On Fri, Jan 31, 2025 at 05:58:38PM -0500, Steven Rostedt wrote: > From: "Steven Rostedt (Google)" <rostedt@xxxxxxxxxxx> > > This is to improve user space implemented spin locks or any critical > section. It may also be extended for VMs and their guest spin locks as > well, but that will come later. > > This adds a new field in the struct rseq called cr_counter. This is a 32 bit > field where bit zero is a flag reserved for the kernel, and the other 31 > bits can be used as a counter (although the kernel doesn't care how they > are used, as any bit set means the same). > > This works in tandem with PREEMPT_LAZY, where a task can tell the kernel > via the rseq structure that it is in a critical section (like holding a > spin lock) that it will be leaving very shortly, and to ask the kernel to > not preempt it at the moment. I still have full hate for this approach.
