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rcu: add shiny new debug assists to Documentation/RCU/checklist.txt

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Add a section describing PROVE_RCU, DEBUG_OBJECTS_RCU_HEAD, and
the __rcu sparse checking to the RCU checklist.

Suggested-by: David Miller <davem@davemloft.net>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
This commit is contained in:
Paul E. McKenney 2010-06-16 16:48:13 -07:00
parent 4b6a2872a2
commit 84483ea42c
1 changed files with 23 additions and 0 deletions
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Documentation/RCU/checklist.txt
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@ -365,3 +365,26 @@ over a rather long period of time, but improvements are always welcome!
and the compiler to freely reorder code into and out of RCU and the compiler to freely reorder code into and out of RCU
read-side critical sections. It is the responsibility of the read-side critical sections. It is the responsibility of the
RCU update-side primitives to deal with this. RCU update-side primitives to deal with this.
17. Use CONFIG_PROVE_RCU, CONFIG_DEBUG_OBJECTS_RCU_HEAD, and
the __rcu sparse checks to validate your RCU code. These
can help find problems as follows:
CONFIG_PROVE_RCU: check that accesses to RCU-protected data
structures are carried out under the proper RCU
read-side critical section, while holding the right
combination of locks, or whatever other conditions
are appropriate.
CONFIG_DEBUG_OBJECTS_RCU_HEAD: check that you don't pass the
same object to call_rcu() (or friends) before an RCU
grace period has elapsed since the last time that you
passed that same object to call_rcu() (or friends).
__rcu sparse checks: tag the pointer to the RCU-protected data
structure with __rcu, and sparse will warn you if you
access that pointer without the services of one of the
variants of rcu_dereference().
These debugging aids can help you find problems that are
otherwise extremely difficult to spot.