On 2023-10-27 12:49, Steven Rostedt wrote:
On Fri, 27 Oct 2023 12:35:56 -0400
Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> wrote:
Does that make more sense?
Not really.
Please see my other email about the need for a reference count here, for
nested locks use-cases.
Note, my original implementation of nested locking was done completely in
user space.
int __thread lock_cnt;
extend() {
if (lock_cnt++)
return;
...
}
unextend() {
if (--lock_cnt)
return;
...
}
This only works if "your" lock implementation is the only user of this
RSEQ feature within a process. RSEQ requires that multiple libraries can
share the facilities. Therefore, the rseq field should include the
nesting counter as part of the RSEQ ABI so various userspace libraries
can use it collaboratively.
Thanks,
Mathieu
--
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com
