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coresight: Add try_get_module() in coresight_grab_device()

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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>
This commit is contained in:
Tingwei Zhang 2020-09-28 10:34:54 -06:00 committed by Greg Kroah-Hartman
parent d735d925f9
commit 32b0707a41
1 changed files with 53 additions and 7 deletions
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60
drivers/hwtracing/coresight/coresight.c
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@ -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;
}
pm_runtime_get_sync(csdev->dev.parent);
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);
}
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);