Author: attilio
Date: Mon Sep 7 08:37:25 2009
New Revision: 196912
URL: http://svn.freebsd.org/changeset/base/196912
Log:
MFC r196334:
Add the macro ASSERT_ATOMIC_LOAD_PTR(), enabled through INVARIANTS,
which asserts for the correct alignment of datas which need to be read
atomically without locks.
Use that macro in locking primitives.
Modified:
stable/7/sys/kern/kern_mutex.c
stable/7/sys/kern/kern_rwlock.c
stable/7/sys/kern/kern_sx.c
stable/7/sys/sys/systm.h
Modified: stable/7/sys/kern/kern_mutex.c
==============================================================================
--- stable/7/sys/kern/kern_mutex.c Mon Sep 7 06:37:44 2009
(r196911)
+++ stable/7/sys/kern/kern_mutex.c Mon Sep 7 08:37:25 2009
(r196912)
@@ -724,6 +724,9 @@ mtx_init(struct mtx *m, const char *name
MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE |
MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE)) == 0);
+ ASSERT_ATOMIC_LOAD_PTR(m->mtx_lock,
+ ("%s: mtx_lock not aligned for %s:%p", __func__, name,
+ &m->mtx_lock));
#ifdef MUTEX_DEBUG
/* Diagnostic and error correction */
Modified: stable/7/sys/kern/kern_rwlock.c
==============================================================================
--- stable/7/sys/kern/kern_rwlock.c Mon Sep 7 06:37:44 2009
(r196911)
+++ stable/7/sys/kern/kern_rwlock.c Mon Sep 7 08:37:25 2009
(r196912)
@@ -137,6 +137,9 @@ rw_init_flags(struct rwlock *rw, const c
MPASS((opts & ~(RW_DUPOK | RW_NOPROFILE | RW_NOWITNESS | RW_QUIET |
RW_RECURSE)) == 0);
+ ASSERT_ATOMIC_LOAD_PTR(rw->rw_lock,
+ ("%s: rw_lock not aligned for %s:%p", __func__, name,
+ &rw->rw_lock));
flags = LO_UPGRADABLE | LO_RECURSABLE;
if (opts & RW_DUPOK)
Modified: stable/7/sys/kern/kern_sx.c
==============================================================================
--- stable/7/sys/kern/kern_sx.c Mon Sep 7 06:37:44 2009 (r196911)
+++ stable/7/sys/kern/kern_sx.c Mon Sep 7 08:37:25 2009 (r196912)
@@ -166,6 +166,9 @@ sx_init_flags(struct sx *sx, const char
MPASS((opts & ~(SX_QUIET | SX_RECURSE | SX_NOWITNESS | SX_DUPOK |
SX_NOPROFILE | SX_ADAPTIVESPIN)) == 0);
+ ASSERT_ATOMIC_LOAD_PTR(sx->sx_lock,
+ ("%s: sx_lock not aligned for %s:%p", __func__, description,
+ &sx->sx_lock));
flags = LO_RECURSABLE | LO_SLEEPABLE | LO_UPGRADABLE;
if (opts & SX_DUPOK)
Modified: stable/7/sys/sys/systm.h
==============================================================================
--- stable/7/sys/sys/systm.h Mon Sep 7 06:37:44 2009 (r196911)
+++ stable/7/sys/sys/systm.h Mon Sep 7 08:37:25 2009 (r196912)
@@ -96,6 +96,17 @@ extern int maxusers; /* system tune hin
#endif
/*
+ * Assert that a pointer can be loaded from memory atomically.
+ *
+ * This assertion enforces stronger alignment than necessary. For example,
+ * on some architectures, atomicity for unaligned loads will depend on
+ * whether or not the load spans multiple cache lines.
+ */
+#define ASSERT_ATOMIC_LOAD_PTR(var, msg)
\
+ KASSERT(sizeof(var) == sizeof(void *) && \
+ ((uintptr_t)&(var) & (sizeof(void *) - 1)) == 0, msg)
+
+/*
* XXX the hints declarations are even more misplaced than most declarations
* in this file, since they are needed in one file (per arch) and only used
* in two files.
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