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authorTingwei Zhang <tingwei@codeaurora.org>2020-09-28 10:34:54 -0600
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-09-28 19:47:40 +0200
commit32b0707a418219b38e17276075962e25e912d4b2 (patch)
treedf2c1adeb20cc12f5d0a793a7c640343e7d155a2 /drivers/hwtracing
parentd735d925f9a5029b8aaa5983d63c74f5cb4bfec0 (diff)
downloadlinux-32b0707a418219b38e17276075962e25e912d4b2.tar.bz2
coresight: Add try_get_module() in coresight_grab_device()
When coresight device is in an active session, driver module of that device should not be removed. Use try_get_module() in coresight_grab_device() to prevent module to be unloaded. Use get_device()/put_device() to protect device data in the middle of active session. Suggested-by: Suzuki K Poulose <suzuki.poulose@arm.com> Tested-by: Mike Leach <mike.leach@linaro.org> Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Tingwei Zhang <tingwei@codeaurora.org> Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org> Link: https://lore.kernel.org/r/20200928163513.70169-7-mathieu.poirier@linaro.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/hwtracing')
-rw-r--r--drivers/hwtracing/coresight/coresight.c60
1 files changed, 53 insertions, 7 deletions
diff --git a/drivers/hwtracing/coresight/coresight.c b/drivers/hwtracing/coresight/coresight.c
index d1aea3a1e7b6..4faa4aa3964d 100644
--- a/drivers/hwtracing/coresight/coresight.c
+++ b/drivers/hwtracing/coresight/coresight.c
@@ -629,13 +629,45 @@ struct coresight_device *coresight_get_sink_by_id(u32 id)
return dev ? to_coresight_device(dev) : NULL;
}
+/**
+ * coresight_get_ref- Helper function to increase reference count to module
+ * and device.
+ * Return true in successful case and power up the device.
+ * Return false when failed to get reference of module.
+ */
+static inline bool coresight_get_ref(struct coresight_device *csdev)
+{
+ struct device *dev = csdev->dev.parent;
+
+ /* Make sure the driver can't be removed */
+ if (!try_module_get(dev->driver->owner))
+ return false;
+ /* Make sure the device can't go away */
+ get_device(dev);
+ pm_runtime_get_sync(dev);
+ return true;
+}
+
+/**
+ * coresight_put_ref- Helper function to decrease reference count to module
+ * and device. Power off the device.
+ */
+static inline void coresight_put_ref(struct coresight_device *csdev)
+{
+ struct device *dev = csdev->dev.parent;
+
+ pm_runtime_put(dev);
+ put_device(dev);
+ module_put(dev->driver->owner);
+}
+
/*
* coresight_grab_device - Power up this device and any of the helper
* devices connected to it for trace operation. Since the helper devices
* don't appear on the trace path, they should be handled along with the
* the master device.
*/
-static void coresight_grab_device(struct coresight_device *csdev)
+static int coresight_grab_device(struct coresight_device *csdev)
{
int i;
@@ -644,9 +676,20 @@ static void coresight_grab_device(struct coresight_device *csdev)
child = csdev->pdata->conns[i].child_dev;
if (child && child->type == CORESIGHT_DEV_TYPE_HELPER)
- pm_runtime_get_sync(child->dev.parent);
+ if (!coresight_get_ref(child))
+ goto err;
+ }
+ if (coresight_get_ref(csdev))
+ return 0;
+err:
+ for (i--; i >= 0; i--) {
+ struct coresight_device *child;
+
+ child = csdev->pdata->conns[i].child_dev;
+ if (child && child->type == CORESIGHT_DEV_TYPE_HELPER)
+ coresight_put_ref(child);
}
- pm_runtime_get_sync(csdev->dev.parent);
+ return -ENODEV;
}
/*
@@ -657,13 +700,13 @@ static void coresight_drop_device(struct coresight_device *csdev)
{
int i;
- pm_runtime_put(csdev->dev.parent);
+ coresight_put_ref(csdev);
for (i = 0; i < csdev->pdata->nr_outport; i++) {
struct coresight_device *child;
child = csdev->pdata->conns[i].child_dev;
if (child && child->type == CORESIGHT_DEV_TYPE_HELPER)
- pm_runtime_put(child->dev.parent);
+ coresight_put_ref(child);
}
}
@@ -682,7 +725,7 @@ static int _coresight_build_path(struct coresight_device *csdev,
struct coresight_device *sink,
struct list_head *path)
{
- int i;
+ int i, ret;
bool found = false;
struct coresight_node *node;
@@ -712,11 +755,14 @@ out:
* is tell the PM runtime core we need this element and add a node
* for it.
*/
+ ret = coresight_grab_device(csdev);
+ if (ret)
+ return ret;
+
node = kzalloc(sizeof(struct coresight_node), GFP_KERNEL);
if (!node)
return -ENOMEM;
- coresight_grab_device(csdev);
node->csdev = csdev;
list_add(&node->link, path);