for_each_entry_rcu(pos, head, member) \
> + for (pos = (void*)(head)->first; rcu_dereference(pos) && ({ \
> + prefetch(((struct hlist_node*)pos)->next); \
> + pos = hlist_entry((void*)pos, typeof(*pos), member); 1; \
> + }); pos = (void*)(pos)->member.next)
> +
> +/* -------- Obsolete, to be removed soon, do not use -------- */
> +
> +#define __hlist_for_each_entry(tpos, pos, head, member) \
> + for (pos = (head)->first; \
> + pos && ({ prefetch(pos->next); 1;}) && \
> + ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
> + pos = pos->next)
> +
> +#define __hlist_for_each_entry_continue(tpos, pos, member) \
> + for (pos = (pos)->next; \
> + pos && ({ prefetch(pos->next); 1;}) && \
> + ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
> + pos = pos->next)
> +
> +#define __hlist_for_each_entry_from(tpos, pos, member) \
> + for (; pos && ({ prefetch(pos->next); 1;}) && \
> + ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
> + pos = pos->next)
> +
> +#define __hlist_for_each_entry_safe(tpos, pos, n, head, member) \
> + for (pos = (head)->first; \
> + pos && ({ n = pos->next; 1; }) && \
> + ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
> + pos = n)
> +
> +#define __hlist_for_each_entry_rcu(tpos, pos, head, member) \
> for (pos = (head)->first; \
> rcu_dereference(pos) && ({ prefetch(pos->next); 1;}) && \
> ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
>
--
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