Messages in this thread | | | Date | Tue, 30 May 2006 23:06:25 +0200 | From | Ingo Molnar <> | Subject | Re: [patch 38/61] lock validator: special locking: i_mutex |
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* Steven Rostedt <rostedt@goodmis.org> wrote:
> On Mon, 2006-05-29 at 23:26 +0200, Ingo Molnar wrote: > > + * inode->i_mutex nesting types for the LOCKDEP validator: > > + * > > + * 0: the object of the current VFS operation > > + * 1: parent > > + * 2: child/target > > + */ > > +enum inode_i_mutex_lock_type > > +{ > > + I_MUTEX_NORMAL, > > + I_MUTEX_PARENT, > > + I_MUTEX_CHILD > > +}; > > + > > +/* > > I guess we can say the same about I_MUTEX_NORMAL.
yeah. Subtypes start from 1, as 0 is the basic type.
Lock types are keyed via static kernel addresses. This means that we can use the lock address (for DEFINE_SPINLOCK) or the static key embedded in spin_lock_init() as a key in 99% of the cases. The key [struct lockdep_type_key, see include/linux/lockdep.h] occupies enough bytes (of kernel static virtual memory) so that the keys remain automatically unique. Right now MAX_LOKCDEP_SUBTYPES is 8, so the keys take at most 8 bytes. (To save some memory there's another detail: for static locks (DEFINE_SPINLOCK ones) we use the lock address itself as the key.)
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