Earlier versions of the loopback code released the per-device mutex in-order to allow for more parallel asynchronous send/receive paths to execute. In the interim though new variables have been added to the struct gb_loopback{}; structure and as a result gb->send_count is now racy w/r to the controlling sysfs interface.
This patch fixes by holding gb->mutex between gb->send_count == gb->iteration_max and udelay() divide - in the sending kthread. Testing on DVT shows there's no adverse performance impact.
Signed-off-by: Bryan O'Donoghue pure.logic@nexus-software.ie --- drivers/staging/greybus/loopback.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/drivers/staging/greybus/loopback.c b/drivers/staging/greybus/loopback.c index de17901..66f54f9 100644 --- a/drivers/staging/greybus/loopback.c +++ b/drivers/staging/greybus/loopback.c @@ -524,7 +524,6 @@ static int gb_loopback_async_operation(struct gb_loopback *gb, int type,
atomic_inc(&gb->outstanding_operations);
- mutex_lock(&gb->mutex); timeout = gb->msec_timeout; ret = gb_operation_request_send_async_timeout(operation, timeout, gb_loopback_async_operation_callback, @@ -538,7 +537,6 @@ static int gb_loopback_async_operation(struct gb_loopback *gb, int type, gb_operation_put(operation); kfree(op_async); done: - mutex_unlock(&gb->mutex); return ret; }
@@ -918,7 +916,6 @@ static int gb_loopback_fn(void *data) type = gb->type; if (gb->ts.tv_usec == 0 && gb->ts.tv_sec == 0) do_gettimeofday(&gb->ts); - mutex_unlock(&gb->mutex);
/* Else operations to perform */ if (gb->async) { @@ -949,6 +946,7 @@ static int gb_loopback_fn(void *data) gb_loopback_calculate_stats(gb, !!error); } gb->send_count++; + mutex_unlock(&gb->mutex); if (us_wait) udelay(us_wait); }