2005-01-09 08:53:56

by Alexey Dobriyan

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Subject: [PATCH] futex: s/0/NULL/ in pointer context

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Signed-off-by: Alexey Dobriyan <[email protected]>

Index: linux-2.6.10-bk11-warnings/kernel/futex.c
===================================================================
--- linux-2.6.10-bk11-warnings/kernel/futex.c (revision 4)
+++ linux-2.6.10-bk11-warnings/kernel/futex.c (revision 5)
@@ -236,7 +236,7 @@
*/
static inline void get_key_refs(union futex_key *key)
{
- if (key->both.ptr != 0) {
+ if (key->both.ptr != NULL) {
if (key->both.offset & 1)
atomic_inc(&key->shared.inode->i_count);
else
@@ -250,7 +250,7 @@
*/
static void drop_key_refs(union futex_key *key)
{
- if (key->both.ptr != 0) {
+ if (key->both.ptr != NULL) {
if (key->both.offset & 1)
iput(key->shared.inode);
else
@@ -445,7 +445,7 @@
/* In the common case we don't take the spinlock, which is nice. */
retry:
lock_ptr = q->lock_ptr;
- if (lock_ptr != 0) {
+ if (lock_ptr != NULL) {
spin_lock(lock_ptr);
/*
* q->lock_ptr can change between reading it and

2005-01-09 14:27:14

by Arnd Bergmann

[permalink] [raw]

Subject: Re: [PATCH] futex: s/0/NULL/ in pointer context

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On S?nndag 09 Januar 2005 10:23, Alexey Dobriyan wrote:
> @@ -236,7 +236,7 @@
> */
> static inline void get_key_refs(union futex_key *key)
> {
> - if (key->both.ptr != 0) {
> + if (key->both.ptr != NULL) {
> if (key->both.offset & 1)
> atomic_inc(&key->shared.inode->i_count);
> else

Actually, many consider the preferred way to write this

if (key->both.ptr) {

instead, since the condition you want to check is 'is key->both.ptr
a valid pointer', not 'is key->both.ptr inequal to the invalid
pointer'. The normal use for NULL is only in assignments and
initializations, not in comparisons.

Arnd <><

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