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authorJeff Darcy <jdarcy@redhat.com>2015-04-28 04:40:00 -0400
committerVijay Bellur <vbellur@redhat.com>2015-05-09 06:28:13 -0700
commitc085871e3919df2b309b76633e75d5449899437a (patch)
tree798d6c1438e4a4fd17187d188bf4cf4bf0ac6a54 /libglusterfs/src/xlator.c
parent4a15d32643fe149764239eabcf6ba53eb32faf63 (diff)
core: use reference counting for mem_acct structures
When freeing memory, our memory-accounting code expects to be able to dereference from the (previously) allocated block to its owning translator. However, as we have already found once in option validation and twice in logging, that translator might itself have been freed and the dereference attempt causes on of our daemons to crash with SIGSEGV. This patch attempts to fix that as follows: * We no longer embed a struct mem_acct directly in a struct xlator, but instead allocate it separately. * Allocated memory blocks now contain a pointer to the mem_acct instead of the xlator. * The mem_acct structure contains a reference count, manipulated in both the normal and translator allocate/free code using atomic increments and decrements. * Because it's now a separate structure, we can defer freeing the mem_acct until its reference count reaches zero (either way). * Some unit tests were disabled, because they embedded their own copies of the implementation for what they were supposedly testing. Life's too short to spend time fixing tests that seem designed to impede progress by requiring a certain implementation as well as behavior. Change-Id: Id929b11387927136f78626901729296b6c0d0fd7 BUG: 1211749 Signed-off-by: Jeff Darcy <jdarcy@redhat.com> Reviewed-on: http://review.gluster.org/10417 Tested-by: Gluster Build System <jenkins@build.gluster.com> Reviewed-by: Krishnan Parthasarathi <kparthas@redhat.com> Reviewed-by: Niels de Vos <ndevos@redhat.com> Reviewed-by: Pranith Kumar Karampuri <pkarampu@redhat.com>
Diffstat (limited to 'libglusterfs/src/xlator.c')
-rw-r--r--libglusterfs/src/xlator.c42
1 files changed, 23 insertions, 19 deletions
diff --git a/libglusterfs/src/xlator.c b/libglusterfs/src/xlator.c
index c670ee97aee..628f3499956 100644
--- a/libglusterfs/src/xlator.c
+++ b/libglusterfs/src/xlator.c
@@ -509,16 +509,22 @@ xlator_mem_acct_init (xlator_t *xl, int num_types)
if (!xl->ctx->mem_acct_enable)
return 0;
- xl->mem_acct.num_types = num_types;
- xl->mem_acct.rec = CALLOC(num_types, sizeof(struct mem_acct_rec));
+ xl->mem_acct = MALLOC (sizeof(struct mem_acct)
+ + sizeof(struct mem_acct_rec) * num_types);
- if (!xl->mem_acct.rec) {
+ if (!xl->mem_acct) {
return -1;
}
+ memset (xl->mem_acct, 0, sizeof(struct mem_acct));
+
+ xl->mem_acct->num_types = num_types;
+ LOCK_INIT (&xl->mem_acct->lock);
+ xl->mem_acct->refcnt = 1;
for (i = 0; i < num_types; i++) {
- ret = LOCK_INIT(&(xl->mem_acct.rec[i].lock));
+ memset (&xl->mem_acct->rec[i], 0, sizeof(struct mem_acct_rec));
+ ret = LOCK_INIT(&(xl->mem_acct->rec[i].lock));
if (ret) {
fprintf(stderr, "Unable to lock..errno : %d",errno);
}
@@ -559,17 +565,22 @@ xlator_list_destroy (xlator_list_t *list)
static int
xlator_memrec_free (xlator_t *xl)
{
- uint32_t i = 0;
+ uint32_t i = 0;
+ struct mem_acct *mem_acct = NULL;
- if (!xl)
+ if (!xl) {
return 0;
+ }
+ mem_acct = xl->mem_acct;
- if (xl->mem_acct.rec) {
- for (i = 0; i < xl->mem_acct.num_types; i++) {
- LOCK_DESTROY (&(xl->mem_acct.rec[i].lock));
+ if (mem_acct) {
+ for (i = 0; i < mem_acct->num_types; i++) {
+ LOCK_DESTROY (&(mem_acct->rec[i].lock));
+ }
+ if (DECREMENT_ATOMIC (mem_acct->lock, mem_acct->refcnt) == 0) {
+ FREE (mem_acct);
+ xl->mem_acct = NULL;
}
- FREE (xl->mem_acct.rec);
- xl->mem_acct.rec = NULL;
}
return 0;
@@ -653,7 +664,6 @@ xlator_tree_free_memacct (xlator_t *tree)
{
xlator_t *trav = tree;
xlator_t *prev = tree;
- int i = 0;
if (!tree) {
gf_log ("parser", GF_LOG_ERROR, "Translator tree not found");
@@ -662,13 +672,7 @@ xlator_tree_free_memacct (xlator_t *tree)
while (prev) {
trav = prev->next;
- if (prev->mem_acct.rec) {
- for (i = 0; i < prev->mem_acct.num_types; i++) {
- LOCK_DESTROY (&(prev->mem_acct.rec[i].lock));
- }
- FREE (prev->mem_acct.rec);
- }
- GF_FREE (prev);
+ xlator_memrec_free (prev);
prev = trav;
}