Let futex_wait() run without kernel lock

The KERNEL_LOCK() is no longer necessary with rwsleep() and PCATCH
because the sleep machinery now does the locking internally.

OK mpi@

diff --git a/sys/kern/sys_futex.c b/sys/kern/sys_futex.c
index 1cd3e71..b9303a9 100644 (file)
--- a/sys/kern/sys_futex.c
+++ b/sys/kern/sys_futex.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: sys_futex.c,v 1.19 2021/11/19 15:58:36 kettenis Exp $ */
+/*     $OpenBSD: sys_futex.c,v 1.20 2021/11/22 14:57:17 visa Exp $ */
 
 /*
  * Copyright (c) 2016-2017 Martin Pieuchot
@@ -104,31 +104,25 @@ sys_futex(struct proc *p, void *v, register_t *retval)
        if (op & FUTEX_PRIVATE_FLAG)
                flags |= FT_PRIVATE;
 
+       rw_enter_write(&ftlock);
        switch (op) {
        case FUTEX_WAIT:
        case FUTEX_WAIT_PRIVATE:
-               KERNEL_LOCK();
-               rw_enter_write(&ftlock);
                error = futex_wait(uaddr, val, timeout, flags);
-               rw_exit_write(&ftlock);
-               KERNEL_UNLOCK();
                break;
        case FUTEX_WAKE:
        case FUTEX_WAKE_PRIVATE:
-               rw_enter_write(&ftlock);
                *retval = futex_wake(uaddr, val, flags);
-               rw_exit_write(&ftlock);
                break;
        case FUTEX_REQUEUE:
        case FUTEX_REQUEUE_PRIVATE:
-               rw_enter_write(&ftlock);
                *retval = futex_requeue(uaddr, val, g, (u_long)timeout, flags);
-               rw_exit_write(&ftlock);
                break;
        default:
                error = ENOSYS;
                break;
        }
+       rw_exit_write(&ftlock);
 
        return error;
 }