On 2013-08-27 01:26, Chris Johns wrote:
Sebastian Huber wrote:
On 2013-08-24 04:10, Chris Johns wrote:
Thus the normal extract operation is not available on SMP. An extract
variant which needs also the chain control as a parameter must be used.
I think a node may need a back pointer to the chain control that
contains a
lock. I suspect we cannot have a single score chain control structure
for both
protected and unprotected operations and support the current extract.
I have
not looked at all the uses of extract in the code so I do not know if
the chain
control is available and even it is I think the node should handle this.
In order to use the back pointer you have to lock the chain, so this
cannot be used. You have to know on which chain the node is.
Yes you are correct. Should the locking be something the user of the chains
should manage ? The chains is starting to become more and more complex.
On single processor configuration the locking is done by the chains (ISR
disable/enable) so I think there is no way out. Please have a look at the
patch here:
https://www.rtems.org/pipermail/rtems-devel/2013-August/004370.html
I had to add rtems_chain_explicit_extract() and rtems_chain_explicit_insert()
routines.
--
Sebastian Huber, embedded brains GmbH
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