[PATCH v8 20/24] coresight: cti: increase reference count when enabling cti

Tingwei Zhang
2020-08-07T11:17:38Z

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>
---
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 27ad8317e3cf..8dcd73ea33b4 100644
--- a/drivers/hwtracing/coresight/coresight.c
+++ b/drivers/hwtracing/coresight/coresight.c
@@ -242,19 +242,30 @@ 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;
}
}
--
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