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    SubjectRe: [RFC PATCH 4/5] RCU: Add TASK_RCU_OFFSET
    On 04/11/2011 01:12 PM, Paul E. McKenney wrote:
    > On Mon, Apr 11, 2011 at 11:08:14AM +0800, Lai Jiangshan wrote:
    >> On 04/08/2011 01:13 PM, Paul E. McKenney wrote:
    >>> On Fri, Apr 08, 2011 at 09:26:16AM +0800, Lai Jiangshan wrote:
    >>>> On 04/08/2011 12:26 AM, Paul E. McKenney wrote:
    >>>>> On Thu, Apr 07, 2011 at 08:47:37AM -0700, Paul E. McKenney wrote:
    >>>>>> On Thu, Apr 07, 2011 at 01:49:51PM +0800, Lai Jiangshan wrote:
    >>>>>>> On 04/07/2011 08:30 AM, Paul E. McKenney wrote:
    >>>>>>>> On Wed, Apr 06, 2011 at 02:27:39PM -0700, H. Peter Anvin wrote:
    >>>>>>>>> On 04/06/2011 02:06 PM, Peter Zijlstra wrote:
    >>>>>>>>>> On Wed, 2011-04-06 at 13:13 -0700, Paul E. McKenney wrote:
    >>>>>>>>>>> And the following patch builds correctly for defconfig x86 builds,
    >>>>>>>>>>> while allowing rcupdate.h to see the sched.h definitions as needed
    >>>>>>>>>>> to inline rcu_read_lock() and rcu_read_unlock().
    >>>>>>>>>>>
    >>>>>>>>>> Looks like an entirely reasonable patch to me ;-)
    >>>>>>>>>>
    >>>>>>>>>
    >>>>>>>>> Quite... a lot better than the original proposal!
    >>>>>>>>
    >>>>>>>> Glad you both like it!
    >>>>>>>>
    >>>>>>>> When I do an allyesconfig build, I do get errors during the "CHECK"
    >>>>>>>> phase, when it is putting things into the usr/include in the build tree.
    >>>>>>>> I believe that this is because I am exposing different header files to
    >>>>>>>> the library-export scripts. The following patch silences some of them,
    >>>>>>>> but I am really out of my depth here.
    >>>>>>>>
    >>>>>>>> Sam, Jan, Michal, help?
    >>>>>>>>
    >>>>>>>> Thanx, Paul
    >>>>>>>>
    >>>>>>>> ------------------------------------------------------------------------
    >>>>>>>>
    >>>>>>>
    >>>>>>> Easy to split rcupdate.h, hard to resolve the dependence problem.
    >>>>>>>
    >>>>>>> You can apply the next additional patch when you test:
    >>>>>>
    >>>>>> I am sure that you are quite correct. ;-)
    >>>>>>
    >>>>>> I am moving _rcu_read_lock() and _rcu_read_unlock() into
    >>>>>> include/linux/rcutree.h and include/linux/rcutiny.h, and I am sure that
    >>>>>> more pain will ensue.
    >>>>>>
    >>>>>> One thing I don't understand... How does is it helping to group the
    >>>>>> task_struct RCU-related fields into a structure? Is that generating
    >>>>>> better code on your platform due to smaller offsets or something?
    >>>>
    >>>> You don't like task_rcu_struct patch? I think it can make code clearer,
    >>>> and it can also check the code even when CONFIG_PREEMPT_RCU=n.
    >>>>
    >>>> For rcu_read_[un]lock(), it generates the same code, no better, no worse.
    >>>>
    >>>> It is just a cleanup patch, it is helpless for making rcu_read_[un]lock() inline,
    >>>> if you don't like it, I will give up it.
    >>>
    >>> I don't know that I feel strongly either way about it. It was necessary
    >>> with the integer-offset approach, but optional now.
    >>>
    >>>>>> Also, does your patchset address the CHECK warnings?
    >>>>>
    >>>>> I take it back... I applied the following patch on top of my earlier
    >>>>> one, and a defconfig x86 build completed without error. (Though I have
    >>>>> not tested the results of the build.)
    >>>>>
    >>>>> One possible difference -- I did this work on top of a recent Linus
    >>>>> git commit (b2a8b4b81966) rather than on top of my -rcu tree. Also,
    >>>>> I have not yet tried an allyesconfig build, which will no doubt locate
    >>>>> some more problems.
    >>>>>
    >>>>> Thanx, Paul
    >>>>>
    >>>>
    >>>> when defconfig or allyesconfig, CONFIG_PREEMPT=n and CONFIG_TREE_PREEMPT_RCU=n
    >>>> when you make them "y":
    >>>>
    >>>> In file included from include/linux/rcupdate.h:764:0,
    >>>> from include/linux/tracepoint.h:19,
    >>>> from include/linux/module.h:18,
    >>>> from include/linux/crypto.h:21,
    >>>> from arch/x86/kernel/asm-offsets.c:8:
    >>>> include/linux/rcutree.h:50:20: error: static declaration of ‘__rcu_read_lock’ follows non-static declaration
    >>>> include/linux/rcupdate.h:76:13: note: previous declaration of ‘__rcu_read_lock’ was here
    >>>> include/linux/rcutree.h:63:20: error: static declaration of ‘__rcu_read_unlock’ follows non-static declaration
    >>>> include/linux/rcupdate.h:77:13: note: previous declaration of ‘__rcu_read_unlock’ was here
    >>>> make[1]: *** [arch/x86/kernel/asm-offsets.s] Error 1
    >>>> make: *** [prepare0] Error 2
    >>>
    >>> Yep. I need to move the rcu_read_lock() APIs to follow the inclusion
    >>> of rcutree.h and rcutiny.h. Also add include of sched.h to rcutiny.h.
    >>> The code movement does bloat the patch a bit. But rcu_assign_pointer()
    >>> must precede the inclusion of rcutree.h and rcutiny.h, so it is not
    >>> possible to simply move the inclusions. See below.
    >>>
    >>> Thanx, Paul
    >>>
    >>
    >> sched.h still contains rcupdate.h after applied this patch.
    >
    > Then we are not in sync -- sched.h does not include rcupdate.h in my tree.
    > It instead gets the struct rcu_head definition from include/linux/types.h.
    > See below for a consolidated patch.
    >
    > Thanx, Paul
    >
    >> See my [PATCH 2/4] for more info.
    >>
    >>
    >> # make lib/is_single_threaded.o
    >> CHK include/linux/version.h
    >> CHK include/generated/utsrelease.h
    >> CALL scripts/checksyscalls.sh
    >> CC lib/is_single_threaded.o
    >> In file included from include/linux/rcupdate.h:639:0,
    >> from include/linux/rculist.h:10,
    >> from include/linux/sched.h:82,
    >> from lib/is_single_threaded.c:13:
    >> include/linux/rcutree.h: In function ‘__rcu_read_lock’:
    >> include/linux/rcutree.h:52:15: error: dereferencing pointer to incomplete type
    >> In file included from include/linux/rcupdate.h:639:0,
    >> from include/linux/rculist.h:10,
    >> from include/linux/sched.h:82,
    >> from lib/is_single_threaded.c:13:
    >> include/linux/rcutree.h: In function ‘__rcu_read_unlock’:
    >> include/linux/rcutree.h:68:5: error: dereferencing pointer to incomplete type
    >> include/linux/rcutree.h:70:7: error: dereferencing pointer to incomplete type
    >> include/linux/rcutree.h:71:46: error: dereferencing pointer to incomplete type
    >> include/linux/rcutree.h:71:78: error: dereferencing pointer to incomplete type
    >> include/linux/rcutree.h:71:6: warning: type defaults to ‘int’ in type name
    >> make[1]: *** [lib/is_single_threaded.o] Error 1
    >> make: *** [lib/is_single_threaded.o] Error 2
    >
    > drivers/scsi/scsi_sysctl.c | 1 +
    > fs/proc/proc_sysctl.c | 1 +
    > include/linux/kernel.h | 3 +++
    > include/linux/pid.h | 2 +-
    > include/linux/rcupdate.h | 29 +++++++++--------------------
    > include/linux/rcutiny.h | 35 +++++++++++++++++++++++++++++++++++
    > include/linux/rcutree.h | 37 +++++++++++++++++++++++++++++++++++++
    > include/linux/sched.h | 10 ++++------
    > include/linux/sem.h | 2 +-
    > include/linux/soundcard.h | 2 ++
    > include/linux/sysctl.h | 5 +++--
    > include/linux/types.h | 10 ++++++++++
    > kernel/pid_namespace.c | 2 ++
    > kernel/rcutiny_plugin.h | 38 ++------------------------------------
    > kernel/rcutree_plugin.h | 38 ++------------------------------------
    > kernel/sysctl_binary.c | 1 +
    > kernel/sysctl_check.c | 1 +
    > net/core/sysctl_net_core.c | 1 +
    > net/dccp/sysctl.c | 1 +
    > net/ipv6/sysctl_net_ipv6.c | 1 +
    > net/irda/irsysctl.c | 1 +
    > net/phonet/sysctl.c | 1 +
    > net/rds/ib_sysctl.c | 1 +
    > net/rds/iw_sysctl.c | 1 +
    > net/rds/sysctl.c | 1 +
    > net/sctp/sysctl.c | 1 +
    > net/sunrpc/sysctl.c | 1 +
    > net/unix/sysctl_net_unix.c | 1 +
    > net/xfrm/xfrm_sysctl.c | 1 +
    > 29 files changed, 127 insertions(+), 102 deletions(-)
    >

    sched.h still contains rcupdate.h after applied this patch.
    so it still fails.

    Is other part of patch(or patch 2/2) not sent?
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