staging: zcache: fix serialization bug in zv stats
In a multithreaded workload, the zv_curr_dist_counts
and zv_cumul_dist_counts statistics are being corrupted
because the increments and decrements in zv_create
and zv_free are not atomic.
This patch converts these statistics and their corresponding
increments/decrements/reads to atomic operations.
Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Acked-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/staging/zcache/zcache-main.c b/drivers/staging/zcache/zcache-main.c
index ce070877..ef7c52b 100644
--- a/drivers/staging/zcache/zcache-main.c
+++ b/drivers/staging/zcache/zcache-main.c
@@ -654,8 +654,8 @@
*/
static unsigned int zv_max_mean_zsize = (PAGE_SIZE / 8) * 5;
-static unsigned long zv_curr_dist_counts[NCHUNKS];
-static unsigned long zv_cumul_dist_counts[NCHUNKS];
+static atomic_t zv_curr_dist_counts[NCHUNKS];
+static atomic_t zv_cumul_dist_counts[NCHUNKS];
static struct zv_hdr *zv_create(struct xv_pool *xvpool, uint32_t pool_id,
struct tmem_oid *oid, uint32_t index,
@@ -674,8 +674,8 @@
&page, &offset, ZCACHE_GFP_MASK);
if (unlikely(ret))
goto out;
- zv_curr_dist_counts[chunks]++;
- zv_cumul_dist_counts[chunks]++;
+ atomic_inc(&zv_curr_dist_counts[chunks]);
+ atomic_inc(&zv_cumul_dist_counts[chunks]);
zv = kmap_atomic(page, KM_USER0) + offset;
zv->index = index;
zv->oid = *oid;
@@ -697,7 +697,7 @@
ASSERT_SENTINEL(zv, ZVH);
BUG_ON(chunks >= NCHUNKS);
- zv_curr_dist_counts[chunks]--;
+ atomic_dec(&zv_curr_dist_counts[chunks]);
size -= sizeof(*zv);
BUG_ON(size == 0);
INVERT_SENTINEL(zv, ZVH);
@@ -737,7 +737,7 @@
char *p = buf;
for (i = 0; i < NCHUNKS; i++) {
- n = zv_curr_dist_counts[i];
+ n = atomic_read(&zv_curr_dist_counts[i]);
p += sprintf(p, "%lu ", n);
chunks += n;
sum_total_chunks += i * n;
@@ -753,7 +753,7 @@
char *p = buf;
for (i = 0; i < NCHUNKS; i++) {
- n = zv_cumul_dist_counts[i];
+ n = atomic_read(&zv_cumul_dist_counts[i]);
p += sprintf(p, "%lu ", n);
chunks += n;
sum_total_chunks += i * n;
