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| author | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-12-11 09:10:42 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-12-11 09:10:42 +0100 |
| commit | e045e18dbf3eaac32cdeb2799a5ec84fa694636c (patch) | |
| tree | d105f70b32d8d0af07e2c5688849c93d25832933 /lib/objpool.c | |
| parent | ae5af710f369a4d88792bf1d9da317884156cd87 (diff) | |
| parent | a39b6ac3781d46ba18193c9dbb2110f31e9bffe9 (diff) | |
| download | lwn-e045e18dbf3eaac32cdeb2799a5ec84fa694636c.tar.gz lwn-e045e18dbf3eaac32cdeb2799a5ec84fa694636c.zip | |
Merge 6.7-rc5 into tty-next
We need the serial fixes in here as well to build off of.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'lib/objpool.c')
| -rw-r--r-- | lib/objpool.c | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/lib/objpool.c b/lib/objpool.c index ce0087f64400..cfdc02420884 100644 --- a/lib/objpool.c +++ b/lib/objpool.c @@ -201,6 +201,23 @@ static inline void *objpool_try_get_slot(struct objpool_head *pool, int cpu) while (head != READ_ONCE(slot->last)) { void *obj; + /* + * data visibility of 'last' and 'head' could be out of + * order since memory updating of 'last' and 'head' are + * performed in push() and pop() independently + * + * before any retrieving attempts, pop() must guarantee + * 'last' is behind 'head', that is to say, there must + * be available objects in slot, which could be ensured + * by condition 'last != head && last - head <= nr_objs' + * that is equivalent to 'last - head - 1 < nr_objs' as + * 'last' and 'head' are both unsigned int32 + */ + if (READ_ONCE(slot->last) - head - 1 >= pool->nr_objs) { + head = READ_ONCE(slot->head); + continue; + } + /* obj must be retrieved before moving forward head */ obj = READ_ONCE(slot->entries[head & slot->mask]); |