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    SubjectRe: [RFC][PATCH 0/3] configfs: Make nested default groups lockdep-friendly
    Arjan van de Ven a écrit :
    > On Tue, 20 May 2008 18:33:20 +0200
    > Louis Rilling <Louis.Rilling@kerlabs.com> wrote:
    >
    >> Hi all,
    >>
    >> The following patches fix lockdep warnings resulting from (correct)
    >> recursive locking in configfs.
    >>
    >> Current lockdep annotations for inode mutexes in configfs are
    >> lockdep-friendly provided that:
    >> 1/ config_groups have at most one level of default groups (see
    >> configfs_attach_group()),
    >> 2/ config_groups having default groups are never removed (see
    >> configfs_detach_prep()).
    >>
    >> Since lockdep does not handle such correct recursion, the idea is to
    >> insert lockdep_off()/lockdep_on() for inode mutexes as soon as the
    >> level of recursion of the I_MUTEX_PARENT -> I_MUTEX_CHILD dependency
    >> pattern increases.
    >
    > I'm... not entirely happy with such a solution ;(
    >
    > there must be a better one.

    Hmm, to me there are three solutions:

    1/ keep lockdep and configfs like they are, and use this patchset

    2/ enhance lockdep to handle wariable-depth but correct recursion:
    seems uncertain...


    3/ remove this recursive locking from configfs:
    unfortunately, it seems that there are a good reasons for doing
    recursive inode locking, at least when removing a config_group with
    default groups. So, seems uncertain too...

    Other ideas?

    --
    Dr Louis Rilling Kerlabs
    Skype: louis.rilling Batiment Germanium
    Phone: (+33|0) 6 80 89 08 23 80 avenue des Buttes de Coesmes
    http://www.kerlabs.com/ 35700 Rennes
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