From 54561783ee99d73a086f3abbda3e44f87f6bf65b Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Wed, 5 Dec 2007 15:46:09 +0100 Subject: [PATCH] lockdep: in_range() fix Torsten Kaiser wrote: | static inline int in_range(const void *start, const void *addr, const void *end) | { | return addr >= start && addr <= end; | } | This will return true, if addr is in the range of start (including) | to end (including). | | But debug_check_no_locks_freed() seems does: | const void *mem_to = mem_from + mem_len | -> mem_to is the last byte of the freed range, that fits in_range | lock_from = (void *)hlock->instance; | -> first byte of the lock | lock_to = (void *)(hlock->instance + 1); | -> first byte of the next lock, not last byte of the lock that is being checked! | | The test is: | if (!in_range(mem_from, lock_from, mem_to) && | !in_range(mem_from, lock_to, mem_to)) | continue; | So it tests, if the first byte of the lock is in the range that is freed ->OK | And if the first byte of the *next* lock is in the range that is freed | -> Not OK. We can also simplify in_range checks, we need only 2 comparisons, not 4. If the lock is not in memory range, it should be either at the left of range or at the right. Signed-off-by: Oleg Nesterov Signed-off-by: Ingo Molnar Signed-off-by: Peter Zijlstra --- kernel/lockdep.c | 22 ++++++++++------------ 1 file changed, 10 insertions(+), 12 deletions(-) diff --git a/kernel/lockdep.c b/kernel/lockdep.c index 7e2ca7c9d99..0f389621bb6 100644 --- a/kernel/lockdep.c +++ b/kernel/lockdep.c @@ -3054,11 +3054,6 @@ void __init lockdep_info(void) #endif } -static inline int in_range(const void *start, const void *addr, const void *end) -{ - return addr >= start && addr <= end; -} - static void print_freed_lock_bug(struct task_struct *curr, const void *mem_from, const void *mem_to, struct held_lock *hlock) @@ -3080,6 +3075,13 @@ print_freed_lock_bug(struct task_struct *curr, const void *mem_from, dump_stack(); } +static inline int not_in_range(const void* mem_from, unsigned long mem_len, + const void* lock_from, unsigned long lock_len) +{ + return lock_from + lock_len <= mem_from || + mem_from + mem_len <= lock_from; +} + /* * Called when kernel memory is freed (or unmapped), or if a lock * is destroyed or reinitialized - this code checks whether there is @@ -3087,7 +3089,6 @@ print_freed_lock_bug(struct task_struct *curr, const void *mem_from, */ void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len) { - const void *mem_to = mem_from + mem_len, *lock_from, *lock_to; struct task_struct *curr = current; struct held_lock *hlock; unsigned long flags; @@ -3100,14 +3101,11 @@ void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len) for (i = 0; i < curr->lockdep_depth; i++) { hlock = curr->held_locks + i; - lock_from = (void *)hlock->instance; - lock_to = (void *)(hlock->instance + 1); - - if (!in_range(mem_from, lock_from, mem_to) && - !in_range(mem_from, lock_to, mem_to)) + if (not_in_range(mem_from, mem_len, hlock->instance, + sizeof(*hlock->instance))) continue; - print_freed_lock_bug(curr, mem_from, mem_to, hlock); + print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock); break; } local_irq_restore(flags);