Does CONFIG_PARAVIRT imply usage of byte locks?

From: Jiri Kosina
Date: Fri Jan 09 2009 - 16:58:29 EST


Hi,

in [1] Linus states that CONFIG_PARAVIRT implies usage of inferior locks.

Looking at the code, I wonder whether are we in fact really using byte
locks in CONFIG_PARAVIRT situation? Where are we actually setting
pv_lock_ops.spin_lock pointer to point to __byte_spin_lock?

Such initialization seems to happen only in paravirt_use_bytelocks()
function, but my blind eyes prevent me from finding a callsite from which
this function would eventually get called.

It seems to me that paravirt_use_bytelocks() is a dead code that gets
never called, and the same applies to the implementations of write locks.
What did I miss?

[1] http://marc.info/?l=linux-kernel&m=123144211719754&w=2

Thanks,

--
Jiri Kosina
SUSE Labs
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