On 2024-09-02 11:43, Peter Zijlstra wrote:
On Wed, Aug 28, 2024 at 10:37:19AM -0400, Mathieu Desnoyers wrote:
To cover scenarios where the scope of the guard differs from the scope
of its activation, introduce DEFINE_INACTIVE_GUARD() and activate_guard().
Here is an example use for a conditionally activated guard variable:
void func(bool a)
{
DEFINE_INACTIVE_GUARD(preempt_notrace, myguard);
[...]
if (a) {
might_sleep();
activate_guard(preempt_notrace, myguard)();
}
[ protected code ]
}
So... I more or less proposed this much earlier:
https://lore.kernel.org/all/[email protected]/T/#mb7b84212619ac743dfe4d2cc81decce451586b27
and Linus took objection to similar patterns. But perhaps my naming
wasn't right.
Then you suggested something like a "guard_if()":
https://lore.kernel.org/lkml/[email protected]/
which I find really odd because it requires to evaluate the same
condition twice within the function if it is used as guard_if
expression and needed as expression within the rest of the function
flow. I find the original patch with labels and gotos less ugly
than the guard_if().
Hence my proposal to optionally separate the definition from the activation,
which nicely integrates with the existing code flow.
If Linus' objections were mainly about naming, perhaps what I am
suggestion here may be more to his liking ?
Thanks,
Mathieu
--
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com
