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Subject[PATCH 20/21] lockdep: get_user_chars() redo
Generic, states independent, get_user_chars().

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
Documentation/lockdep-design.txt | 30 +++++++++++++++++-------------
kernel/lockdep.c | 26 +++++++++++++-------------
kernel/lockdep_internals.h | 7 ++++---
kernel/lockdep_proc.c | 6 +++---
4 files changed, 37 insertions(+), 32 deletions(-)
Index: linux-2.6/kernel/lockdep.c
===================================================================
--- linux-2.6.orig/kernel/lockdep.c
+++ linux-2.6/kernel/lockdep.c
@@ -487,25 +487,25 @@ static char get_usage_char(struct lock_c
return c;
}

-void
-get_usage_chars(struct lock_class *class, char *c1, char *c2, char *c3,
- char *c4, char *c5, char *c6)
-{
- *c1 = get_usage_char(class, LOCK_USED_IN_HARDIRQ);
- *c2 = get_usage_char(class, LOCK_USED_IN_SOFTITQ);
- *c3 = get_usage_char(class, LOCK_USED_IN_HARDIRQ_READ);
- *c4 = get_usage_char(class, LOCK_USED_IN_SOFTITQ_READ);
+void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
+{
+ int i = 0;
+
+#define LOCKDEP_STATE(__STATE) \
+ usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
+ usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
+#include "lockdep_states.h"
+#undef LOCKDEP_STATE

- *c5 = get_usage_char(class, LOCK_USED_IN_RECLAIM_FS);
- *c6 = get_usage_char(class, LOCK_USED_IN_RECLAIM_FS_READ);
+ usage[i] = '\0';
}

static void print_lock_name(struct lock_class *class)
{
- char str[KSYM_NAME_LEN], c1, c2, c3, c4, c5, c6;
+ char str[KSYM_NAME_LEN], usage[LOCK_USAGE_CHARS];
const char *name;

- get_usage_chars(class, &c1, &c2, &c3, &c4, &c5, &c6);
+ get_usage_chars(class, usage);

name = class->name;
if (!name) {
@@ -518,7 +518,7 @@ static void print_lock_name(struct lock_
if (class->subclass)
printk("/%d", class->subclass);
}
- printk("){%c%c%c%c%c%c}", c1, c2, c3, c4, c5, c6);
+ printk("){%s}", usage);
}

static void print_lockdep_cache(struct lockdep_map *lock)
Index: linux-2.6/kernel/lockdep_internals.h
===================================================================
--- linux-2.6.orig/kernel/lockdep_internals.h
+++ linux-2.6/kernel/lockdep_internals.h
@@ -70,9 +70,10 @@ enum {
extern struct list_head all_lock_classes;
extern struct lock_chain lock_chains[];

-extern void
-get_usage_chars(struct lock_class *class, char *c1, char *c2, char *c3,
- char *c4, char *c5, char *c6);
+#define LOCK_USAGE_CHARS (1+LOCK_USAGE_STATES/2)
+
+extern void get_usage_chars(struct lock_class *class,
+ char usage[LOCK_USAGE_CHARS]);

extern const char * __get_key_name(struct lockdep_subclass_key *key, char *str);

Index: linux-2.6/kernel/lockdep_proc.c
===================================================================
--- linux-2.6.orig/kernel/lockdep_proc.c
+++ linux-2.6/kernel/lockdep_proc.c
@@ -84,7 +84,7 @@ static int l_show(struct seq_file *m, vo
{
struct lock_class *class = v;
struct lock_list *entry;
- char c1, c2, c3, c4, c5, c6;
+ char usage[LOCK_USAGE_CHARS];

if (v == SEQ_START_TOKEN) {
seq_printf(m, "all lock classes:\n");
@@ -100,8 +100,8 @@ static int l_show(struct seq_file *m, vo
seq_printf(m, " BD:%5ld", lockdep_count_backward_deps(class));
#endif

- get_usage_chars(class, &c1, &c2, &c3, &c4, &c5, &c6);
- seq_printf(m, " %c%c%c%c%c%c", c1, c2, c3, c4, c5, c6);
+ get_usage_chars(class, usage);
+ seq_printf(m, " %s", usage);

seq_printf(m, ": ");
print_name(m, class);
Index: linux-2.6/Documentation/lockdep-design.txt
===================================================================
--- linux-2.6.orig/Documentation/lockdep-design.txt
+++ linux-2.6/Documentation/lockdep-design.txt
@@ -27,33 +27,37 @@ lock-class.
State
-----

-The validator tracks lock-class usage history into 5 separate state bits:
+The validator tracks lock-class usage history into 4n + 1 separate state bits:

-- 'ever held in hardirq context' [ == hardirq-safe ]
-- 'ever held in softirq context' [ == softirq-safe ]
-- 'ever held with hardirqs enabled' [ == hardirq-unsafe ]
-- 'ever held with softirqs and hardirqs enabled' [ == softirq-unsafe ]
+- 'ever held in STATE context'
+- 'ever head as readlock in STATE context'
+- 'ever head with STATE enabled'
+- 'ever head as readlock with STATE enabled'
+
+Where STATE can be either one of (kernel/lockdep_states.h)
+ - hardirq
+ - softirq
+ - reclaim_fs

- 'ever used' [ == !unused ]

-When locking rules are violated, these 4 state bits are presented in the
-locking error messages, inside curlies. A contrived example:
+When locking rules are violated, these state bits are presented in the
+locking error messages, inside curlies. A contrived example:

modprobe/2287 is trying to acquire lock:
- (&sio_locks[i].lock){--..}, at: [<c02867fd>] mutex_lock+0x21/0x24
+ (&sio_locks[i].lock){-.-...}, at: [<c02867fd>] mutex_lock+0x21/0x24

but task is already holding lock:
- (&sio_locks[i].lock){--..}, at: [<c02867fd>] mutex_lock+0x21/0x24
+ (&sio_locks[i].lock){-.-...}, at: [<c02867fd>] mutex_lock+0x21/0x24


-The bit position indicates hardirq, softirq, hardirq-read,
-softirq-read respectively, and the character displayed in each
-indicates:
+The bit position indicates STATE, STATE-read, for each of the states listed
+above, and the character displayed in each indicates:

'.' acquired while irqs disabled
'+' acquired in irq context
'-' acquired with irqs enabled
- '?' read acquired in irq context with irqs enabled.
+ '?' acquired in irq context with irqs enabled.

Unused mutexes cannot be part of the cause of an error.

--



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