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Commit 2a483011 authored by Seth Jennings's avatar Seth Jennings Committed by Greg Kroah-Hartman
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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: default avatarSeth Jennings <sjenning@linux.vnet.ibm.com>
Acked-by: default avatarDan Magenheimer <dan.magenheimer@oracle.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent a9d3c9e3

drivers/staging/zcache/zcache-main.c

+7 −7
Original line number Diff line number Diff line
@@ -654,8 +654,8 @@ static unsigned int zv_max_zsize = (PAGE_SIZE / 8) * 7; 
 */

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 @@ static struct zv_hdr *zv_create(struct xv_pool *xvpool, uint32_t pool_id, 
			&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 @@ static void zv_free(struct xv_pool *xvpool, struct zv_hdr *zv) 


	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 @@ static int zv_curr_dist_counts_show(char *buf) 
	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 @@ static int zv_cumul_dist_counts_show(char *buf) 
	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;