[PATCH v4 0/2] tpm: add support for nonblocking operation

[PATCH v4 0/2] tpm: add support for nonblocking operation

[Tadeusz Struk]

The TCG SAPI specification [1] defines a set of functions, which allow
applications to use the TPM device in either blocking or non-blocking fashion.
Each command defined by the specification has a corresponding
Tss2_Sys_<COMMAND>_Prepare() and Tss2_Sys_<COMMAND>_Complete() call, which
together with Tss2_Sys_ExecuteAsync() is designed to allow asynchronous
mode of operation. Currently the TPM driver supports only blocking calls,
which doesn't allow asynchronous IO operations.
This patch changes it and adds support for nonblocking write and a new poll
function to enable applications, which want to take advantage of this feature.
The new functionality can be tested using standard TPM tools implemented
in [2], together with modified TCTI from [3], and an example application
by Philip Tricca [4]. Here is a short description from Philip:

"The example application `glib-tss2-event` uses a glib main event loop
to create an RSA 2048 primary key in the TPM2 NULL hierarchy while
using a glib timer event to time the operation. A GSource object is
used to generate an event when the FD underlying the tss2 function
call has data ready. While the application waits for an event indicating
that the CreatePrimary operation is complete, it counts timer events
that occur every 100ms. Once the CreatePrimary operation completes the
number of timer events that occurred is used to make a rough calculation
of the elapsed time. This value is then printed to the console.
This takes ~300 lines of C code and requires no management or
synchronization of threads. The glib GMainContext is "just a poll()
loop" according to the glib documentation here:

https://developer.gnome.org/programming-guidelines/stable/main-contexts.html.en

and so supporting 'poll' is the easiest way to integrate with glib /
gtk+. This is true of any other event system that relies on 'poll'
instead of worker threads."

[1] https://trustedcomputinggroup.org/wp-content/uploads/TSS_SAPI_Version-1.1_Revision-22_review_030918.pdf
[2] https://github.com/tpm2-software/tpm2-tools
[3] https://github.com/tstruk/tpm2-tss/tree/async
[4] https://github.com/flihp/glib-tss2-async-example

---
Changes in v4:
- Changed the way buffer_mutex is handled in nonblocking mode so that
  it is not held when write() returns to user space.

Changes in v3:
- Fixed problem reported by 0-dey kbuild test robot around __exitcall.
  It complained because there is a module_exit() in another file already.
- Added info on example application from Philip

Changes in v2:
- Split the change into two separate patches. First patch adds a pointer
  to the space to the struct file_priv to have access to it from the async job.
  This is to avoid memory allocations on every write call. Now everything
  what's needed is in the file_priv struct.
- Renamed the 'work' member of the timer to avoid confusion.
  Now there are 'timeout_work' and 'async_work'.
- Removed the global wait queue and moved it to file_priv.
- Only creating the work queue when the first file is opened.

Tadeusz Struk (2):
      tpm: add ptr to the tpm_space struct to file_priv
      tpm: add support for nonblocking operation

 drivers/char/tpm/tpm-dev-common.c |  150 +++++++++++++++++++++++++++----------
 drivers/char/tpm/tpm-dev.c        |   22 +++--
 drivers/char/tpm/tpm-dev.h        |   19 +++--
 drivers/char/tpm/tpm-interface.c  |    1 
 drivers/char/tpm/tpm.h            |    1 
 drivers/char/tpm/tpmrm-dev.c      |   31 ++++----
 6 files changed, 152 insertions(+), 72 deletions(-)

--
TS

[PATCH v4 1/2] tpm: add ptr to the tpm_space struct to file_priv

[Tadeusz Struk]

Add a ptr to struct tpm_space to the file_priv to have an easy
access to it in the async job without the need to allocate memory.
This also allows to consolidate of the write operations for
the two interfaces.

Tested-by: Philip Tricca <philip.b.tricca@intel.com>
Signed-off-by: Tadeusz Struk <tadeusz.struk@intel.com>
---
 drivers/char/tpm/tpm-dev-common.c |    8 +++++---
 drivers/char/tpm/tpm-dev.c        |   10 ++--------
 drivers/char/tpm/tpm-dev.h        |    5 +++--
 drivers/char/tpm/tpmrm-dev.c      |   14 ++------------
 4 files changed, 12 insertions(+), 25 deletions(-)

diff --git a/drivers/char/tpm/tpm-dev-common.c b/drivers/char/tpm/tpm-dev-common.c
index e4a04b2d3c32..f0c033b69b62 100644
--- a/drivers/char/tpm/tpm-dev-common.c
+++ b/drivers/char/tpm/tpm-dev-common.c
@@ -43,9 +43,11 @@ static void timeout_work(struct work_struct *work)
 }
 
 void tpm_common_open(struct file *file, struct tpm_chip *chip,
-		     struct file_priv *priv)
+		     struct file_priv *priv, struct tpm_space *space)
 {
 	priv->chip = chip;
+	priv->space = space;
+
 	mutex_init(&priv->buffer_mutex);
 	timer_setup(&priv->user_read_timer, user_reader_timeout, 0);
 	INIT_WORK(&priv->work, timeout_work);
@@ -79,7 +81,7 @@ ssize_t tpm_common_read(struct file *file, char __user *buf,
 }
 
 ssize_t tpm_common_write(struct file *file, const char __user *buf,
-			 size_t size, loff_t *off, struct tpm_space *space)
+			 size_t size, loff_t *off)
 {
 	struct file_priv *priv = file->private_data;
 	size_t in_size = size;
@@ -119,7 +121,7 @@ ssize_t tpm_common_write(struct file *file, const char __user *buf,
 		mutex_unlock(&priv->buffer_mutex);
 		return -EPIPE;
 	}
-	out_size = tpm_transmit(priv->chip, space, priv->data_buffer,
+	out_size = tpm_transmit(priv->chip, priv->space, priv->data_buffer,
 				sizeof(priv->data_buffer), 0);
 
 	tpm_put_ops(priv->chip);
diff --git a/drivers/char/tpm/tpm-dev.c b/drivers/char/tpm/tpm-dev.c
index ebd74ab5abef..98b9630c3a36 100644
--- a/drivers/char/tpm/tpm-dev.c
+++ b/drivers/char/tpm/tpm-dev.c
@@ -39,7 +39,7 @@ static int tpm_open(struct inode *inode, struct file *file)
 	if (priv == NULL)
 		goto out;
 
-	tpm_common_open(file, chip, priv);
+	tpm_common_open(file, chip, priv, NULL);
 
 	return 0;
 
@@ -48,12 +48,6 @@ static int tpm_open(struct inode *inode, struct file *file)
 	return -ENOMEM;
 }
 
-static ssize_t tpm_write(struct file *file, const char __user *buf,
-			 size_t size, loff_t *off)
-{
-	return tpm_common_write(file, buf, size, off, NULL);
-}
-
 /*
  * Called on file close
  */
@@ -73,6 +67,6 @@ const struct file_operations tpm_fops = {
 	.llseek = no_llseek,
 	.open = tpm_open,
 	.read = tpm_common_read,
-	.write = tpm_write,
+	.write = tpm_common_write,
 	.release = tpm_release,
 };
diff --git a/drivers/char/tpm/tpm-dev.h b/drivers/char/tpm/tpm-dev.h
index b24cfb4d3ee1..4048677bbd78 100644
--- a/drivers/char/tpm/tpm-dev.h
+++ b/drivers/char/tpm/tpm-dev.h
@@ -6,6 +6,7 @@
 
 struct file_priv {
 	struct tpm_chip *chip;
+	struct tpm_space *space;
 
 	/* Data passed to and from the tpm via the read/write calls */
 	size_t data_pending;
@@ -18,11 +19,11 @@ struct file_priv {
 };
 
 void tpm_common_open(struct file *file, struct tpm_chip *chip,
-		     struct file_priv *priv);
+		     struct file_priv *priv, struct tpm_space *space);
 ssize_t tpm_common_read(struct file *file, char __user *buf,
 			size_t size, loff_t *off);
 ssize_t tpm_common_write(struct file *file, const char __user *buf,
-			 size_t size, loff_t *off, struct tpm_space *space);
+			 size_t size, loff_t *off);
 void tpm_common_release(struct file *file, struct file_priv *priv);
 
 #endif
diff --git a/drivers/char/tpm/tpmrm-dev.c b/drivers/char/tpm/tpmrm-dev.c
index 1a0e97a5da5a..96006c6b9696 100644
--- a/drivers/char/tpm/tpmrm-dev.c
+++ b/drivers/char/tpm/tpmrm-dev.c
@@ -28,7 +28,7 @@ static int tpmrm_open(struct inode *inode, struct file *file)
 		return -ENOMEM;
 	}
 
-	tpm_common_open(file, chip, &priv->priv);
+	tpm_common_open(file, chip, &priv->priv, &priv->space);
 
 	return 0;
 }
@@ -45,21 +45,11 @@ static int tpmrm_release(struct inode *inode, struct file *file)
 	return 0;
 }
 
-static ssize_t tpmrm_write(struct file *file, const char __user *buf,
-		   size_t size, loff_t *off)
-{
-	struct file_priv *fpriv = file->private_data;
-	struct tpmrm_priv *priv = container_of(fpriv, struct tpmrm_priv, priv);
-
-	return tpm_common_write(file, buf, size, off, &priv->space);
-}
-
 const struct file_operations tpmrm_fops = {
 	.owner = THIS_MODULE,
 	.llseek = no_llseek,
 	.open = tpmrm_open,
 	.read = tpm_common_read,
-	.write = tpmrm_write,
+	.write = tpm_common_write,
 	.release = tpmrm_release,
 };
-

[PATCH v4 2/2] tpm: add support for nonblocking operation

[Tadeusz Struk]

Currently the TPM driver only supports blocking calls, which doesn't allow
asynchronous IO operations to the TPM hardware.
This patch changes it and adds support for nonblocking write and a new poll
function to enable applications, which want to take advantage of this.

Tested-by: Philip Tricca <philip.b.tricca@intel.com>
Signed-off-by: Tadeusz Struk <tadeusz.struk@intel.com>
---
 drivers/char/tpm/tpm-dev-common.c |  149 ++++++++++++++++++++++++++++---------
 drivers/char/tpm/tpm-dev.c        |   16 +++-
 drivers/char/tpm/tpm-dev.h        |   17 +++-
 drivers/char/tpm/tpm-interface.c  |    1 
 drivers/char/tpm/tpm.h            |    1 
 drivers/char/tpm/tpmrm-dev.c      |   19 +++--
 6 files changed, 150 insertions(+), 53 deletions(-)

diff --git a/drivers/char/tpm/tpm-dev-common.c b/drivers/char/tpm/tpm-dev-common.c
index f0c033b69b62..f71d80b94451 100644
--- a/drivers/char/tpm/tpm-dev-common.c
+++ b/drivers/char/tpm/tpm-dev-common.c
@@ -17,11 +17,36 @@
  * License.
  *
  */
+#include <linux/poll.h>
 #include <linux/slab.h>
 #include <linux/uaccess.h>
+#include <linux/workqueue.h>
 #include "tpm.h"
 #include "tpm-dev.h"
 
+static struct workqueue_struct *tpm_dev_wq;
+static DEFINE_MUTEX(tpm_dev_wq_lock);
+
+static void tpm_async_work(struct work_struct *work)
+{
+	struct file_priv *priv =
+			container_of(work, struct file_priv, async_work);
+	ssize_t ret;
+
+	mutex_lock(&priv->buffer_mutex);
+	priv->command_enqueued = false;
+	ret = tpm_transmit(priv->chip, priv->space, priv->data_buffer,
+			   sizeof(priv->data_buffer), 0);
+
+	tpm_put_ops(priv->chip);
+	if (ret > 0) {
+		priv->data_pending = ret;
+		mod_timer(&priv->user_read_timer, jiffies + (120 * HZ));
+	}
+	mutex_unlock(&priv->buffer_mutex);
+	wake_up_interruptible(&priv->async_wait);
+}
+
 static void user_reader_timeout(struct timer_list *t)
 {
 	struct file_priv *priv = from_timer(priv, t, user_read_timer);
@@ -29,30 +54,44 @@ static void user_reader_timeout(struct timer_list *t)
 	pr_warn("TPM user space timeout is deprecated (pid=%d)\n",
 		task_tgid_nr(current));
 
-	schedule_work(&priv->work);
+	schedule_work(&priv->timeout_work);
 }
 
-static void timeout_work(struct work_struct *work)
+static void tpm_timeout_work(struct work_struct *work)
 {
-	struct file_priv *priv = container_of(work, struct file_priv, work);
+	struct file_priv *priv = container_of(work, struct file_priv,
+					      timeout_work);
 
 	mutex_lock(&priv->buffer_mutex);
 	priv->data_pending = 0;
 	memset(priv->data_buffer, 0, sizeof(priv->data_buffer));
 	mutex_unlock(&priv->buffer_mutex);
+	wake_up_interruptible(&priv->async_wait);
 }
 
-void tpm_common_open(struct file *file, struct tpm_chip *chip,
-		     struct file_priv *priv, struct tpm_space *space)
+int tpm_common_open(struct file *file, struct tpm_chip *chip,
+		    struct file_priv *priv, struct tpm_space *space)
 {
 	priv->chip = chip;
 	priv->space = space;
 
 	mutex_init(&priv->buffer_mutex);
 	timer_setup(&priv->user_read_timer, user_reader_timeout, 0);
-	INIT_WORK(&priv->work, timeout_work);
-
+	INIT_WORK(&priv->timeout_work, tpm_timeout_work);
+	INIT_WORK(&priv->async_work, tpm_async_work);
+	init_waitqueue_head(&priv->async_wait);
 	file->private_data = priv;
+	mutex_lock(&tpm_dev_wq_lock);
+	if (!tpm_dev_wq) {
+		tpm_dev_wq = alloc_workqueue("tpm_dev_wq", WQ_MEM_RECLAIM, 0);
+		if (!tpm_dev_wq) {
+			mutex_unlock(&tpm_dev_wq_lock);
+			return -ENOMEM;
+		}
+	}
+
+	mutex_unlock(&tpm_dev_wq_lock);
+	return 0;
 }
 
 ssize_t tpm_common_read(struct file *file, char __user *buf,
@@ -63,15 +102,17 @@ ssize_t tpm_common_read(struct file *file, char __user *buf,
 	int rc;
 
 	del_singleshot_timer_sync(&priv->user_read_timer);
-	flush_work(&priv->work);
+	flush_work(&priv->timeout_work);
 	mutex_lock(&priv->buffer_mutex);
 
 	if (priv->data_pending) {
 		ret_size = min_t(ssize_t, size, priv->data_pending);
-		rc = copy_to_user(buf, priv->data_buffer, ret_size);
-		memset(priv->data_buffer, 0, priv->data_pending);
-		if (rc)
-			ret_size = -EFAULT;
+		if (ret_size > 0) {
+			rc = copy_to_user(buf, priv->data_buffer, ret_size);
+			memset(priv->data_buffer, 0, priv->data_pending);
+			if (rc)
+				ret_size = -EFAULT;
+		}
 
 		priv->data_pending = 0;
 	}
@@ -84,10 +125,9 @@ ssize_t tpm_common_write(struct file *file, const char __user *buf,
 			 size_t size, loff_t *off)
 {
 	struct file_priv *priv = file->private_data;
-	size_t in_size = size;
-	ssize_t out_size;
+	int ret = 0;
 
-	if (in_size > TPM_BUFSIZE)
+	if (size > TPM_BUFSIZE)
 		return -E2BIG;
 
 	mutex_lock(&priv->buffer_mutex);
@@ -96,21 +136,20 @@ ssize_t tpm_common_write(struct file *file, const char __user *buf,
 	 * tpm_read or a user_read_timer timeout. This also prevents split
 	 * buffered writes from blocking here.
 	 */
-	if (priv->data_pending != 0) {
-		mutex_unlock(&priv->buffer_mutex);
-		return -EBUSY;
+	if (priv->data_pending != 0 || priv->command_enqueued) {
+		ret = -EBUSY;
+		goto out;
 	}
 
-	if (copy_from_user
-	    (priv->data_buffer, (void __user *) buf, in_size)) {
-		mutex_unlock(&priv->buffer_mutex);
-		return -EFAULT;
+	if (copy_from_user(priv->data_buffer, buf, size)) {
+		ret = -EFAULT;
+		goto out;
 	}
 
-	if (in_size < 6 ||
-	    in_size < be32_to_cpu(*((__be32 *) (priv->data_buffer + 2)))) {
-		mutex_unlock(&priv->buffer_mutex);
-		return -EINVAL;
+	if (size < 6 ||
+	    size < be32_to_cpu(*((__be32 *)(priv->data_buffer + 2)))) {
+		ret = -EINVAL;
+		goto out;
 	}
 
 	/* atomic tpm command send and result receive. We only hold the ops
@@ -118,25 +157,50 @@ ssize_t tpm_common_write(struct file *file, const char __user *buf,
 	 * the char dev is held open.
 	 */
 	if (tpm_try_get_ops(priv->chip)) {
-		mutex_unlock(&priv->buffer_mutex);
-		return -EPIPE;
+		ret = -EPIPE;
+		goto out;
 	}
-	out_size = tpm_transmit(priv->chip, priv->space, priv->data_buffer,
-				sizeof(priv->data_buffer), 0);
 
-	tpm_put_ops(priv->chip);
-	if (out_size < 0) {
+	/*
+	 * If in nonblocking mode schedule an async job to send
+	 * the command return the size.
+	 * In case of error the err code will be returned in
+	 * the subsequent read call.
+	 */
+	if (file->f_flags & O_NONBLOCK) {
+		priv->command_enqueued = true;
+		queue_work(tpm_dev_wq, &priv->async_work);
 		mutex_unlock(&priv->buffer_mutex);
-		return out_size;
+		return size;
 	}
 
-	priv->data_pending = out_size;
+	ret = tpm_transmit(priv->chip, priv->space, priv->data_buffer,
+			   sizeof(priv->data_buffer), 0);
+	tpm_put_ops(priv->chip);
+
+	if (ret > 0) {
+		priv->data_pending = ret;
+		mod_timer(&priv->user_read_timer, jiffies + (120 * HZ));
+		ret = size;
+	}
+out:
 	mutex_unlock(&priv->buffer_mutex);
+	return ret;
+}
 
-	/* Set a timeout by which the reader must come claim the result */
-	mod_timer(&priv->user_read_timer, jiffies + (120 * HZ));
+__poll_t tpm_common_poll(struct file *file, poll_table *wait)
+{
+	struct file_priv *priv = file->private_data;
+	__poll_t mask = 0;
+
+	poll_wait(file, &priv->async_wait, wait);
 
-	return in_size;
+	if (priv->data_pending)
+		mask = EPOLLIN | EPOLLRDNORM;
+	else
+		mask = EPOLLOUT | EPOLLWRNORM;
+
+	return mask;
 }
 
 /*
@@ -144,8 +208,17 @@ ssize_t tpm_common_write(struct file *file, const char __user *buf,
  */
 void tpm_common_release(struct file *file, struct file_priv *priv)
 {
+	flush_work(&priv->async_work);
 	del_singleshot_timer_sync(&priv->user_read_timer);
-	flush_work(&priv->work);
+	flush_work(&priv->timeout_work);
 	file->private_data = NULL;
 	priv->data_pending = 0;
 }
+
+void __exit tpm_dev_common_exit(void)
+{
+	if (tpm_dev_wq) {
+		destroy_workqueue(tpm_dev_wq);
+		tpm_dev_wq = NULL;
+	}
+}
diff --git a/drivers/char/tpm/tpm-dev.c b/drivers/char/tpm/tpm-dev.c
index 98b9630c3a36..1e353a4f4b7e 100644
--- a/drivers/char/tpm/tpm-dev.c
+++ b/drivers/char/tpm/tpm-dev.c
@@ -24,6 +24,7 @@ static int tpm_open(struct inode *inode, struct file *file)
 {
 	struct tpm_chip *chip;
 	struct file_priv *priv;
+	int rc = -ENOMEM;
 
 	chip = container_of(inode->i_cdev, struct tpm_chip, cdev);
 
@@ -37,15 +38,21 @@ static int tpm_open(struct inode *inode, struct file *file)
 
 	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 	if (priv == NULL)
-		goto out;
+		goto out_clear;
 
-	tpm_common_open(file, chip, priv, NULL);
+	rc = tpm_common_open(file, chip, priv, NULL);
+	if (rc)
+		goto out_free;
 
 	return 0;
 
- out:
+out_free:
+	kfree(priv);
+
+out_clear:
 	clear_bit(0, &chip->is_open);
-	return -ENOMEM;
+
+	return rc;
 }
 
 /*
@@ -68,5 +75,6 @@ const struct file_operations tpm_fops = {
 	.open = tpm_open,
 	.read = tpm_common_read,
 	.write = tpm_common_write,
+	.poll = tpm_common_poll,
 	.release = tpm_release,
 };
diff --git a/drivers/char/tpm/tpm-dev.h b/drivers/char/tpm/tpm-dev.h
index 4048677bbd78..2f0aeff57002 100644
--- a/drivers/char/tpm/tpm-dev.h
+++ b/drivers/char/tpm/tpm-dev.h
@@ -2,28 +2,33 @@
 #ifndef _TPM_DEV_H
 #define _TPM_DEV_H
 
+#include <linux/poll.h>
 #include "tpm.h"
 
 struct file_priv {
 	struct tpm_chip *chip;
 	struct tpm_space *space;
 
-	/* Data passed to and from the tpm via the read/write calls */
-	size_t data_pending;
+	/* Holds the amount of data passed or an error code from async op */
+	ssize_t data_pending;
 	struct mutex buffer_mutex;
 
 	struct timer_list user_read_timer;      /* user needs to claim result */
-	struct work_struct work;
+	struct work_struct timeout_work;
+	struct work_struct async_work;
+	wait_queue_head_t async_wait;
+	bool command_enqueued;
 
 	u8 data_buffer[TPM_BUFSIZE];
 };
 
-void tpm_common_open(struct file *file, struct tpm_chip *chip,
-		     struct file_priv *priv, struct tpm_space *space);
+int tpm_common_open(struct file *file, struct tpm_chip *chip,
+		    struct file_priv *priv, struct tpm_space *space);
 ssize_t tpm_common_read(struct file *file, char __user *buf,
 			size_t size, loff_t *off);
 ssize_t tpm_common_write(struct file *file, const char __user *buf,
 			 size_t size, loff_t *off);
-void tpm_common_release(struct file *file, struct file_priv *priv);
+__poll_t tpm_common_poll(struct file *file, poll_table *wait);
 
+void tpm_common_release(struct file *file, struct file_priv *priv);
 #endif
diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 1a803b0cf980..9e3de6447512 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -1428,6 +1428,7 @@ static void __exit tpm_exit(void)
 	class_destroy(tpm_class);
 	class_destroy(tpmrm_class);
 	unregister_chrdev_region(tpm_devt, 2*TPM_NUM_DEVICES);
+	tpm_dev_common_exit();
 }
 
 subsys_initcall(tpm_init);
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index f3501d05264f..b909dc9e251f 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -604,4 +604,5 @@ int tpm2_commit_space(struct tpm_chip *chip, struct tpm_space *space,
 
 int tpm_bios_log_setup(struct tpm_chip *chip);
 void tpm_bios_log_teardown(struct tpm_chip *chip);
+void tpm_dev_common_exit(void);
 #endif
diff --git a/drivers/char/tpm/tpmrm-dev.c b/drivers/char/tpm/tpmrm-dev.c
index 96006c6b9696..f131c97c1577 100644
--- a/drivers/char/tpm/tpmrm-dev.c
+++ b/drivers/char/tpm/tpmrm-dev.c
@@ -23,14 +23,22 @@ static int tpmrm_open(struct inode *inode, struct file *file)
 		return -ENOMEM;
 
 	rc = tpm2_init_space(&priv->space);
-	if (rc) {
-		kfree(priv);
-		return -ENOMEM;
-	}
+	if (rc)
+		goto out_free;
 
-	tpm_common_open(file, chip, &priv->priv, &priv->space);
+	rc = tpm_common_open(file, chip, &priv->priv, &priv->space);
+	if (rc)
+		goto out_del_space;
 
 	return 0;
+
+out_del_space:
+	tpm2_del_space(chip, &priv->space);
+
+out_free:
+	kfree(priv);
+
+	return rc;
 }
 
 static int tpmrm_release(struct inode *inode, struct file *file)
@@ -51,5 +59,6 @@ const struct file_operations tpmrm_fops = {
 	.open = tpmrm_open,
 	.read = tpm_common_read,
 	.write = tpm_common_write,
+	.poll = tpm_common_poll,
 	.release = tpmrm_release,
 };

Re: [PATCH v4 1/2] tpm: add ptr to the tpm_space struct to file_priv

[Jarkko Sakkinen]

On Tue, Aug 07, 2018 at 01:27:44PM -0700, Tadeusz Struk wrote:
> Add a ptr to struct tpm_space to the file_priv to have an easy
> access to it in the async job without the need to allocate memory.
> This also allows to consolidate of the write operations for
> the two interfaces.

I think the 2nd premise should be the priority and the first premise should
be removed as it is not needed in any possible way to justify the
change.

/Jarkko

Re: [PATCH v4 2/2] tpm: add support for nonblocking operation

[Jarkko Sakkinen]

On Tue, Aug 07, 2018 at 01:27:49PM -0700, Tadeusz Struk wrote:
> Currently the TPM driver only supports blocking calls, which doesn't allow
> asynchronous IO operations to the TPM hardware.
> This patch changes it and adds support for nonblocking write and a new poll
> function to enable applications, which want to take advantage of this.
> 
> Tested-by: Philip Tricca <philip.b.tricca@intel.com>
> Signed-off-by: Tadeusz Struk <tadeusz.struk@intel.com>
> ---
>  drivers/char/tpm/tpm-dev-common.c |  149 ++++++++++++++++++++++++++++---------
>  drivers/char/tpm/tpm-dev.c        |   16 +++-
>  drivers/char/tpm/tpm-dev.h        |   17 +++-
>  drivers/char/tpm/tpm-interface.c  |    1 
>  drivers/char/tpm/tpm.h            |    1 
>  drivers/char/tpm/tpmrm-dev.c      |   19 +++--
>  6 files changed, 150 insertions(+), 53 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm-dev-common.c b/drivers/char/tpm/tpm-dev-common.c
> index f0c033b69b62..f71d80b94451 100644
> --- a/drivers/char/tpm/tpm-dev-common.c
> +++ b/drivers/char/tpm/tpm-dev-common.c
> @@ -17,11 +17,36 @@
>   * License.
>   *
>   */
> +#include <linux/poll.h>
>  #include <linux/slab.h>
>  #include <linux/uaccess.h>
> +#include <linux/workqueue.h>
>  #include "tpm.h"
>  #include "tpm-dev.h"
>  
> +static struct workqueue_struct *tpm_dev_wq;

A naming contradiction with tpm_common_read() and tpm_common_write(). To
sort that up I would suggest adding a commit to the patch set that
renames these functions as tpm_dev_common_read() and
tpm_dev_common_write() and use the name tpm_common_dev_wq here.

> +static DEFINE_MUTEX(tpm_dev_wq_lock);

This is an unacceptable way to do it, Rather add:

int __init  tpm_dev_common_init(void)
{
	tpm_dev_common_wq = alloc_workqueue("tpm_dev_wq", WQ_MEM_RECLAIM, 0);
	if (!tpm_dev_common_wq)
		return -ENOMEM;

	return 0;
}

and call this in the driver initialization.

> +
> +static void tpm_async_work(struct work_struct *work)
> +{
> +	struct file_priv *priv =
> +			container_of(work, struct file_priv, async_work);
> +	ssize_t ret;
> +
> +	mutex_lock(&priv->buffer_mutex);
> +	priv->command_enqueued = false;
> +	ret = tpm_transmit(priv->chip, priv->space, priv->data_buffer,
> +			   sizeof(priv->data_buffer), 0);
> +
> +	tpm_put_ops(priv->chip);
> +	if (ret > 0) {
> +		priv->data_pending = ret;
> +		mod_timer(&priv->user_read_timer, jiffies + (120 * HZ));
> +	}
> +	mutex_unlock(&priv->buffer_mutex);
> +	wake_up_interruptible(&priv->async_wait);
> +}
> +
>  static void user_reader_timeout(struct timer_list *t)
>  {
>  	struct file_priv *priv = from_timer(priv, t, user_read_timer);
> @@ -29,30 +54,44 @@ static void user_reader_timeout(struct timer_list *t)
>  	pr_warn("TPM user space timeout is deprecated (pid=%d)\n",
>  		task_tgid_nr(current));
>  
> -	schedule_work(&priv->work);
> +	schedule_work(&priv->timeout_work);
>  }
>  
> -static void timeout_work(struct work_struct *work)
> +static void tpm_timeout_work(struct work_struct *work)
>  {
> -	struct file_priv *priv = container_of(work, struct file_priv, work);
> +	struct file_priv *priv = container_of(work, struct file_priv,
> +					      timeout_work);
>  
>  	mutex_lock(&priv->buffer_mutex);
>  	priv->data_pending = 0;
>  	memset(priv->data_buffer, 0, sizeof(priv->data_buffer));
>  	mutex_unlock(&priv->buffer_mutex);
> +	wake_up_interruptible(&priv->async_wait);
>  }
>  
> -void tpm_common_open(struct file *file, struct tpm_chip *chip,
> -		     struct file_priv *priv, struct tpm_space *space)
> +int tpm_common_open(struct file *file, struct tpm_chip *chip,
> +		    struct file_priv *priv, struct tpm_space *space)
>  {
>  	priv->chip = chip;
>  	priv->space = space;
>  
>  	mutex_init(&priv->buffer_mutex);
>  	timer_setup(&priv->user_read_timer, user_reader_timeout, 0);
> -	INIT_WORK(&priv->work, timeout_work);
> -
> +	INIT_WORK(&priv->timeout_work, tpm_timeout_work);
> +	INIT_WORK(&priv->async_work, tpm_async_work);
> +	init_waitqueue_head(&priv->async_wait);
>  	file->private_data = priv;
> +	mutex_lock(&tpm_dev_wq_lock);
> +	if (!tpm_dev_wq) {
> +		tpm_dev_wq = alloc_workqueue("tpm_dev_wq", WQ_MEM_RECLAIM, 0);
> +		if (!tpm_dev_wq) {
> +			mutex_unlock(&tpm_dev_wq_lock);
> +			return -ENOMEM;
> +		}
> +	}
> +
> +	mutex_unlock(&tpm_dev_wq_lock);
> +	return 0;
>  }
>  
>  ssize_t tpm_common_read(struct file *file, char __user *buf,
> @@ -63,15 +102,17 @@ ssize_t tpm_common_read(struct file *file, char __user *buf,
>  	int rc;
>  
>  	del_singleshot_timer_sync(&priv->user_read_timer);
> -	flush_work(&priv->work);
> +	flush_work(&priv->timeout_work);
>  	mutex_lock(&priv->buffer_mutex);
>  
>  	if (priv->data_pending) {
>  		ret_size = min_t(ssize_t, size, priv->data_pending);
> -		rc = copy_to_user(buf, priv->data_buffer, ret_size);
> -		memset(priv->data_buffer, 0, priv->data_pending);
> -		if (rc)
> -			ret_size = -EFAULT;
> +		if (ret_size > 0) {
> +			rc = copy_to_user(buf, priv->data_buffer, ret_size);
> +			memset(priv->data_buffer, 0, priv->data_pending);
> +			if (rc)
> +				ret_size = -EFAULT;
> +		}
>  
>  		priv->data_pending = 0;
>  	}
> @@ -84,10 +125,9 @@ ssize_t tpm_common_write(struct file *file, const char __user *buf,
>  			 size_t size, loff_t *off)
>  {
>  	struct file_priv *priv = file->private_data;
> -	size_t in_size = size;

/Jarkko

Re: [PATCH v4 1/2] tpm: add ptr to the tpm_space struct to file_priv

[Tadeusz Struk]

On 08/10/2018 10:27 AM, Jarkko Sakkinen wrote:
> On Tue, Aug 07, 2018 at 01:27:44PM -0700, Tadeusz Struk wrote:
>> Add a ptr to struct tpm_space to the file_priv to have an easy
>> access to it in the async job without the need to allocate memory.
>> This also allows to consolidate of the write operations for
>> the two interfaces.
> 
> I think the 2nd premise should be the priority and the first premise should
> be removed as it is not needed in any possible way to justify the
> change.

Jarkko,
The main reason why the pointer to tpm_space struct was added to the
file_priv was to have access to space in the async job when it is enqueued
via the /dev/tpm<N> interface. Currently it is only available in tpmrm_priv.
Otherwise I would need to introduce yet another struct what would consist of
a ptr file_priv and a ptr to tpm_space and allocate it on every enqueue.
Much easier was to to it this way. The consolidation was only a side effect
of this so I think the description is correct.
Thanks,
-- 
Tadeusz

Re: [PATCH v4 2/2] tpm: add support for nonblocking operation

[Tadeusz Struk]

On 08/10/2018 10:43 AM, Jarkko Sakkinen wrote:
>> +static struct workqueue_struct *tpm_dev_wq;
> A naming contradiction with tpm_common_read() and tpm_common_write(). To
> sort that up I would suggest adding a commit to the patch set that
> renames these functions as tpm_dev_common_read() and
> tpm_dev_common_write() and use the name tpm_common_dev_wq here.
> 

Currently we have: tpm_open(), tpm_write(), tpm_release() in tpm-dev.c
tpmrm_open(), tpmrm_read(), tpmrm_write(), tpmrm_release() in tpmrm-dev.c
tpm_common_open(), tpm_common_read(), tpm_common_write(), tpm_common_release() in tpm-dev-common.c

I think that's pretty consistent. Do you want me to rename all of them to tpm_dev_*()?
I don't see any value in doing this. What about if I just rename: 
tpm_dev_wq_lock to tpm_common_wq_lock, and tpm_dev_wq to tpm_common_wq?

>> +static DEFINE_MUTEX(tpm_dev_wq_lock);
> This is an unacceptable way to do it, Rather add:
> 
> int __init  tpm_dev_common_init(void)
> {
> 	tpm_dev_common_wq = alloc_workqueue("tpm_dev_wq", WQ_MEM_RECLAIM, 0);
> 	if (!tpm_dev_common_wq)
> 		return -ENOMEM;
> 
> 	return 0;
> }
> 
> and call this in the driver initialization.
> 
That was the way it was implemented in v1 https://patchwork.kernel.org/patch/10442125/

See: static int __init tpm_dev_common_init(void)

and the feedback I got from Jason was:

"I wonder if it is worth creating this when the first file is
opened.. Lots of systems have TPMs but few use the userspace.."

so I changed this to allocate the WQ on first open. I think it makes sense,
but I leave it to you to decide.

Tadeusz,
-- 
Tadeusz

Re: [PATCH v4 1/2] tpm: add ptr to the tpm_space struct to file_priv

[Jarkko Sakkinen]

On Fri, Aug 10, 2018 at 11:05:17AM -0700, Tadeusz Struk wrote:
> On 08/10/2018 10:27 AM, Jarkko Sakkinen wrote:
> > On Tue, Aug 07, 2018 at 01:27:44PM -0700, Tadeusz Struk wrote:
> >> Add a ptr to struct tpm_space to the file_priv to have an easy
> >> access to it in the async job without the need to allocate memory.
> >> This also allows to consolidate of the write operations for
> >> the two interfaces.
> > 
> > I think the 2nd premise should be the priority and the first premise should
> > be removed as it is not needed in any possible way to justify the
> > change.
> 
> Jarkko,
> The main reason why the pointer to tpm_space struct was added to the
> file_priv was to have access to space in the async job when it is enqueued
> via the /dev/tpm<N> interface. Currently it is only available in tpmrm_priv.
> Otherwise I would need to introduce yet another struct what would consist of
> a ptr file_priv and a ptr to tpm_space and allocate it on every enqueue.
> Much easier was to to it this way. The consolidation was only a side effect
> of this so I think the description is correct.
> Thanks,
> -- 
> Tadeusz

The less dependencies a commit has more easy it is for me pick up. Here
the consodilation is enough to accept the commit but with the current
commit message I cannot apply it without accepting the whole patch set.

/Jarkko

Re: [PATCH v4 2/2] tpm: add support for nonblocking operation

[James Bottomley]

On Fri, 2018-08-10 at 11:21 -0700, Tadeusz Struk wrote:
> and the feedback I got from Jason was:
> 
> "I wonder if it is worth creating this when the first file is
> opened.. Lots of systems have TPMs but few use the userspace.."
> 
> so I changed this to allocate the WQ on first open. I think it makes
> sense, but I leave it to you to decide.

If the reason is to not create a wq unless it's needed, shouldn't the
condition actually be first open with flag O_NONBLOCK?

James

Re: [PATCH v4 2/2] tpm: add support for nonblocking operation

[Tadeusz Struk]

On 08/10/2018 11:48 AM, James Bottomley wrote:
> On Fri, 2018-08-10 at 11:21 -0700, Tadeusz Struk wrote:
>> and the feedback I got from Jason was:
>>
>> "I wonder if it is worth creating this when the first file is
>> opened.. Lots of systems have TPMs but few use the userspace.."
>>
>> so I changed this to allocate the WQ on first open. I think it makes
>> sense, but I leave it to you to decide.
> 
> If the reason is to not create a wq unless it's needed, shouldn't the
> condition actually be first open with flag O_NONBLOCK?
> 

Not really because one can do:

int fd = open("/dev/tpm0", O_RDWR);
fcntl(fd, F_SETFL, O_NONBLOCK);

-- 
Tadeusz

Re: [PATCH v4 2/2] tpm: add support for nonblocking operation

[James Bottomley]

On Fri, 2018-08-10 at 11:56 -0700, Tadeusz Struk wrote:
> On 08/10/2018 11:48 AM, James Bottomley wrote:
> > On Fri, 2018-08-10 at 11:21 -0700, Tadeusz Struk wrote:
> > > and the feedback I got from Jason was:
> > > 
> > > "I wonder if it is worth creating this when the first file is
> > > opened.. Lots of systems have TPMs but few use the userspace.."
> > > 
> > > so I changed this to allocate the WQ on first open. I think it
> > > makes sense, but I leave it to you to decide.
> > 
> > If the reason is to not create a wq unless it's needed, shouldn't
> > the condition actually be first open with flag O_NONBLOCK?
> > 
> 
> Not really because one can do:
> 
> int fd = open("/dev/tpm0", O_RDWR);
> fcntl(fd, F_SETFL, O_NONBLOCK);

so move the condition to first need to queue ...

James

Re: [PATCH v4 2/2] tpm: add support for nonblocking operation

[Tadeusz Struk]

On 08/10/2018 12:00 PM, James Bottomley wrote:
> On Fri, 2018-08-10 at 11:56 -0700, Tadeusz Struk wrote:
>> On 08/10/2018 11:48 AM, James Bottomley wrote:
>>> On Fri, 2018-08-10 at 11:21 -0700, Tadeusz Struk wrote:
>>>> and the feedback I got from Jason was:
>>>>
>>>> "I wonder if it is worth creating this when the first file is
>>>> opened.. Lots of systems have TPMs but few use the userspace.."
>>>>
>>>> so I changed this to allocate the WQ on first open. I think it
>>>> makes sense, but I leave it to you to decide.
>>>
>>> If the reason is to not create a wq unless it's needed, shouldn't
>>> the condition actually be first open with flag O_NONBLOCK?
>>>
>>
>> Not really because one can do:
>>
>> int fd = open("/dev/tpm0", O_RDWR);
>> fcntl(fd, F_SETFL, O_NONBLOCK);
> 
> so move the condition to first need to queue ...
> 

That would work, even though this is not how this is usually done.
The first open looks like the sweet spot between module init
and first need to queue.
Thanks,
-- 
Tadeusz

Re: [PATCH v4 2/2] tpm: add support for nonblocking operation

[Jarkko Sakkinen]

On Fri, Aug 10, 2018 at 11:21:14AM -0700, Tadeusz Struk wrote:
> On 08/10/2018 10:43 AM, Jarkko Sakkinen wrote:
> >> +static struct workqueue_struct *tpm_dev_wq;
> > A naming contradiction with tpm_common_read() and tpm_common_write(). To
> > sort that up I would suggest adding a commit to the patch set that
> > renames these functions as tpm_dev_common_read() and
> > tpm_dev_common_write() and use the name tpm_common_dev_wq here.
> > 
> 
> Currently we have: tpm_open(), tpm_write(), tpm_release() in tpm-dev.c
> tpmrm_open(), tpmrm_read(), tpmrm_write(), tpmrm_release() in tpmrm-dev.c
> tpm_common_open(), tpm_common_read(), tpm_common_write(), tpm_common_release() in tpm-dev-common.c
> 
> I think that's pretty consistent. Do you want me to rename all of them to tpm_dev_*()?
> I don't see any value in doing this. What about if I just rename: 
> tpm_dev_wq_lock to tpm_common_wq_lock, and tpm_dev_wq to tpm_common_wq?

That is good enough. At least it is consistent.

> >> +static DEFINE_MUTEX(tpm_dev_wq_lock);
> > This is an unacceptable way to do it, Rather add:
> > 
> > int __init  tpm_dev_common_init(void)
> > {
> > 	tpm_dev_common_wq = alloc_workqueue("tpm_dev_wq", WQ_MEM_RECLAIM, 0);
> > 	if (!tpm_dev_common_wq)
> > 		return -ENOMEM;
> > 
> > 	return 0;
> > }
> > 
> > and call this in the driver initialization.
> > 
> That was the way it was implemented in v1 https://patchwork.kernel.org/patch/10442125/
> 
> See: static int __init tpm_dev_common_init(void)
> 
> and the feedback I got from Jason was:
> 
> "I wonder if it is worth creating this when the first file is
> opened.. Lots of systems have TPMs but few use the userspace.."
> 
> so I changed this to allocate the WQ on first open. I think it makes sense,
> but I leave it to you to decide.

Without a question I would go with tpm_common_init() for stability (one
less point of failure in open) and simplicity (no need for a locking
scheme).

> Tadeusz,
> -- 
> Tadeusz

/Jarkko