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@xxxxxxxxxxxxxxxxx>
---
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);
}
--
2.7.4
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