Re: [PATCH v10 20/24] coresight: cti: increase reference count when enabling cti

[Mathieu Poirier]

On Fri, Aug 21, 2020 at 11:44:41AM +0800, Tingwei Zhang wrote:
> 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 
> Signed-off-by: Tingwei Zhang 
> ---

Reviewed-by: Mathieu Poirier 

>  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 d354fd57474e..6c9f6930b8b8 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;
>   }
>   }
> -- 
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
> 

[PATCH v10 20/24] coresight: cti: increase reference count when enabling cti

[Tingwei Zhang]

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 
Signed-off-by: Tingwei Zhang 
---
 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 d354fd57474e..6c9f6930b8b8 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;
}
}
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project