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eina_threadqueue: add locking for variable used between threads 

Summary:
the 'first' member of this struct is used simultaneously across
threads and can have conflicting read/write operations occurring at this
time

as int operations are not guaranteed to be atomic, ensure that we are
using atomic operations or locking as necessary

@fix

Depends on D6299

Reviewers: ManMower, devilhorns

Reviewed By: ManMower

Subscribers: cedric, #committers

Tags: #efl

Differential Revision: https://phab.enlightenment.org/D6300
This commit is contained in:
Mike Blumenkrantz 2018-06-19 13:30:44 -04:00
parent a446fb86fc
commit 6353a699e3
1 changed files with 22 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
src/lib/eina/eina_thread_queue.c
View File

@ -57,6 +57,7 @@ struct _Eina_Thread_Queue_Msg_Block
Eina_Lock lock_non_0_ref; // block non-0 ref state
#ifndef ATOMIC
Eina_Spinlock lock_ref; // lock for ref field
Eina_Spinlock lock_first; // lock for first field
#endif
int ref; // the number of open reads/writes
int size; // the total allocated bytes of data[]
@ -124,6 +125,7 @@ _eina_thread_queue_msg_block_new(int size)
blk->next = NULL;
#ifndef ATOMIC
eina_spinlock_new(&(blk->lock_ref));
eina_spinlock_new(&(blk->lock_first));
#endif
eina_lock_new(&(blk->lock_non_0_ref));
blk->size = size;
@ -144,6 +146,9 @@ _eina_thread_queue_msg_block_real_free(Eina_Thread_Queue_Msg_Block *blk)
eina_spinlock_take(&(blk->lock_ref));
eina_spinlock_release(&(blk->lock_ref));
eina_spinlock_free(&(blk->lock_ref));
eina_spinlock_take(&(blk->lock_first));
eina_spinlock_release(&(blk->lock_first));
eina_spinlock_free(&(blk->lock_first));
#endif
free(blk);
}
@ -294,7 +299,7 @@ _eina_thread_queue_msg_fetch(Eina_Thread_Queue *thq, Eina_Thread_Queue_Msg_Block
{
Eina_Thread_Queue_Msg_Block *blk;
Eina_Thread_Queue_Msg *msg;
int ref;
int ref, first;
if (!thq->read)
{
@ -321,9 +326,17 @@ _eina_thread_queue_msg_fetch(Eina_Thread_Queue *thq, Eina_Thread_Queue_Msg_Block
RWLOCK_UNLOCK(&(thq->lock_write));
}
blk = thq->read;
#ifdef ATOMIC
__atomic_load(&blk->first, &first, __ATOMIC_RELAXED);
msg = (Eina_Thread_Queue_Msg *)((char *)(&(blk->data[0])) + first);
first = __atomic_add_fetch(&(blk->first), msg->size, __ATOMIC_RELAXED);
#else
eina_spinlock_take(&blk->lock_first);
msg = (Eina_Thread_Queue_Msg *)((char *)(&(blk->data[0])) + blk->first);
blk->first += msg->size;
if (blk->first >= blk->last) thq->read = NULL;
first = blk->first += msg->size;
eina_spinlock_release(&blk->lock_first);
#endif
if (first >= blk->last) thq->read = NULL;
*blkret = blk;
#ifdef ATOMIC
__atomic_add_fetch(&(blk->ref), 1, __ATOMIC_RELAXED);
@ -338,17 +351,21 @@ _eina_thread_queue_msg_fetch(Eina_Thread_Queue *thq, Eina_Thread_Queue_Msg_Block
static void
_eina_thread_queue_msg_fetch_done(Eina_Thread_Queue_Msg_Block *blk)
{
int ref;
int ref, first;
#ifdef ATOMIC
ref = __atomic_sub_fetch(&(blk->ref), 1, __ATOMIC_RELAXED);
__atomic_load(&blk->first, &first, __ATOMIC_RELAXED);
#else
eina_spinlock_take(&(blk->lock_ref));
blk->ref--;
ref = blk->ref;
eina_spinlock_release(&(blk->lock_ref));
eina_spinlock_take(&blk->lock_first);
first = blk->first;
eina_spinlock_release(&blk->lock_first);
#endif
if ((blk->first >= blk->last) && (ref == 0))
if ((first >= blk->last) && (ref == 0))
_eina_thread_queue_msg_block_free(blk);
}