[src/trunk]: src/sys/external/bsd/common/linux Fix membars in tasklet_disable...

[riastradh <riastradh%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/4fc8e7a5a1c7
branches:  trunk
changeset: 1028451:4fc8e7a5a1c7
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Sun Dec 19 11:04:58 2021 +0000

description:
Fix membars in tasklet_disable/enable.

diffstat:

 sys/external/bsd/common/linux/linux_tasklet.c |  35 ++++++++++++++++++++------
 1 files changed, 27 insertions(+), 8 deletions(-)

diffs (96 lines):

diff -r 1c3a5787ee42 -r 4fc8e7a5a1c7 sys/external/bsd/common/linux/linux_tasklet.c
--- a/sys/external/bsd/common/linux/linux_tasklet.c     Sun Dec 19 11:04:50 2021 +0000
+++ b/sys/external/bsd/common/linux/linux_tasklet.c     Sun Dec 19 11:04:58 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: linux_tasklet.c,v 1.5 2021/12/19 11:03:18 riastradh Exp $      */
+/*     $NetBSD: linux_tasklet.c,v 1.6 2021/12/19 11:04:58 riastradh Exp $      */
 
 /*-
  * Copyright (c) 2018, 2020 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: linux_tasklet.c,v 1.5 2021/12/19 11:03:18 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: linux_tasklet.c,v 1.6 2021/12/19 11:04:58 riastradh Exp $");
 
 #include <sys/types.h>
 #include <sys/atomic.h>
@@ -373,6 +373,11 @@
        KASSERT(disablecount < UINT_MAX);
        KASSERT(disablecount != 0);
 
+       /* Pairs with membar_exit in __tasklet_enable.  */
+#ifndef __HAVE_ATOMIC_AS_MEMBAR
+       membar_enter();
+#endif
+
        /* Wait for it to finish running, if it was running.  */
        tasklet_unlock_wait(tasklet);
 }
@@ -457,13 +462,17 @@
        unsigned state;
 
        do {
-               /* Pairs with membar_exit in tasklet_unlock.  */
-               state = atomic_load_acquire(&tasklet->tl_state);
+               state = atomic_load_relaxed(&tasklet->tl_state);
                if (state & TASKLET_RUNNING)
                        return false;
        } while (atomic_cas_uint(&tasklet->tl_state, state,
                state | TASKLET_RUNNING) != state);
 
+       /* Pairs with membar_exit in tasklet_unlock.  */
+#ifndef __HAVE_ATOMIC_AS_MEMBAR
+       membar_enter();
+#endif
+
        return true;
 }
 
@@ -481,8 +490,8 @@
        KASSERT(atomic_load_relaxed(&tasklet->tl_state) & TASKLET_RUNNING);
 
        /*
-        * Pairs with atomic_load_acquire in tasklet_trylock and
-        * tasklet_unlock.
+        * Pairs with membar_enter in tasklet_trylock and with
+        * atomic_load_acquire in tasklet_unlock_wait.
         */
 #ifndef __HAVE_ATOMIC_AS_MEMBAR
        membar_exit();
@@ -534,6 +543,11 @@
        KASSERT(disablecount < UINT_MAX);
        KASSERT(disablecount != 0);
 
+       /* Pairs with membar_exit in __tasklet_enable_sync_once.  */
+#ifndef __HAVE_ATOMIC_AS_MEMBAR
+       membar_enter();
+#endif
+
        /*
         * If it was zero, wait for it to finish running.  If it was
         * not zero, caller must not care whether it was running.
@@ -553,6 +567,11 @@
 {
        unsigned int disablecount;
 
+       /* Pairs with membar_enter in __tasklet_disable_sync_once.  */
+#ifndef __HAVE_ATOMIC_AS_MEMBAR
+       membar_exit();
+#endif
+
        /* Decrement the disable count.  */
        disablecount = atomic_dec_uint_nv(&tasklet->tl_disablecount);
        KASSERT(disablecount < UINT_MAX);
@@ -615,8 +634,8 @@
         * before potentially allowing tasklet to run again by
         * decrementing the disable count.
         *
-        * Pairs with atomic_load_acquire(&tasklet->tl_disablecount) in
-        * tasklet_softintr.
+        * Pairs with atomic_load_acquire in tasklet_softintr and with
+        * membar_enter in tasklet_disable.
         */
 #ifndef __HAVE_ATOMIC_AS_MEMBAR
        membar_exit();