Eric Lee / smarc-fsl-linux-kernel

27 Sep, 2010

1 commit

25 Sep, 2010

1 commit

  • f064af1e5   net: fix a lockdep splat ... Browse Code »

    We have for each socket :

    One spinlock (sk_slock.slock)
    One rwlock (sk_callback_lock)

    Possible scenarios are :

    (A) (this is used in net/sunrpc/xprtsock.c)
    read_lock(&sk->sk_callback_lock) (without blocking BH)

    spin_lock(&sk->sk_slock.slock);
    ...
    read_lock(&sk->sk_callback_lock);
    ...

    (B)
    write_lock_bh(&sk->sk_callback_lock)
    stuff
    write_unlock_bh(&sk->sk_callback_lock)

    (C)
    spin_lock_bh(&sk->sk_slock)
    ...
    write_lock_bh(&sk->sk_callback_lock)
    stuff
    write_unlock_bh(&sk->sk_callback_lock)
    spin_unlock_bh(&sk->sk_slock)

    This (C) case conflicts with (A) :

    CPU1 [A] CPU2 [C]
    read_lock(callback_lock)
    spin_lock_bh(slock)

    We have one problematic (C) use case in inet_csk_listen_stop() :

    local_bh_disable();
    bh_lock_sock(child); // spin_lock_bh(&sk->sk_slock)
    WARN_ON(sock_owned_by_user(child));
    ...
    sock_orphan(child); // write_lock_bh(&sk->sk_callback_lock)

    lockdep is not happy with this, as reported by Tetsuo Handa

    It seems only way to deal with this is to use read_lock_bh(callbacklock)
    everywhere.

    Thanks to Jarek for pointing a bug in my first attempt and suggesting
    this solution.

    Reported-by: Tetsuo Handa
    Tested-by: Tetsuo Handa
    Signed-off-by: Eric Dumazet
    CC: Jarek Poplawski
    Tested-by: Eric Dumazet
    Signed-off-by: David S. Miller

    Eric Dumazet
     

09 Sep, 2010

2 commits

30 Mar, 2010

1 commit

  • 5a0e3ad6a   include cleanup: Update gfp.h and slab.h includes to prepare for breaking implic… ... Browse Code »

    …it slab.h inclusion from percpu.h

    percpu.h is included by sched.h and module.h and thus ends up being
    included when building most .c files. percpu.h includes slab.h which
    in turn includes gfp.h making everything defined by the two files
    universally available and complicating inclusion dependencies.

    percpu.h -> slab.h dependency is about to be removed. Prepare for
    this change by updating users of gfp and slab facilities include those
    headers directly instead of assuming availability. As this conversion
    needs to touch large number of source files, the following script is
    used as the basis of conversion.

    http://userweb.kernel.org/~tj/misc/slabh-sweep.py

    The script does the followings.

    * Scan files for gfp and slab usages and update includes such that
    only the necessary includes are there. ie. if only gfp is used,
    gfp.h, if slab is used, slab.h.

    * When the script inserts a new include, it looks at the include
    blocks and try to put the new include such that its order conforms
    to its surrounding. It's put in the include block which contains
    core kernel includes, in the same order that the rest are ordered -
    alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
    doesn't seem to be any matching order.

    * If the script can't find a place to put a new include (mostly
    because the file doesn't have fitting include block), it prints out
    an error message indicating which .h file needs to be added to the
    file.

    The conversion was done in the following steps.

    1. The initial automatic conversion of all .c files updated slightly
    over 4000 files, deleting around 700 includes and adding ~480 gfp.h
    and ~3000 slab.h inclusions. The script emitted errors for ~400
    files.

    2. Each error was manually checked. Some didn't need the inclusion,
    some needed manual addition while adding it to implementation .h or
    embedding .c file was more appropriate for others. This step added
    inclusions to around 150 files.

    3. The script was run again and the output was compared to the edits
    from #2 to make sure no file was left behind.

    4. Several build tests were done and a couple of problems were fixed.
    e.g. lib/decompress_*.c used malloc/free() wrappers around slab
    APIs requiring slab.h to be added manually.

    5. The script was run on all .h files but without automatically
    editing them as sprinkling gfp.h and slab.h inclusions around .h
    files could easily lead to inclusion dependency hell. Most gfp.h
    inclusion directives were ignored as stuff from gfp.h was usually
    wildly available and often used in preprocessor macros. Each
    slab.h inclusion directive was examined and added manually as
    necessary.

    6. percpu.h was updated not to include slab.h.

    7. Build test were done on the following configurations and failures
    were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my
    distributed build env didn't work with gcov compiles) and a few
    more options had to be turned off depending on archs to make things
    build (like ipr on powerpc/64 which failed due to missing writeq).

    * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
    * powerpc and powerpc64 SMP allmodconfig
    * sparc and sparc64 SMP allmodconfig
    * ia64 SMP allmodconfig
    * s390 SMP allmodconfig
    * alpha SMP allmodconfig
    * um on x86_64 SMP allmodconfig

    8. percpu.h modifications were reverted so that it could be applied as
    a separate patch and serve as bisection point.

    Given the fact that I had only a couple of failures from tests on step
    6, I'm fairly confident about the coverage of this conversion patch.
    If there is a breakage, it's likely to be something in one of the arch
    headers which should be easily discoverable easily on most builds of
    the specific arch.

    Signed-off-by: Tejun Heo <tj@kernel.org>
    Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
    Cc: Ingo Molnar <mingo@redhat.com>
    Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>

    Tejun Heo
     

04 Feb, 2010

1 commit

19 Oct, 2009

1 commit

  • c720c7e83   inet: rename some inet_sock fields ... Browse Code »

    In order to have better cache layouts of struct sock (separate zones
    for rx/tx paths), we need this preliminary patch.

    Goal is to transfert fields used at lookup time in the first
    read-mostly cache line (inside struct sock_common) and move sk_refcnt
    to a separate cache line (only written by rx path)

    This patch adds inet_ prefix to daddr, rcv_saddr, dport, num, saddr,
    sport and id fields. This allows a future patch to define these
    fields as macros, like sk_refcnt, without name clashes.

    Signed-off-by: Eric Dumazet
    Signed-off-by: David S. Miller

    Eric Dumazet
     

24 Aug, 2009

1 commit

  • 70041088e   RDS: Add TCP transport to RDS ... Browse Code »

    This code allows RDS to be tunneled over a TCP connection.

    RDMA operations are disabled when using TCP transport,
    but this frees RDS from the IB/RDMA stack dependency, and allows
    it to be used with standard Ethernet adapters, or in a VM.

    Signed-off-by: Andy Grover
    Signed-off-by: David S. Miller

    Andy Grover