Author: thompsa
Date: Wed Jan 21 04:19:18 2009
New Revision: 187511
URL: http://svn.freebsd.org/changeset/base/187511
Log:
Add functions WITNESS so it can be asserted that the lock is not released for
a
section of code, this uses WITNESS_NORELEASE() and WITNESS_RELEASEOK() to mark
the boundaries. Both functions require the lock to be held when calling.
This is intended for scenarios like a bus asserting that the bus lock is not
dropped during a driver call. There doesn't appear to be a man page to
document this in.
Reviewed by: jhb
Modified:
head/sys/kern/subr_witness.c
head/sys/sys/lock.h
Modified: head/sys/kern/subr_witness.c
==============================================================================
--- head/sys/kern/subr_witness.c Wed Jan 21 02:53:00 2009
(r187510)
+++ head/sys/kern/subr_witness.c Wed Jan 21 04:19:18 2009
(r187511)
@@ -127,6 +127,7 @@ __FBSDID("$FreeBSD$");
#define LI_RECURSEMASK 0x0000ffff /* Recursion depth of lock
instance. */
#define LI_EXCLUSIVE 0x00010000 /* Exclusive lock instance. */
+#define LI_NORELEASE 0x00020000 /* Lock not allowed to be
released. */
/* Define this to check for blessed mutexes */
#undef BLESSING
@@ -367,6 +368,7 @@ static struct witness_lock_order_data *w
struct witness *parent,
struct witness *child);
static void witness_list_lock(struct lock_instance *instance);
+static void witness_setflag(struct lock_object *lock, int flag, int set);
#ifdef KDB
#define witness_debugger(c) _witness_debugger(c, __func__)
@@ -1509,6 +1511,11 @@ found:
instance->li_line);
panic("share->uexcl");
}
+ if ((instance->li_flags & LI_NORELEASE) != 0 && witness_watch > 0) {
+ printf("forbidden unlock of (%s) %s @ %s:%d\n", class->lc_name,
+ lock->lo_name, file, line);
+ panic("lock marked norelease");
+ }
/* If we are recursed, unrecurse. */
if ((instance->li_flags & LI_RECURSEMASK) > 0) {
@@ -2224,6 +2231,48 @@ witness_assert(struct lock_object *lock,
#endif /* INVARIANT_SUPPORT */
}
+static void
+witness_setflag(struct lock_object *lock, int flag, int set)
+{
+ struct lock_list_entry *lock_list;
+ struct lock_instance *instance;
+ struct lock_class *class;
+
+ if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL)
+ return;
+ class = LOCK_CLASS(lock);
+ if (class->lc_flags & LC_SLEEPLOCK)
+ lock_list = curthread->td_sleeplocks;
+ else {
+ if (witness_skipspin)
+ return;
+ lock_list = PCPU_GET(spinlocks);
+ }
+ instance = find_instance(lock_list, lock);
+ if (instance == NULL)
+ panic("%s: lock (%s) %s not locked", __func__,
+ class->lc_name, lock->lo_name);
+
+ if (set)
+ instance->li_flags |= flag;
+ else
+ instance->li_flags &= ~flag;
+}
+
+void
+witness_norelease(struct lock_object *lock)
+{
+
+ witness_setflag(lock, LI_NORELEASE, 1);
+}
+
+void
+witness_releaseok(struct lock_object *lock)
+{
+
+ witness_setflag(lock, LI_NORELEASE, 0);
+}
+
#ifdef DDB
static void
witness_ddb_list(struct thread *td)
Modified: head/sys/sys/lock.h
==============================================================================
--- head/sys/sys/lock.h Wed Jan 21 02:53:00 2009 (r187510)
+++ head/sys/sys/lock.h Wed Jan 21 04:19:18 2009 (r187511)
@@ -216,6 +216,8 @@ int witness_warn(int, struct lock_object
void witness_assert(struct lock_object *, int, const char *, int);
void witness_display_spinlock(struct lock_object *, struct thread *);
int witness_line(struct lock_object *);
+void witness_norelease(struct lock_object *);
+void witness_releaseok(struct lock_object *);
const char *witness_file(struct lock_object *);
void witness_thread_exit(struct thread *);
@@ -267,6 +269,12 @@ void witness_thread_exit(struct thread *
#define WITNESS_RESTORE(lock, n)
\
witness_restore((lock), __CONCAT(n, __wf), __CONCAT(n, __wl))
+#define WITNESS_NORELEASE(lock)
\
+ witness_norelease(&(lock)->lock_object)
+
+#define WITNESS_RELEASEOK(lock)
\
+ witness_releaseok(&(lock)->lock_object)
+
#define WITNESS_FILE(lock)
\
witness_file(lock)
@@ -287,6 +295,8 @@ void witness_thread_exit(struct thread *
#define WITNESS_SAVE_DECL(n)
#define WITNESS_SAVE(lock, n)
#define WITNESS_RESTORE(lock, n)
+#define WITNESS_NORELEASE(lock)
+#define WITNESS_RELEASEOK(lock)
#define WITNESS_FILE(lock) ("?")
#define WITNESS_LINE(lock) (0)
#endif /* WITNESS */
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