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From: Jens Wiklander <jens.wiklander@linaro.org>
To: linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	op-tee@lists.trustedfirmware.org, devicetree@vger.kernel.org,
	linux-doc@vger.kernel.org
Cc: Jerome Forissier <jerome@forissier.org>,
	Etienne Carriere <etienne.carriere@linaro.org>,
	Sumit Garg <sumit.garg@linaro.org>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Rob Herring <robh+dt@kernel.org>,
	Jonathan Corbet <corbet@lwn.net>,
	Ard Biesheuvel <ardb@kernel.org>, Marc Zyngier <maz@kernel.org>,
	Jens Wiklander <jens.wiklander@linaro.org>
Subject: [PATCH v2 5/7] tee: add tee_dev_open_helper() primitive
Date: Wed, 16 Jun 2021 12:36:47 +0200	[thread overview]
Message-ID: <20210616103649.2662395-6-jens.wiklander@linaro.org> (raw)
In-Reply-To: <20210616103649.2662395-1-jens.wiklander@linaro.org>

Adds tee_dev_open_helper() and tee_dev_ctx_put() to make it easier to
create a driver internal struct tee_context without the usual
tee_device_get() on the struct tee_device as that adds a circular
reference counter dependency and would prevent the struct tee_device
from ever being released again.

Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
---
 drivers/tee/tee_core.c  | 33 ++++++++++++++++++++++++---------
 include/linux/tee_drv.h | 27 +++++++++++++++++++++++++++
 2 files changed, 51 insertions(+), 9 deletions(-)

diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c
index f97d95b50773..6d81f6268b99 100644
--- a/drivers/tee/tee_core.c
+++ b/drivers/tee/tee_core.c
@@ -43,14 +43,11 @@ static DEFINE_SPINLOCK(driver_lock);
 static struct class *tee_class;
 static dev_t tee_devt;
 
-static struct tee_context *teedev_open(struct tee_device *teedev)
+struct tee_context *tee_dev_open_helper(struct tee_device *teedev)
 {
 	int rc;
 	struct tee_context *ctx;
 
-	if (!tee_device_get(teedev))
-		return ERR_PTR(-EINVAL);
-
 	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
 	if (!ctx) {
 		rc = -ENOMEM;
@@ -66,10 +63,30 @@ static struct tee_context *teedev_open(struct tee_device *teedev)
 	return ctx;
 err:
 	kfree(ctx);
-	tee_device_put(teedev);
 	return ERR_PTR(rc);
 
 }
+EXPORT_SYMBOL_GPL(tee_dev_open_helper);
+
+void tee_dev_ctx_put(struct tee_context *ctx)
+{
+	teedev_ctx_put(ctx);
+}
+EXPORT_SYMBOL_GPL(tee_dev_ctx_put);
+
+static struct tee_context *teedev_open(struct tee_device *teedev)
+{
+	struct tee_context *ctx;
+
+	if (!tee_device_get(teedev))
+		return ERR_PTR(-EINVAL);
+
+	ctx = tee_dev_open_helper(teedev);
+	if (IS_ERR(ctx))
+		tee_device_put(teedev);
+
+	return ctx;
+}
 
 void teedev_ctx_get(struct tee_context *ctx)
 {
@@ -90,10 +107,8 @@ static void teedev_ctx_release(struct kref *ref)
 
 void teedev_ctx_put(struct tee_context *ctx)
 {
-	if (ctx->releasing)
-		return;
-
-	kref_put(&ctx->refcount, teedev_ctx_release);
+	if (ctx && !ctx->releasing)
+		kref_put(&ctx->refcount, teedev_ctx_release);
 }
 
 static void teedev_close_context(struct tee_context *ctx)
diff --git a/include/linux/tee_drv.h b/include/linux/tee_drv.h
index 54269e47ac9a..f592ba4e9561 100644
--- a/include/linux/tee_drv.h
+++ b/include/linux/tee_drv.h
@@ -456,6 +456,33 @@ static inline int tee_shm_get_id(struct tee_shm *shm)
  */
 struct tee_shm *tee_shm_get_from_id(struct tee_context *ctx, int id);
 
+/**
+ * tee_dev_open_helper() - helper function to make a struct tee_context
+ * @teedev:	Device to open
+ *
+ * Creates the struct tee_context without increasing the reference counter
+ * on @teedev. This is needed for instance when a driver need an internal
+ * struct tee_context to operate on. By skipping the reference counter
+ * the circular dependency is broken.
+ *
+ * Note that this struct tee_context need special care when freeing in
+ * order to avoid the normal put on the struct tee_device.
+ * tee_dev_ctx_put() is the best choice for this.
+ *
+ * @returns a pointer 'struct tee_context' on success or an ERR_PTR on failure
+ */
+struct tee_context *tee_dev_open_helper(struct tee_device *teedev);
+
+/**
+ * tee_dev_ctx_put() - helper function to release a struct tee_context
+ * @ctx:	The struct tee_context to release
+ *
+ * Note that this function doesn't do a tee_device_put() on the internal
+ * struct tee_device so this function should normal only be used when
+ * releasing a struct tee_context obtained with tee_dev_open_helper().
+ */
+void tee_dev_ctx_put(struct tee_context *ctx);
+
 /**
  * tee_client_open_context() - Open a TEE context
  * @start:	if not NULL, continue search after this context
-- 
2.31.1


WARNING: multiple messages have this Message-ID
From: Jens Wiklander <jens.wiklander@linaro.org>
To: linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	op-tee@lists.trustedfirmware.org, devicetree@vger.kernel.org,
	linux-doc@vger.kernel.org
Cc: Jerome Forissier <jerome@forissier.org>,
	Etienne Carriere <etienne.carriere@linaro.org>,
	Sumit Garg <sumit.garg@linaro.org>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Rob Herring <robh+dt@kernel.org>,
	Jonathan Corbet <corbet@lwn.net>,
	Ard Biesheuvel <ardb@kernel.org>, Marc Zyngier <maz@kernel.org>,
	Jens Wiklander <jens.wiklander@linaro.org>
Subject: [PATCH v2 5/7] tee: add tee_dev_open_helper() primitive
Date: Wed, 16 Jun 2021 12:36:47 +0200	[thread overview]
Message-ID: <20210616103649.2662395-6-jens.wiklander@linaro.org> (raw)
In-Reply-To: <20210616103649.2662395-1-jens.wiklander@linaro.org>

Adds tee_dev_open_helper() and tee_dev_ctx_put() to make it easier to
create a driver internal struct tee_context without the usual
tee_device_get() on the struct tee_device as that adds a circular
reference counter dependency and would prevent the struct tee_device
from ever being released again.

Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
---
 drivers/tee/tee_core.c  | 33 ++++++++++++++++++++++++---------
 include/linux/tee_drv.h | 27 +++++++++++++++++++++++++++
 2 files changed, 51 insertions(+), 9 deletions(-)

diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c
index f97d95b50773..6d81f6268b99 100644
--- a/drivers/tee/tee_core.c
+++ b/drivers/tee/tee_core.c
@@ -43,14 +43,11 @@ static DEFINE_SPINLOCK(driver_lock);
 static struct class *tee_class;
 static dev_t tee_devt;
 
-static struct tee_context *teedev_open(struct tee_device *teedev)
+struct tee_context *tee_dev_open_helper(struct tee_device *teedev)
 {
 	int rc;
 	struct tee_context *ctx;
 
-	if (!tee_device_get(teedev))
-		return ERR_PTR(-EINVAL);
-
 	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
 	if (!ctx) {
 		rc = -ENOMEM;
@@ -66,10 +63,30 @@ static struct tee_context *teedev_open(struct tee_device *teedev)
 	return ctx;
 err:
 	kfree(ctx);
-	tee_device_put(teedev);
 	return ERR_PTR(rc);
 
 }
+EXPORT_SYMBOL_GPL(tee_dev_open_helper);
+
+void tee_dev_ctx_put(struct tee_context *ctx)
+{
+	teedev_ctx_put(ctx);
+}
+EXPORT_SYMBOL_GPL(tee_dev_ctx_put);
+
+static struct tee_context *teedev_open(struct tee_device *teedev)
+{
+	struct tee_context *ctx;
+
+	if (!tee_device_get(teedev))
+		return ERR_PTR(-EINVAL);
+
+	ctx = tee_dev_open_helper(teedev);
+	if (IS_ERR(ctx))
+		tee_device_put(teedev);
+
+	return ctx;
+}
 
 void teedev_ctx_get(struct tee_context *ctx)
 {
@@ -90,10 +107,8 @@ static void teedev_ctx_release(struct kref *ref)
 
 void teedev_ctx_put(struct tee_context *ctx)
 {
-	if (ctx->releasing)
-		return;
-
-	kref_put(&ctx->refcount, teedev_ctx_release);
+	if (ctx && !ctx->releasing)
+		kref_put(&ctx->refcount, teedev_ctx_release);
 }
 
 static void teedev_close_context(struct tee_context *ctx)
diff --git a/include/linux/tee_drv.h b/include/linux/tee_drv.h
index 54269e47ac9a..f592ba4e9561 100644
--- a/include/linux/tee_drv.h
+++ b/include/linux/tee_drv.h
@@ -456,6 +456,33 @@ static inline int tee_shm_get_id(struct tee_shm *shm)
  */
 struct tee_shm *tee_shm_get_from_id(struct tee_context *ctx, int id);
 
+/**
+ * tee_dev_open_helper() - helper function to make a struct tee_context
+ * @teedev:	Device to open
+ *
+ * Creates the struct tee_context without increasing the reference counter
+ * on @teedev. This is needed for instance when a driver need an internal
+ * struct tee_context to operate on. By skipping the reference counter
+ * the circular dependency is broken.
+ *
+ * Note that this struct tee_context need special care when freeing in
+ * order to avoid the normal put on the struct tee_device.
+ * tee_dev_ctx_put() is the best choice for this.
+ *
+ * @returns a pointer 'struct tee_context' on success or an ERR_PTR on failure
+ */
+struct tee_context *tee_dev_open_helper(struct tee_device *teedev);
+
+/**
+ * tee_dev_ctx_put() - helper function to release a struct tee_context
+ * @ctx:	The struct tee_context to release
+ *
+ * Note that this function doesn't do a tee_device_put() on the internal
+ * struct tee_device so this function should normal only be used when
+ * releasing a struct tee_context obtained with tee_dev_open_helper().
+ */
+void tee_dev_ctx_put(struct tee_context *ctx);
+
 /**
  * tee_client_open_context() - Open a TEE context
  * @start:	if not NULL, continue search after this context
-- 
2.31.1


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2021-06-16 10:37 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-16 10:36 [PATCH v2 0/7] Asynchronous notifications from secure world Jens Wiklander
2021-06-16 10:36 ` [PATCH v2 1/7] docs: staging/tee.rst: add a section on OP-TEE notifications Jens Wiklander
2021-06-16 10:36 ` [PATCH v2 2/7] dt-bindings: arm: Convert optee binding to json-schema Jens Wiklander
2021-06-16 16:03   ` Rob Herring
2021-06-16 16:05   ` Rob Herring
2021-06-22  8:38     ` Jens Wiklander
2021-06-16 10:36 ` [PATCH v2 3/7] dt-bindings: arm: optee: add interrupt property Jens Wiklander
2021-06-16 16:05   ` Rob Herring
2021-06-22  8:41     ` Jens Wiklander
2021-06-16 10:36 ` [PATCH v2 4/7] tee: fix put order in teedev_close_context() Jens Wiklander
2021-06-16 10:36 ` Jens Wiklander [this message]
2021-06-16 10:36 ` [PATCH v2 6/7] optee: separate notification functions Jens Wiklander
2021-06-16 10:36 ` [PATCH v2 7/7] optee: add asynchronous notifications Jens Wiklander
2021-06-16 14:08   ` Ard Biesheuvel
2021-06-17  4:33 ` [PATCH v2 0/7] Asynchronous notifications from secure world Sumit Garg
2021-06-17  6:10   ` Jens Wiklander
2021-07-06  7:25     ` Sumit Garg
2021-07-06 10:36       ` Marc Zyngier
2021-07-06 11:39         ` Sumit Garg
2021-07-06 12:46           ` Marc Zyngier
2021-07-07  5:52             ` Sumit Garg
2021-07-07  6:54               ` Jens Wiklander
2021-07-07 17:51               ` Sudeep Holla
2021-07-08 12:56                 ` Sumit Garg

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