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Subject[PATCH 21/21] lockdep: simplify check_prev_add_irq()
Remove the manual state iteration thingy.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
kernel/lockdep.c | 154 +++++++++++++++++++++----------------------------------
1 file changed, 61 insertions(+), 93 deletions(-)
Index: linux-2.6/kernel/lockdep.c
===================================================================
--- linux-2.6.orig/kernel/lockdep.c
+++ linux-2.6/kernel/lockdep.c
@@ -1268,68 +1268,84 @@ check_usage(struct task_struct *curr, st
bit_backwards, bit_forwards, irqclass);
}

-static int
-check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
- struct held_lock *next)
+static const char *state_names[] = {
+#define LOCKDEP_STATE(__STATE) \
+ STR(__STATE),
+#include "lockdep_states.h"
+#undef LOCKDEP_STATE
+};
+
+static const char *state_rnames[] = {
+#define LOCKDEP_STATE(__STATE) \
+ STR(__STATE)"-READ",
+#include "lockdep_states.h"
+#undef LOCKDEP_STATE
+};
+
+static inline const char *state_name(enum lock_usage_bit bit)
{
- /*
- * Prove that the new dependency does not connect a hardirq-safe
- * lock with a hardirq-unsafe lock - to achieve this we search
- * the backwards-subgraph starting at <prev>, and the
- * forwards-subgraph starting at <next>:
- */
- if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ,
- LOCK_ENABLED_HARDIRQ, "hard"))
- return 0;
+ return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
+}

+static int exclusive_bit(int new_bit)
+{
/*
- * Prove that the new dependency does not connect a hardirq-safe-read
- * lock with a hardirq-unsafe lock - to achieve this we search
- * the backwards-subgraph starting at <prev>, and the
- * forwards-subgraph starting at <next>:
+ * USED_IN
+ * USED_IN_READ
+ * ENABLED
+ * ENABLED_READ
+ *
+ * bit 0 - write/read
+ * bit 1 - used_in/enabled
+ * bit 2+ state
*/
- if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ_READ,
- LOCK_ENABLED_HARDIRQ, "hard-read"))
- return 0;
+
+ int state = new_bit & ~3;
+ int dir = new_bit & 2;

/*
- * Prove that the new dependency does not connect a softirq-safe
- * lock with a softirq-unsafe lock - to achieve this we search
- * the backwards-subgraph starting at <prev>, and the
- * forwards-subgraph starting at <next>:
+ * keep state, bit flip the direction and strip read.
*/
- if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ,
- LOCK_ENABLED_SOFTIRQ, "soft"))
- return 0;
+ return state | (dir ^ 2);
+}
+
+static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
+ struct held_lock *next, enum lock_usage_bit bit)
+{
/*
- * Prove that the new dependency does not connect a softirq-safe-read
- * lock with a softirq-unsafe lock - to achieve this we search
+ * Prove that the new dependency does not connect a hardirq-safe
+ * lock with a hardirq-unsafe lock - to achieve this we search
* the backwards-subgraph starting at <prev>, and the
* forwards-subgraph starting at <next>:
*/
- if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ_READ,
- LOCK_ENABLED_SOFTIRQ, "soft"))
+ if (!check_usage(curr, prev, next, bit,
+ exclusive_bit(bit), state_name(bit)))
return 0;

+ bit++; /* _READ */
+
/*
- * Prove that the new dependency does not connect a reclaim-fs-safe
- * lock with a reclaim-fs-unsafe lock - to achieve this we search
+ * Prove that the new dependency does not connect a hardirq-safe-read
+ * lock with a hardirq-unsafe lock - to achieve this we search
* the backwards-subgraph starting at <prev>, and the
* forwards-subgraph starting at <next>:
*/
- if (!check_usage(curr, prev, next, LOCK_USED_IN_RECLAIM_FS,
- LOCK_ENABLED_RECLAIM_FS, "reclaim-fs"))
+ if (!check_usage(curr, prev, next, bit,
+ exclusive_bit(bit), state_name(bit)))
return 0;

- /*
- * Prove that the new dependency does not connect a reclaim-fs-safe-read
- * lock with a reclaim-fs-unsafe lock - to achieve this we search
- * the backwards-subgraph starting at <prev>, and the
- * forwards-subgraph starting at <next>:
- */
- if (!check_usage(curr, prev, next, LOCK_USED_IN_RECLAIM_FS_READ,
- LOCK_ENABLED_RECLAIM_FS, "reclaim-fs-read"))
+ return 1;
+}
+
+static int
+check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
+ struct held_lock *next)
+{
+#define LOCKDEP_STATE(__STATE) \
+ if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
return 0;
+#include "lockdep_states.h"
+#undef LOCKDEP_STATE

return 1;
}
@@ -1984,30 +2000,6 @@ static int RECLAIM_FS_verbose(struct loc

#define STRICT_READ_CHECKS 1

-static const char *state_names[] = {
-#define LOCKDEP_STATE(__STATE) \
- STR(__STATE),
-#include "lockdep_states.h"
-#undef LOCKDEP_STATE
-};
-
-static inline const char *state_name(enum lock_usage_bit bit)
-{
- return state_names[bit >> 2];
-}
-
-static const char *state_rnames[] = {
-#define LOCKDEP_STATE(__STATE) \
- STR(__STATE)"-READ",
-#include "lockdep_states.h"
-#undef LOCKDEP_STATE
-};
-
-static inline const char *state_rname(enum lock_usage_bit bit)
-{
- return state_rnames[bit >> 2];
-}
-
static int (*state_verbose_f[])(struct lock_class *class) = {
#define LOCKDEP_STATE(__STATE) \
__STATE##_verbose,
@@ -2021,37 +2013,12 @@ static inline int state_verbose(enum loc
return state_verbose_f[bit >> 2](class);
}

-static int exclusive_bit(int new_bit)
-{
- /*
- * USED_IN
- * USED_IN_READ
- * ENABLED
- * ENABLED_READ
- *
- * bit 0 - write/read
- * bit 1 - used_in/enabled
- * bit 2+ state
- */
-
- int state = new_bit & ~3;
- int dir = new_bit & 2;
-
- /*
- * keep state, bit flip the direction and strip read.
- */
- return state | (dir ^ 2);
-}
-
typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
enum lock_usage_bit bit, const char *name);

static int
mark_lock_irq(struct task_struct *curr, struct held_lock *this, int new_bit)
{
- const char *name = state_name(new_bit);
- const char *rname = state_rname(new_bit);
-
int excl_bit = exclusive_bit(new_bit);
int read = new_bit & 1;
int dir = new_bit & 2;
@@ -2078,7 +2045,7 @@ mark_lock_irq(struct task_struct *curr,
* states.
*/
if ((!read || !dir || STRICT_READ_CHECKS) &&
- !usage(curr, this, excl_bit, name))
+ !usage(curr, this, excl_bit, state_name(new_bit)))
return 0;

/*
@@ -2089,7 +2056,8 @@ mark_lock_irq(struct task_struct *curr,
return 0;

if (STRICT_READ_CHECKS &&
- !usage(curr, this, excl_bit + 1, rname))
+ !usage(curr, this, excl_bit + 1,
+ state_name(new_bit + 1)))
return 0;
}

--



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