[PATCH v2 0/4] remoteproc: core: Fixes for rproc cdev and add

[PATCH v2 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 the rproc cdev remove and the order of dev_del() and cdev_del().
Patch 4: Adds error handling in rproc_add().

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

 0000-cover-letter.patch.backup       | 26 ++++++++++++++++++++++++++
 drivers/remoteproc/remoteproc_cdev.c |  2 +-
 drivers/remoteproc/remoteproc_core.c | 27 ++++++++++++++++++---------
 3 files changed, 45 insertions(+), 10 deletions(-)
 create mode 100644 0000-cover-letter.patch.backup

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

[PATCH v2 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>
---
 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 v2 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>
---
 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

[PATCH v2 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>
---
 0000-cover-letter.patch.backup       | 26 ++++++++++++++++++++++++++
 drivers/remoteproc/remoteproc_cdev.c |  2 +-
 drivers/remoteproc/remoteproc_core.c |  2 +-
 3 files changed, 28 insertions(+), 2 deletions(-)
 create mode 100644 0000-cover-letter.patch.backup

diff --git a/0000-cover-letter.patch.backup b/0000-cover-letter.patch.backup
new file mode 100644
index 0000000..837bcdb
--- /dev/null
+++ b/0000-cover-letter.patch.backup
@@ -0,0 +1,26 @@
+From 78fcb27d574d2f7b06e37b77b257f98858a88d9d Mon Sep 17 00:00:00 2001
+From: Siddharth Gupta <sidgup@codeaurora.org>
+Date: Mon, 17 May 2021 13:33:25 -0700
+Subject: [PATCH 0/3] remoteproc: core: Fixes for rproc cdev and add
+To: bjorn.andersson@linaro.org,ohad@wizery.com,linux-remoteproc@vger.kernel.org
+Cc: linux-kernel@vger.kernel.org,linux-arm-msm@vger.kernel.org,linux-arm-kernel@lists.infradead.org,psodagud@codeaurora.org,stable@vger.kernel.org
+
+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: Adds error handling in rproc_add().
+
+Siddharth Gupta (3):
+  remoteproc: core: Move cdev add before device add
+  remoteproc: core: Move validate before device add
+  remoteproc: core: Cleanup device in case of failure
+
+ drivers/remoteproc/remoteproc_core.c | 25 +++++++++++++++++--------
+ 1 file changed, 17 insertions(+), 8 deletions(-)
+
+-- 
+Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
+a Linux Foundation Collaborative Project
+
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

[PATCH v2 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>
---
 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 v2 0/4] remoteproc: core: Fixes for rproc cdev and add

[Bjorn Andersson]

On Mon 14 Jun 15:40 CDT 2021, Siddharth Gupta wrote:

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

Thanks for respinning this Sid, I think patch 3 looks good now as well,
but it seems you accidentally got an additional file in the same patch.

Can you please fix that up and resend the patches?

Regards,
Bjorn

> 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 the rproc cdev remove and the order of dev_del() and cdev_del().
> Patch 4: Adds error handling in rproc_add().
> 
> 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
> 
>  0000-cover-letter.patch.backup       | 26 ++++++++++++++++++++++++++
>  drivers/remoteproc/remoteproc_cdev.c |  2 +-
>  drivers/remoteproc/remoteproc_core.c | 27 ++++++++++++++++++---------
>  3 files changed, 45 insertions(+), 10 deletions(-)
>  create mode 100644 0000-cover-letter.patch.backup
> 
> -- 
> Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>