Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=54561783ee99d73a086f3abbda3e44f87f6bf65b
Commit:     54561783ee99d73a086f3abbda3e44f87f6bf65b
Parent:     856848737bd944c1db3ce0a66bbf67e56bd6f77d
Author:     Oleg Nesterov <[EMAIL PROTECTED]>
AuthorDate: Wed Dec 5 15:46:09 2007 +0100
Committer:  Ingo Molnar <[EMAIL PROTECTED]>
CommitDate: Wed Dec 5 15:46:09 2007 +0100

    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 <[EMAIL PROTECTED]>
    Signed-off-by: Ingo Molnar <[EMAIL PROTECTED]>
    Signed-off-by: Peter Zijlstra <[EMAIL PROTECTED]>
---
 kernel/lockdep.c |   22 ++++++++++------------
 1 files changed, 10 insertions(+), 12 deletions(-)

diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 7e2ca7c..0f38962 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);
-
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