diff options
Diffstat (limited to 'kernel/locking/lockdep.c')
| -rw-r--r-- | kernel/locking/lockdep.c | 267 |
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; /* |