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authorMohit Agrawal <moagrawal@redhat.com>2019-10-03 14:06:52 +0530
committerhari gowtham <hari.gowtham005@gmail.com>2019-12-26 06:04:33 +0000
commit3d3f74fdf195f9cec3c9c79ae8f2fa50720fd09f (patch)
tree31b13db0cd0b67f1236be2a51358137e5820c373
parent308991a977a6e3d5725de5321710d6dcf4983bb3 (diff)
rpc: Synchronize slot allocation code
Problem: Current slot allocation/deallocation code path is not synchronized.There are scenario when due to race condition in slot allocation/deallocation code path brick is crashed. Solution: Synchronize slot allocation/deallocation code path to avoid the issue > Change-Id: I4fb659a75234218ffa0e5e0bf9308f669f75fc25 > Fixes: bz#1763036 > Signed-off-by: Mohit Agrawal <moagrawal@redhat.com> > (cherry picked from commit faf5ac13c4ee00a05e9451bf8da3be2a9043bbf2) Change-Id: I4fb659a75234218ffa0e5e0bf9308f669f75fc25 Fixes: bz#1778182 Signed-off-by: Mohit Agrawal <moagrawal@redhat.com>
-rw-r--r--libglusterfs/src/event-epoll.c76
1 files changed, 42 insertions, 34 deletions
diff --git a/libglusterfs/src/event-epoll.c b/libglusterfs/src/event-epoll.c
index 0cec47e..5afb2f2 100644
--- a/libglusterfs/src/event-epoll.c
+++ b/libglusterfs/src/event-epoll.c
@@ -69,18 +69,30 @@ __event_newtable(struct event_pool *event_pool, int table_idx)
}
static int
+event_slot_ref(struct event_slot_epoll *slot)
+{
+ if (!slot)
+ return -1;
+
+ return GF_ATOMIC_INC(slot->ref);
+}
+
+static int
__event_slot_alloc(struct event_pool *event_pool, int fd,
- char notify_poller_death)
+ char notify_poller_death, struct event_slot_epoll **slot)
{
int i = 0;
+ int j = 0;
int table_idx = -1;
int gen = -1;
struct event_slot_epoll *table = NULL;
- for (i = 0; i < EVENT_EPOLL_TABLES; i++) {
+retry:
+
+ while (i < EVENT_EPOLL_TABLES) {
switch (event_pool->slots_used[i]) {
case EVENT_EPOLL_SLOTS:
- continue;
+ break;
case 0:
if (!event_pool->ereg[i]) {
table = __event_newtable(event_pool, i);
@@ -98,6 +110,7 @@ __event_slot_alloc(struct event_pool *event_pool, int fd,
if (table)
/* break out of the loop */
break;
+ i++;
}
if (!table)
@@ -105,20 +118,20 @@ __event_slot_alloc(struct event_pool *event_pool, int fd,
table_idx = i;
- for (i = 0; i < EVENT_EPOLL_SLOTS; i++) {
- if (table[i].fd == -1) {
+ for (j = 0; j < EVENT_EPOLL_SLOTS; j++) {
+ if (table[j].fd == -1) {
/* wipe everything except bump the generation */
- gen = table[i].gen;
- memset(&table[i], 0, sizeof(table[i]));
- table[i].gen = gen + 1;
+ gen = table[j].gen;
+ memset(&table[j], 0, sizeof(table[j]));
+ table[j].gen = gen + 1;
- LOCK_INIT(&table[i].lock);
- INIT_LIST_HEAD(&table[i].poller_death);
+ LOCK_INIT(&table[j].lock);
+ INIT_LIST_HEAD(&table[j].poller_death);
- table[i].fd = fd;
+ table[j].fd = fd;
if (notify_poller_death) {
- table[i].idx = table_idx * EVENT_EPOLL_SLOTS + i;
- list_add_tail(&table[i].poller_death,
+ table[j].idx = table_idx * EVENT_EPOLL_SLOTS + j;
+ list_add_tail(&table[j].poller_death,
&event_pool->poller_death);
}
@@ -128,18 +141,26 @@ __event_slot_alloc(struct event_pool *event_pool, int fd,
}
}
- return table_idx * EVENT_EPOLL_SLOTS + i;
+ if (j == EVENT_EPOLL_SLOTS) {
+ table = NULL;
+ i++;
+ goto retry;
+ } else {
+ (*slot) = &table[j];
+ event_slot_ref(*slot);
+ return table_idx * EVENT_EPOLL_SLOTS + j;
+ }
}
static int
event_slot_alloc(struct event_pool *event_pool, int fd,
- char notify_poller_death)
+ char notify_poller_death, struct event_slot_epoll **slot)
{
int idx = -1;
pthread_mutex_lock(&event_pool->mutex);
{
- idx = __event_slot_alloc(event_pool, fd, notify_poller_death);
+ idx = __event_slot_alloc(event_pool, fd, notify_poller_death, slot);
}
pthread_mutex_unlock(&event_pool->mutex);
@@ -153,6 +174,7 @@ __event_slot_dealloc(struct event_pool *event_pool, int idx)
int offset = 0;
struct event_slot_epoll *table = NULL;
struct event_slot_epoll *slot = NULL;
+ int fd = -1;
table_idx = idx / EVENT_EPOLL_SLOTS;
offset = idx % EVENT_EPOLL_SLOTS;
@@ -164,11 +186,13 @@ __event_slot_dealloc(struct event_pool *event_pool, int idx)
slot = &table[offset];
slot->gen++;
+ fd = slot->fd;
slot->fd = -1;
slot->handled_error = 0;
slot->in_handler = 0;
list_del_init(&slot->poller_death);
- event_pool->slots_used[table_idx]--;
+ if (fd != -1)
+ event_pool->slots_used[table_idx]--;
return;
}
@@ -185,15 +209,6 @@ event_slot_dealloc(struct event_pool *event_pool, int idx)
return;
}
-static int
-event_slot_ref(struct event_slot_epoll *slot)
-{
- if (!slot)
- return -1;
-
- return GF_ATOMIC_INC(slot->ref);
-}
-
static struct event_slot_epoll *
event_slot_get(struct event_pool *event_pool, int idx)
{
@@ -379,20 +394,13 @@ event_register_epoll(struct event_pool *event_pool, int fd,
if (destroy == 1)
goto out;
- idx = event_slot_alloc(event_pool, fd, notify_poller_death);
+ idx = event_slot_alloc(event_pool, fd, notify_poller_death, &slot);
if (idx == -1) {
gf_msg("epoll", GF_LOG_ERROR, 0, LG_MSG_SLOT_NOT_FOUND,
"could not find slot for fd=%d", fd);
return -1;
}
- slot = event_slot_get(event_pool, idx);
- if (!slot) {
- gf_msg("epoll", GF_LOG_ERROR, 0, LG_MSG_SLOT_NOT_FOUND,
- "could not find slot for fd=%d idx=%d", fd, idx);
- return -1;
- }
-
assert(slot->fd == fd);
LOCK(&slot->lock);