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| -rw-r--r-- | Documentation/RCU/Design/Requirements/Requirements.rst | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/Documentation/RCU/Design/Requirements/Requirements.rst b/Documentation/RCU/Design/Requirements/Requirements.rst index 75b8ca007a11..a69b5c43a10c 100644 --- a/Documentation/RCU/Design/Requirements/Requirements.rst +++ b/Documentation/RCU/Design/Requirements/Requirements.rst @@ -2583,7 +2583,12 @@ not work to have these markers in the trampoline itself, because there would need to be instructions following ``rcu_read_unlock()``. Although ``synchronize_rcu()`` would guarantee that execution reached the ``rcu_read_unlock()``, it would not be able to guarantee that execution -had completely left the trampoline. +had completely left the trampoline. Worse yet, in some situations +the trampoline's protection must extend a few instructions *prior* to +execution reaching the trampoline. For example, these few instructions +might calculate the address of the trampoline, so that entering the +trampoline would be pre-ordained a surprisingly long time before execution +actually reached the trampoline itself. The solution, in the form of `Tasks RCU <https://lwn.net/Articles/607117/>`__, is to have implicit read-side |