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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: Seth Jennings <sjenning@linux.vnet.ibm.com>
Acked-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Seth Jennings 2011-12-30 10:42:15 -06:00 committed by Greg Kroah-Hartman
parent a9d3c9e3c5
commit 2a4830110b
1 changed files with 7 additions and 7 deletions
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14
drivers/staging/zcache/zcache-main.c
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@ -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;