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-rw-r--r--kernel/locking/lockdep.c267
1 files changed, 183 insertions, 84 deletions
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 91c6b89f04df..27b992fe8cec 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -501,11 +501,11 @@ static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
{
char c = '.';
- if (class->usage_mask & lock_flag(bit + 2))
+ if (class->usage_mask & lock_flag(bit + LOCK_USAGE_DIR_MASK))
c = '+';
if (class->usage_mask & lock_flag(bit)) {
c = '-';
- if (class->usage_mask & lock_flag(bit + 2))
+ if (class->usage_mask & lock_flag(bit + LOCK_USAGE_DIR_MASK))
c = '?';
}
@@ -1666,19 +1666,25 @@ check_redundant(struct lock_list *root, struct lock_class *target,
}
#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
+
+static inline int usage_accumulate(struct lock_list *entry, void *mask)
+{
+ *(unsigned long *)mask |= entry->class->usage_mask;
+
+ return 0;
+}
+
/*
* Forwards and backwards subgraph searching, for the purposes of
* proving that two subgraphs can be connected by a new dependency
* without creating any illegal irq-safe -> irq-unsafe lock dependency.
*/
-static inline int usage_match(struct lock_list *entry, void *bit)
+static inline int usage_match(struct lock_list *entry, void *mask)
{
- return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
+ return entry->class->usage_mask & *(unsigned long *)mask;
}
-
-
/*
* Find a node in the forwards-direction dependency sub-graph starting
* at @root->class that matches @bit.
@@ -1690,14 +1696,14 @@ static inline int usage_match(struct lock_list *entry, void *bit)
* Return <0 on error.
*/
static int
-find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
+find_usage_forwards(struct lock_list *root, unsigned long usage_mask,
struct lock_list **target_entry)
{
int result;
debug_atomic_inc(nr_find_usage_forwards_checks);
- result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
+ result = __bfs_forwards(root, &usage_mask, usage_match, target_entry);
return result;
}
@@ -1713,14 +1719,14 @@ find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
* Return <0 on error.
*/
static int
-find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
+find_usage_backwards(struct lock_list *root, unsigned long usage_mask,
struct lock_list **target_entry)
{
int result;
debug_atomic_inc(nr_find_usage_backwards_checks);
- result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
+ result = __bfs_backwards(root, &usage_mask, usage_match, target_entry);
return result;
}
@@ -1912,39 +1918,6 @@ print_bad_irq_dependency(struct task_struct *curr,
return 0;
}
-static int
-check_usage(struct task_struct *curr, struct held_lock *prev,
- struct held_lock *next, enum lock_usage_bit bit_backwards,
- enum lock_usage_bit bit_forwards, const char *irqclass)
-{
- int ret;
- struct lock_list this, that;
- struct lock_list *uninitialized_var(target_entry);
- struct lock_list *uninitialized_var(target_entry1);
-
- this.parent = NULL;
-
- this.class = hlock_class(prev);
- ret = find_usage_backwards(&this, bit_backwards, &target_entry);
- if (ret < 0)
- return print_bfs_bug(ret);
- if (ret == 1)
- return ret;
-
- that.parent = NULL;
- that.class = hlock_class(next);
- ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
- if (ret < 0)
- return print_bfs_bug(ret);
- if (ret == 1)
- return ret;
-
- return print_bad_irq_dependency(curr, &this, &that,
- target_entry, target_entry1,
- prev, next,
- bit_backwards, bit_forwards, irqclass);
-}
-
static const char *state_names[] = {
#define LOCKDEP_STATE(__STATE) \
__stringify(__STATE),
@@ -1961,9 +1934,19 @@ static const char *state_rnames[] = {
static inline const char *state_name(enum lock_usage_bit bit)
{
- return (bit & LOCK_USAGE_READ_MASK) ? state_rnames[bit >> 2] : state_names[bit >> 2];
+ if (bit & LOCK_USAGE_READ_MASK)
+ return state_rnames[bit >> LOCK_USAGE_DIR_MASK];
+ else
+ return state_names[bit >> LOCK_USAGE_DIR_MASK];
}
+/*
+ * The bit number is encoded like:
+ *
+ * bit0: 0 exclusive, 1 read lock
+ * bit1: 0 used in irq, 1 irq enabled
+ * bit2-n: state
+ */
static int exclusive_bit(int new_bit)
{
int state = new_bit & LOCK_USAGE_STATE_MASK;
@@ -1975,45 +1958,160 @@ static int exclusive_bit(int new_bit)
return state | (dir ^ LOCK_USAGE_DIR_MASK);
}
+/*
+ * Observe that when given a bitmask where each bitnr is encoded as above, a
+ * right shift of the mask transforms the individual bitnrs as -1 and
+ * conversely, a left shift transforms into +1 for the individual bitnrs.
+ *
+ * So for all bits whose number have LOCK_ENABLED_* set (bitnr1 == 1), we can
+ * create the mask with those bit numbers using LOCK_USED_IN_* (bitnr1 == 0)
+ * instead by subtracting the bit number by 2, or shifting the mask right by 2.
+ *
+ * Similarly, bitnr1 == 0 becomes bitnr1 == 1 by adding 2, or shifting left 2.
+ *
+ * So split the mask (note that LOCKF_ENABLED_IRQ_ALL|LOCKF_USED_IN_IRQ_ALL is
+ * all bits set) and recompose with bitnr1 flipped.
+ */
+static unsigned long invert_dir_mask(unsigned long mask)
+{
+ unsigned long excl = 0;
+
+ /* Invert dir */
+ excl |= (mask & LOCKF_ENABLED_IRQ_ALL) >> LOCK_USAGE_DIR_MASK;
+ excl |= (mask & LOCKF_USED_IN_IRQ_ALL) << LOCK_USAGE_DIR_MASK;
+
+ return excl;
+}
+
+/*
+ * As above, we clear bitnr0 (LOCK_*_READ off) with bitmask ops. First, for all
+ * bits with bitnr0 set (LOCK_*_READ), add those with bitnr0 cleared (LOCK_*).
+ * And then mask out all bitnr0.
+ */
+static unsigned long exclusive_mask(unsigned long mask)
+{
+ unsigned long excl = invert_dir_mask(mask);
+
+ /* Strip read */
+ excl |= (excl & LOCKF_IRQ_READ) >> LOCK_USAGE_READ_MASK;
+ excl &= ~LOCKF_IRQ_READ;
+
+ return excl;
+}
+
+/*
+ * Retrieve the _possible_ original mask to which @mask is
+ * exclusive. Ie: this is the opposite of exclusive_mask().
+ * Note that 2 possible original bits can match an exclusive
+ * bit: one has LOCK_USAGE_READ_MASK set, the other has it
+ * cleared. So both are returned for each exclusive bit.
+ */
+static unsigned long original_mask(unsigned long mask)
+{
+ unsigned long excl = invert_dir_mask(mask);
+
+ /* Include read in existing usages */
+ excl |= (excl & LOCKF_IRQ) << LOCK_USAGE_READ_MASK;
+
+ return excl;
+}
+
+/*
+ * Find the first pair of bit match between an original
+ * usage mask and an exclusive usage mask.
+ */
+static int find_exclusive_match(unsigned long mask,
+ unsigned long excl_mask,
+ enum lock_usage_bit *bitp,
+ enum lock_usage_bit *excl_bitp)
+{
+ int bit, excl;
+
+ for_each_set_bit(bit, &mask, LOCK_USED) {
+ excl = exclusive_bit(bit);
+ if (excl_mask & lock_flag(excl)) {
+ *bitp = bit;
+ *excl_bitp = excl;
+ return 0;
+ }
+ }
+ return -1;
+}
+
+/*
+ * 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>:
+ */
static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
- struct held_lock *next, enum lock_usage_bit bit)
+ struct held_lock *next)
{
+ unsigned long usage_mask = 0, forward_mask, backward_mask;
+ enum lock_usage_bit forward_bit = 0, backward_bit = 0;
+ struct lock_list *uninitialized_var(target_entry1);
+ struct lock_list *uninitialized_var(target_entry);
+ struct lock_list this, that;
+ int ret;
+
/*
- * 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>:
+ * Step 1: gather all hard/soft IRQs usages backward in an
+ * accumulated usage mask.
*/
- if (!check_usage(curr, prev, next, bit,
- exclusive_bit(bit), state_name(bit)))
- return 0;
+ this.parent = NULL;
+ this.class = hlock_class(prev);
+
+ ret = __bfs_backwards(&this, &usage_mask, usage_accumulate, NULL);
+ if (ret < 0)
+ return print_bfs_bug(ret);
- bit++; /* _READ */
+ usage_mask &= LOCKF_USED_IN_IRQ_ALL;
+ if (!usage_mask)
+ return 1;
/*
- * 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>:
+ * Step 2: find exclusive uses forward that match the previous
+ * backward accumulated mask.
*/
- if (!check_usage(curr, prev, next, bit,
- exclusive_bit(bit), state_name(bit)))
- return 0;
+ forward_mask = exclusive_mask(usage_mask);
- return 1;
-}
+ that.parent = NULL;
+ that.class = hlock_class(next);
-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
+ ret = find_usage_forwards(&that, forward_mask, &target_entry1);
+ if (ret < 0)
+ return print_bfs_bug(ret);
+ if (ret == 1)
+ return ret;
- return 1;
+ /*
+ * Step 3: we found a bad match! Now retrieve a lock from the backward
+ * list whose usage mask matches the exclusive usage mask from the
+ * lock found on the forward list.
+ */
+ backward_mask = original_mask(target_entry1->class->usage_mask);
+
+ ret = find_usage_backwards(&this, backward_mask, &target_entry);
+ if (ret < 0)
+ return print_bfs_bug(ret);
+ if (DEBUG_LOCKS_WARN_ON(ret == 1))
+ return 1;
+
+ /*
+ * Step 4: narrow down to a pair of incompatible usage bits
+ * and report it.
+ */
+ ret = find_exclusive_match(target_entry->class->usage_mask,
+ target_entry1->class->usage_mask,
+ &backward_bit, &forward_bit);
+ if (DEBUG_LOCKS_WARN_ON(ret == -1))
+ return 1;
+
+ return print_bad_irq_dependency(curr, &this, &that,
+ target_entry, target_entry1,
+ prev, next,
+ backward_bit, forward_bit,
+ state_name(backward_bit));
}
static void inc_chains(void)
@@ -2030,9 +2128,8 @@ static void inc_chains(void)
#else
-static inline int
-check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
- struct held_lock *next)
+static inline int check_irq_usage(struct task_struct *curr,
+ struct held_lock *prev, struct held_lock *next)
{
return 1;
}
@@ -2211,7 +2308,7 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev,
else if (unlikely(ret < 0))
return print_bfs_bug(ret);
- if (!check_prev_add_irq(curr, prev, next))
+ if (!check_irq_usage(curr, prev, next))
return 0;
/*
@@ -2773,6 +2870,12 @@ static void check_chain_key(struct task_struct *curr)
#endif
}
+static int mark_lock(struct task_struct *curr, struct held_lock *this,
+ enum lock_usage_bit new_bit);
+
+#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
+
+
static void
print_usage_bug_scenario(struct held_lock *lock)
{
@@ -2842,10 +2945,6 @@ valid_state(struct task_struct *curr, struct held_lock *this,
return 1;
}
-static int mark_lock(struct task_struct *curr, struct held_lock *this,
- enum lock_usage_bit new_bit);
-
-#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
/*
* print irq inversion bug:
@@ -2925,7 +3024,7 @@ check_usage_forwards(struct task_struct *curr, struct held_lock *this,
root.parent = NULL;
root.class = hlock_class(this);
- ret = find_usage_forwards(&root, bit, &target_entry);
+ ret = find_usage_forwards(&root, lock_flag(bit), &target_entry);
if (ret < 0)
return print_bfs_bug(ret);
if (ret == 1)
@@ -2949,7 +3048,7 @@ check_usage_backwards(struct task_struct *curr, struct held_lock *this,
root.parent = NULL;
root.class = hlock_class(this);
- ret = find_usage_backwards(&root, bit, &target_entry);
+ ret = find_usage_backwards(&root, lock_flag(bit), &target_entry);
if (ret < 0)
return print_bfs_bug(ret);
if (ret == 1)
@@ -3004,7 +3103,7 @@ static int (*state_verbose_f[])(struct lock_class *class) = {
static inline int state_verbose(enum lock_usage_bit bit,
struct lock_class *class)
{
- return state_verbose_f[bit >> 2](class);
+ return state_verbose_f[bit >> LOCK_USAGE_DIR_MASK](class);
}
typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
@@ -3146,7 +3245,7 @@ void lockdep_hardirqs_on(unsigned long ip)
/*
* See the fine text that goes along with this variable definition.
*/
- if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
+ if (DEBUG_LOCKS_WARN_ON(early_boot_irqs_disabled))
return;
/*