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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 <oleg@tv-sign.ru>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
This commit is contained in:
Oleg Nesterov 2007-12-05 15:46:09 +01:00 committed by Ingo Molnar
parent 856848737b
commit 54561783ee
1 changed files with 10 additions and 12 deletions
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22
kernel/lockdep.c
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@ -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);