"Nicholas Piggin" [off-list ref] writes:

On Sat Nov 19, 2022 at 1:07 AM AEST, Nathan Lynch wrote:

quoted

rtas_os_term() is called during panic. Its behavior depends on a
couple of conditions in the /rtas node of the device tree, the
traversal of which entails locking and local IRQ state changes. If the
kernel panics while devtree_lock is held, rtas_os_term() as currently
written could hang.

Nice.

quoted

Instead of discovering the relevant characteristics at panic time,
cache them in file-static variables at boot. Note the lookup for
"ibm,extended-os-term" is converted to of_property_read_bool() since
it is a boolean property, not a RTAS function token.

Small nit, but you could do that at the query site unless you
were going to start using ibm,os-term without the extended
capability.

I'm unsure that this is what you're suggesting, but we don't want to use
of_property_read_bool() in this context either, because it has the same
undesirable qualities as rtas_token().

Reviewed-by: Nicholas Piggin <npiggin@gmail.com>

Thanks!