Commit f510b233 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

lockdep: get_user_chars() redo 



Generic, states independent, get_user_chars().

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 3ff176ca

Documentation/lockdep-design.txt

+17 −13
Original line number Diff line number Diff line
@@ -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

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.

kernel/lockdep.c

+12 −12
Original line number Diff line number Diff line
@@ -487,25 +487,25 @@ static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit) 
	return c;

}



void

get_usage_chars(struct lock_class *class, char *c1, char *c2, char *c3,

					char *c4, char *c5, char *c6)

void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])

{

	*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);

	int i = 0;



	*c5 = get_usage_char(class, LOCK_USED_IN_RECLAIM_FS);

	*c6 = get_usage_char(class, LOCK_USED_IN_RECLAIM_FS_READ);

#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



	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_class *class) 
		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)

kernel/lockdep_internals.h

+4 −3
Original line number Diff line number Diff line
@@ -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);

kernel/lockdep_proc.c

+3 −3
Original line number Diff line number Diff line
@@ -84,7 +84,7 @@ static int l_show(struct seq_file *m, void *v) 
{

	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, void *v) 
	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);