[PATCH v4 0/4] remoteproc: core: Fixes for rproc cdev and add

[PATCH v4 0/4] remoteproc: core: Fixes for rproc cdev and add

[Siddharth Gupta]

This patch series contains stability fixes and error handling for remoteproc.

The changes included in this series do the following:
Patch 1: Fixes the creation of the rproc character device.
Patch 2: Validates rproc as the first step of rproc_add().
Patch 3: Fixes rproc cdev remove and the order of dev_del() and cdev_del().
Patch 4: Adds error handling in rproc_add().

v3 -> v4:
- Moved stable from CC to CC in sign-off area.

v2 -> v3:
- Removed extra file that got added by mistake.

v1 -> v2:
- Added extra patch which addresses Bjorn's comments on patch 3
  from v1.
- Fixed commit text for patch 2 (s/calling making/making).

Siddharth Gupta (4):
  remoteproc: core: Move cdev add before device add
  remoteproc: core: Move validate before device add
  remoteproc: core: Fix cdev remove and rproc del
  remoteproc: core: Cleanup device in case of failure

 drivers/remoteproc/remoteproc_cdev.c |  2 +-
 drivers/remoteproc/remoteproc_core.c | 27 ++++++++++++++++++---------
 2 files changed, 19 insertions(+), 10 deletions(-)

-- 
Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

[PATCH v4 1/4] remoteproc: core: Move cdev add before device add

[Siddharth Gupta]

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 <sidgup@codeaurora.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: stable@vger.kernel.org
---
 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 6348aaa..9ad8c5f 100644
--- a/drivers/remoteproc/remoteproc_core.c
+++ b/drivers/remoteproc/remoteproc_core.c
@@ -2333,6 +2333,11 @@ 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;
@@ -2346,11 +2351,6 @@ 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

[PATCH v4 2/4] remoteproc: core: Move validate before device add

[Siddharth Gupta]

We can validate whether the remoteproc is correctly setup before
making the cdev_add and device_add calls. This saves us the
trouble of cleaning up later on.

Signed-off-by: Siddharth Gupta <sidgup@codeaurora.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: stable@vger.kernel.org
---
 drivers/remoteproc/remoteproc_core.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
index 9ad8c5f..b65fce3 100644
--- a/drivers/remoteproc/remoteproc_core.c
+++ b/drivers/remoteproc/remoteproc_core.c
@@ -2333,16 +2333,16 @@ 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);
+	ret = rproc_validate(rproc);
 	if (ret < 0)
 		return ret;
 
-	ret = device_add(dev);
+	/* add char device for this remoteproc */
+	ret = rproc_char_device_add(rproc);
 	if (ret < 0)
 		return ret;
 
-	ret = rproc_validate(rproc);
+	ret = device_add(dev);
 	if (ret < 0)
 		return ret;
 
-- 
Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [PATCH v4 2/4] remoteproc: core: Move validate before device add

[Greg KH]

On Tue, Jun 15, 2021 at 12:03:42PM -0700, Siddharth Gupta wrote:
> We can validate whether the remoteproc is correctly setup before
> making the cdev_add and device_add calls. This saves us the
> trouble of cleaning up later on.
> 
> Signed-off-by: Siddharth Gupta <sidgup@codeaurora.org>
> Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
> Cc: stable@vger.kernel.org
> ---
>  drivers/remoteproc/remoteproc_core.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 

Why is this relevant for stable?  What commit does this fix?  Please put
a Fixes: tag for that.

thanks,

greg k-h

[PATCH v4 3/4] remoteproc: core: Fix cdev remove and rproc del

[Siddharth Gupta]

The rproc_char_device_remove() call currently unmaps the cdev
region instead of simply deleting the cdev that was added as a
part of the rproc_char_device_add() call. This change fixes that
behaviour, and also fixes the order in which device_del() and
cdev_del() need to be called.

Signed-off-by: Siddharth Gupta <sidgup@codeaurora.org>
Cc: stable@vger.kernel.org
---
 drivers/remoteproc/remoteproc_cdev.c | 2 +-
 drivers/remoteproc/remoteproc_core.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/remoteproc/remoteproc_cdev.c b/drivers/remoteproc/remoteproc_cdev.c
index 0b8a84c..4ad98b0 100644
--- a/drivers/remoteproc/remoteproc_cdev.c
+++ b/drivers/remoteproc/remoteproc_cdev.c
@@ -124,7 +124,7 @@ int rproc_char_device_add(struct rproc *rproc)
 
 void rproc_char_device_remove(struct rproc *rproc)
 {
-	__unregister_chrdev(MAJOR(rproc->dev.devt), rproc->index, 1, "remoteproc");
+	cdev_del(&rproc->cdev);
 }
 
 void __init rproc_init_cdev(void)
diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
index b65fce3..b874280 100644
--- a/drivers/remoteproc/remoteproc_core.c
+++ b/drivers/remoteproc/remoteproc_core.c
@@ -2619,7 +2619,6 @@ int rproc_del(struct rproc *rproc)
 	mutex_unlock(&rproc->lock);
 
 	rproc_delete_debug_dir(rproc);
-	rproc_char_device_remove(rproc);
 
 	/* the rproc is downref'ed as soon as it's removed from the klist */
 	mutex_lock(&rproc_list_mutex);
@@ -2630,6 +2629,7 @@ int rproc_del(struct rproc *rproc)
 	synchronize_rcu();
 
 	device_del(&rproc->dev);
+	rproc_char_device_remove(rproc);
 
 	return 0;
 }
-- 
Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [PATCH v4 3/4] remoteproc: core: Fix cdev remove and rproc del

[Greg KH]

On Tue, Jun 15, 2021 at 12:03:43PM -0700, Siddharth Gupta wrote:
> The rproc_char_device_remove() call currently unmaps the cdev
> region instead of simply deleting the cdev that was added as a
> part of the rproc_char_device_add() call. This change fixes that
> behaviour, and also fixes the order in which device_del() and
> cdev_del() need to be called.
> 
> Signed-off-by: Siddharth Gupta <sidgup@codeaurora.org>
> Cc: stable@vger.kernel.org

Is this really needed for stable?  What bug does this solve?  ANd again,
fixes: ?

[PATCH v4 4/4] remoteproc: core: Cleanup device in case of failure

[Siddharth Gupta]

When a failure occurs in rproc_add() it returns an error, but does
not cleanup after itself. This change adds the failure path in such
cases.

Signed-off-by: Siddharth Gupta <sidgup@codeaurora.org>
Cc: stable@vger.kernel.org
---
 drivers/remoteproc/remoteproc_core.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
index b874280..d823f70 100644
--- a/drivers/remoteproc/remoteproc_core.c
+++ b/drivers/remoteproc/remoteproc_core.c
@@ -2343,8 +2343,10 @@ int rproc_add(struct rproc *rproc)
 		return ret;
 
 	ret = device_add(dev);
-	if (ret < 0)
-		return ret;
+	if (ret < 0) {
+		put_device(dev);
+		goto rproc_remove_cdev;
+	}
 
 	dev_info(dev, "%s is available\n", rproc->name);
 
@@ -2355,7 +2357,7 @@ int rproc_add(struct rproc *rproc)
 	if (rproc->auto_boot) {
 		ret = rproc_trigger_auto_boot(rproc);
 		if (ret < 0)
-			return ret;
+			goto rproc_remove_dev;
 	}
 
 	/* expose to rproc_get_by_phandle users */
@@ -2364,6 +2366,13 @@ int rproc_add(struct rproc *rproc)
 	mutex_unlock(&rproc_list_mutex);
 
 	return 0;
+
+rproc_remove_dev:
+	rproc_delete_debug_dir(rproc);
+	device_del(dev);
+rproc_remove_cdev:
+	rproc_char_device_remove(rproc);
+	return ret;
 }
 EXPORT_SYMBOL(rproc_add);
 
-- 
Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [PATCH v4 4/4] remoteproc: core: Cleanup device in case of failure

[Greg KH]

On Tue, Jun 15, 2021 at 12:03:44PM -0700, Siddharth Gupta wrote:
> When a failure occurs in rproc_add() it returns an error, but does
> not cleanup after itself. This change adds the failure path in such
> cases.
> 
> Signed-off-by: Siddharth Gupta <sidgup@codeaurora.org>
> Cc: stable@vger.kernel.org
> ---
>  drivers/remoteproc/remoteproc_core.c | 15 ++++++++++++---
>  1 file changed, 12 insertions(+), 3 deletions(-)

Why is this needed for stable kernels?  And again, a Fixes: tag?

Re: [PATCH v4 4/4] remoteproc: core: Cleanup device in case of failure

[Siddharth Gupta]

On 6/15/2021 12:06 PM, Greg KH wrote:
> On Tue, Jun 15, 2021 at 12:03:44PM -0700, Siddharth Gupta wrote:
>> When a failure occurs in rproc_add() it returns an error, but does
>> not cleanup after itself. This change adds the failure path in such
>> cases.
>>
>> Signed-off-by: Siddharth Gupta <sidgup@codeaurora.org>
>> Cc: stable@vger.kernel.org
>> ---
>>   drivers/remoteproc/remoteproc_core.c | 15 ++++++++++++---
>>   1 file changed, 12 insertions(+), 3 deletions(-)
> Why is this needed for stable kernels?  And again, a Fixes: tag?
Patch 2 and patch 3 are leading up to fix rproc_add()
in case of a failure. This means we'll have errors with
use after free unless we call device_del() or cdev_del(),
also the sysfs and devtempfs nodes will also not be
removed.

Thanks,
Sid

Re: [PATCH v4 4/4] remoteproc: core: Cleanup device in case of failure

[Greg KH]

On Tue, Jun 15, 2021 at 01:21:11PM -0700, Siddharth Gupta wrote:
> 
> On 6/15/2021 12:06 PM, Greg KH wrote:
> > On Tue, Jun 15, 2021 at 12:03:44PM -0700, Siddharth Gupta wrote:
> > > When a failure occurs in rproc_add() it returns an error, but does
> > > not cleanup after itself. This change adds the failure path in such
> > > cases.
> > > 
> > > Signed-off-by: Siddharth Gupta <sidgup@codeaurora.org>
> > > Cc: stable@vger.kernel.org
> > > ---
> > >   drivers/remoteproc/remoteproc_core.c | 15 ++++++++++++---
> > >   1 file changed, 12 insertions(+), 3 deletions(-)
> > Why is this needed for stable kernels?  And again, a Fixes: tag?
> Patch 2 and patch 3 are leading up to fix rproc_add()
> in case of a failure. This means we'll have errors with
> use after free unless we call device_del() or cdev_del(),
> also the sysfs and devtempfs nodes will also not be
> removed.

Then please explain that better in the changelogs.  At it is, no one
knows this.

greg k-h