[PATCH v11 20/24] coresight: cti: increase reference count when enabling cti

Tingwei Zhang
2020-09-15T10:49:01Z

CTI device is enabled when associated coresight device is enabled.
Increase the module and device reference count for CTI device
when it's enabled. This can prevent CTI device be removed or
module be unloaded when CTI device is enabled by an active trace
session.

Signed-off-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: Tingwei Zhang <tingwei@codeaurora.org>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
---
drivers/hwtracing/coresight/coresight.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight.c b/drivers/hwtracing/coresight/coresight.c
index 711beb92166a..546c97045afe 100644
--- a/drivers/hwtracing/coresight/coresight.c
+++ b/drivers/hwtracing/coresight/coresight.c
@@ -241,19 +241,30 @@ coresight_control_assoc_ectdev(struct coresight_device *csdev, bool enable)
{
int ect_ret = 0;
struct coresight_device *ect_csdev = csdev->ect_dev;
+ struct module *mod;

if (!ect_csdev)
return 0;
if ((!ect_ops(ect_csdev)->enable) || (!ect_ops(ect_csdev)->disable))
return 0;

+ mod = ect_csdev->dev.parent->driver->owner;
if (enable) {
- ect_ret = ect_ops(ect_csdev)->enable(ect_csdev);
- if (!ect_ret)
- csdev->ect_enabled = true;
+ if (try_module_get(mod)) {
+ ect_ret = ect_ops(ect_csdev)->enable(ect_csdev);
+ if (ect_ret) {
+ module_put(mod);
+ } else {
+ get_device(ect_csdev->dev.parent);
+ csdev->ect_enabled = true;
+ }
+ } else
+ ect_ret = -ENODEV;
} else {
if (csdev->ect_enabled) {
ect_ret = ect_ops(ect_csdev)->disable(ect_csdev);
+ put_device(ect_csdev->dev.parent);
+ module_put(mod);
csdev->ect_enabled = false;