From ecbd8047526d3e9681043c287dea7bc67ef33eb4 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Sat, 15 Mar 2025 21:05:30 -0700 Subject: rqspinlock: Add basic support for CONFIG_PARAVIRT We ripped out PV and virtualization related bits from rqspinlock in an earlier commit, however, a fair lock performs poorly within a virtual machine when the lock holder is preempted. As such, retain the virt_spin_lock fallback to test and set lock, but with timeout and deadlock detection. We can do this by simply depending on the resilient_tas_spin_lock implementation from the previous patch. We don't integrate support for CONFIG_PARAVIRT_SPINLOCKS yet, as that requires more involved algorithmic changes and introduces more complexity. It can be done when the need arises in the future. Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20250316040541.108729-15-memxor@gmail.com Signed-off-by: Alexei Starovoitov --- include/asm-generic/rqspinlock.h | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'include') diff --git a/include/asm-generic/rqspinlock.h b/include/asm-generic/rqspinlock.h index 12f72c4a97cd..a837c6b6abd9 100644 --- a/include/asm-generic/rqspinlock.h +++ b/include/asm-generic/rqspinlock.h @@ -35,6 +35,20 @@ extern int resilient_tas_spin_lock(rqspinlock_t *lock); extern int resilient_queued_spin_lock_slowpath(rqspinlock_t *lock, u32 val); #endif +#ifndef resilient_virt_spin_lock_enabled +static __always_inline bool resilient_virt_spin_lock_enabled(void) +{ + return false; +} +#endif + +#ifndef resilient_virt_spin_lock +static __always_inline int resilient_virt_spin_lock(rqspinlock_t *lock) +{ + return 0; +} +#endif + /* * Default timeout for waiting loops is 0.25 seconds */ -- cgit v1.2.3