When cdev_add is called after device_add has been called there is no
way for the userspace to know about the addition of a cdev as cdev_add
itself doesn't trigger a uevent notification, or for the kernel to
know about the change to devt. This results in two problems:
- mknod is never called for the cdev and hence no cdev appears on
devtmpfs.
- sysfs links to the new cdev are not established.
The cdev needs to be added and devt assigned before device_add() is
called in order for the relevant sysfs and devtmpfs entries to be
created and the uevent to be properly populated.
Signed-off-by: Siddharth Gupta <[email protected]>
---
drivers/remoteproc/remoteproc_core.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
index 626a6b90f..562355a 100644
--- a/drivers/remoteproc/remoteproc_core.c
+++ b/drivers/remoteproc/remoteproc_core.c
@@ -2316,6 +2316,11 @@ int rproc_add(struct rproc *rproc)
struct device *dev = &rproc->dev;
int ret;
+ /* add char device for this remoteproc */
+ ret = rproc_char_device_add(rproc);
+ if (ret < 0)
+ return ret;
+
ret = device_add(dev);
if (ret < 0)
return ret;
@@ -2329,11 +2334,6 @@ int rproc_add(struct rproc *rproc)
/* create debugfs entries */
rproc_create_debug_dir(rproc);
- /* add char device for this remoteproc */
- ret = rproc_char_device_add(rproc);
- if (ret < 0)
- return ret;
-
/* if rproc is marked always-on, request it to boot */
if (rproc->auto_boot) {
ret = rproc_trigger_auto_boot(rproc);
--
Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
On Mon 17 May 15:45 CDT 2021, Siddharth Gupta wrote:
> When cdev_add is called after device_add has been called there is no
> way for the userspace to know about the addition of a cdev as cdev_add
> itself doesn't trigger a uevent notification, or for the kernel to
> know about the change to devt. This results in two problems:
> - mknod is never called for the cdev and hence no cdev appears on
> devtmpfs.
> - sysfs links to the new cdev are not established.
>
> The cdev needs to be added and devt assigned before device_add() is
> called in order for the relevant sysfs and devtmpfs entries to be
> created and the uevent to be properly populated.
>
Reviewed-by: Bjorn Andersson <[email protected]>
Regards,
Bjorn
> Signed-off-by: Siddharth Gupta <[email protected]>
> ---
> drivers/remoteproc/remoteproc_core.c | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> index 626a6b90f..562355a 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -2316,6 +2316,11 @@ int rproc_add(struct rproc *rproc)
> struct device *dev = &rproc->dev;
> int ret;
>
> + /* add char device for this remoteproc */
> + ret = rproc_char_device_add(rproc);
> + if (ret < 0)
> + return ret;
> +
> ret = device_add(dev);
> if (ret < 0)
> return ret;
> @@ -2329,11 +2334,6 @@ int rproc_add(struct rproc *rproc)
> /* create debugfs entries */
> rproc_create_debug_dir(rproc);
>
> - /* add char device for this remoteproc */
> - ret = rproc_char_device_add(rproc);
> - if (ret < 0)
> - return ret;
> -
> /* if rproc is marked always-on, request it to boot */
> if (rproc->auto_boot) {
> ret = rproc_trigger_auto_boot(rproc);
> --
> Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>