diff options
| author | Alexander Motin <[email protected]> | 2021-08-17 11:44:34 -0400 |
|---|---|---|
| committer | Tony Hutter <[email protected]> | 2021-09-14 14:31:01 -0700 |
| commit | 5afc35b69824db01b36418e8f091ffeaeaeb98c9 (patch) | |
| tree | 87550992a8d5f8d743a25ac3c8c754ce6490d0fb /include | |
| parent | c6c0d30016ff344a91aacc8057d5fb392c5ea9c7 (diff) | |
Use more atomics in refcounts
Use atomic_load_64() for zfs_refcount_count() to prevent torn reads
on 32-bit platforms. On 64-bit ones it should not change anything.
When built with ZFS_DEBUG but running without tracking enabled use
atomics instead of mutexes same as for builds without ZFS_DEBUG.
Since rc_tracked can't change live we can check it without lock.
Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed-by: Matthew Ahrens <[email protected]>
Signed-off-by: Alexander Motin <[email protected]>
Closes #12420
Diffstat (limited to 'include')
| -rw-r--r-- | include/sys/zfs_refcount.h | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/include/sys/zfs_refcount.h b/include/sys/zfs_refcount.h index fc0cbea1c..1e6449472 100644 --- a/include/sys/zfs_refcount.h +++ b/include/sys/zfs_refcount.h @@ -96,8 +96,8 @@ typedef struct refcount { #define zfs_refcount_create_tracked(rc) ((rc)->rc_count = 0) #define zfs_refcount_destroy(rc) ((rc)->rc_count = 0) #define zfs_refcount_destroy_many(rc, number) ((rc)->rc_count = 0) -#define zfs_refcount_is_zero(rc) ((rc)->rc_count == 0) -#define zfs_refcount_count(rc) ((rc)->rc_count) +#define zfs_refcount_is_zero(rc) (zfs_refcount_count(rc) == 0) +#define zfs_refcount_count(rc) atomic_load_64(&(rc)->rc_count) #define zfs_refcount_add(rc, holder) atomic_inc_64_nv(&(rc)->rc_count) #define zfs_refcount_remove(rc, holder) atomic_dec_64_nv(&(rc)->rc_count) #define zfs_refcount_add_many(rc, number, holder) \ @@ -105,13 +105,13 @@ typedef struct refcount { #define zfs_refcount_remove_many(rc, number, holder) \ atomic_add_64_nv(&(rc)->rc_count, -number) #define zfs_refcount_transfer(dst, src) { \ - uint64_t __tmp = (src)->rc_count; \ + uint64_t __tmp = zfs_refcount_count(src); \ atomic_add_64(&(src)->rc_count, -__tmp); \ atomic_add_64(&(dst)->rc_count, __tmp); \ } #define zfs_refcount_transfer_ownership(rc, ch, nh) ((void)0) #define zfs_refcount_transfer_ownership_many(rc, nr, ch, nh) ((void)0) -#define zfs_refcount_held(rc, holder) ((rc)->rc_count > 0) +#define zfs_refcount_held(rc, holder) (zfs_refcount_count(rc) > 0) #define zfs_refcount_not_held(rc, holder) (B_TRUE) #define zfs_refcount_init() |