tpm: Fix the timeout & use ktime

The current implementation of timeout detection works in the following way:

The current implementation of timeout detection works in the following way:

1. Read completion status. If completed, return the data
2. Sleep for some time (usleep_range)
3. Check for timeout using current jiffies value. Return an error if timed out
4. Goto 1

usleep_range doesn't guarantee it's always going to wake up strictly in (min, max) range, so such a situation is possible:

1. Driver reads completion status. No completion yet
2. Process sleeps indefinitely. In the meantime, TPM responds
3. We check for timeout without checking for the completion again. Result is lost.

Such a situation also happens for the guest VMs: if vCPU goes to sleep and doesn't get scheduled for some time, the guest TPM driver will timeout instantly after waking up without checking for the completion (which may already be in place).

Perform the completion check once again after exiting the busy loop in order to give the device the last chance to send us some data.

Since now we check for completion in two places, extract this check into a separate function.

Signed-off-by Ivan Orlov <[email protected]>

---
V1 -> V2:
- Exclude the jiffies -> ktime change from the patch
- Instead of recording the time before checking for completion, check for completion once again after leaving the loop

drivers/char/tpm/tpm-interface.c | 17 +++++++++++++++--

1 file changed, 15 insertions(+), 2 deletions(-)

drivers/char/tpm/tpm-interface.c +7 -0

index 8d7e4da6ed53..6960ee2798e1 100644
@@ -82,6 +82,13 @@ static bool tpm_chip_req_canceled(struct tpm_chip *chip, u8 status)
 	return chip->ops->req_canceled(chip, status);
 }
 
+static bool tpm_transmit_completed(struct tpm_chip *chip)
+{
+	u8 status_masked = tpm_chip_status(chip) & chip->ops->req_complete_mask;
+
+	return status_masked == chip->ops->req_complete_val;
+}
+
 static ssize_t tpm_try_transmit(struct tpm_chip *chip, void *buf, size_t bufsiz)
 {
 	struct tpm_header *header = buf;

drivers/char/tpm/tpm-interface.c +0 -0

 		if (tpm_chip_req_canceled(chip, status)) {

@@ -142,6 +148,13 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip, void *buf, size_t bufsiz)
 		rmb();
 	} while (time_before(jiffies, stop));
 

Quoted 60 lines · Ivan

The current implementation of timeout detection works in the following way:

1. Read completion status. If completed, return the data
2. Sleep for some time (usleep_range)
3. Check for timeout using current jiffies value. Return an error if timed out
4. Goto 1

usleep_range doesn't guarantee it's always going to wake up strictly in (min, max) range, so such a situation is possible:

1. Driver reads completion status. No completion yet
2. Process sleeps indefinitely. In the meantime, TPM responds
3. We check for timeout without checking for the completion again. Result is lost.

Such a situation also happens for the guest VMs: if vCPU goes to sleep and doesn't get scheduled for some time, the guest TPM driver will timeout instantly after waking up without checking for the completion (which may already be in place).

Perform the completion check once again after exiting the busy loop in order to give the device the last chance to send us some data.

Since now we check for completion in two places, extract this check into a separate function.

Signed-off-by Ivan Orlov <[email protected]>

---
V1 -> V2:
- Exclude the jiffies -> ktime change from the patch
- Instead of recording the time before checking for completion, check for completion once again after leaving the loop

drivers/char/tpm/tpm-interface.c | 17 +++++++++++++++--

1 file changed, 15 insertions(+), 2 deletions(-)

drivers/char/tpm/tpm-interface.c +7 -0

index 8d7e4da6ed53..6960ee2798e1 100644
@@ -82,6 +82,13 @@ static bool tpm_chip_req_canceled(struct tpm_chip *chip, u8 status)
 	return chip->ops->req_canceled(chip, status);
 }
 
+static bool tpm_transmit_completed(struct tpm_chip *chip)
+{
+	u8 status_masked = tpm_chip_status(chip) & chip->ops->req_complete_mask;
+
+	return status_masked == chip->ops->req_complete_val;
+}
+
 static ssize_t tpm_try_transmit(struct tpm_chip *chip, void *buf, size_t bufsiz)
 {
 	struct tpm_header *header = buf;

@@ -129,8 +136,7 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip, void *buf, size_t bufsiz)
 	stop = jiffies + tpm_calc_ordinal_duration(chip, ordinal);
 	do {
 		u8 status = tpm_chip_status(chip);

drivers/char/tpm/tpm-interface.c static ssize_t tpm_try_transmit(struct tpm_chip *chip, void *buf, size_t bufsiz) · line 140

Quoted 4 lines

drivers/char/tpm/tpm-interface.c +1 -2

-		if ((status & chip->ops->req_complete_mask) ==
-		    chip->ops->req_complete_val)
+		if (tpm_transmit_completed(chip))
 			goto out_recv;

The only thing I'd point out here is we end up doing a double status read one after the other (once here, once in tpm_transmit_completed), and I'm pretty sure I've seen instances where that caused a problem.

Quoted 61 lines · Jonathan McDowell

Quoted 60 lines · Ivan

The current implementation of timeout detection works in the following way:

1. Read completion status. If completed, return the data
2. Sleep for some time (usleep_range)
3. Check for timeout using current jiffies value. Return an error if timed out
4. Goto 1

usleep_range doesn't guarantee it's always going to wake up strictly in (min, max) range, so such a situation is possible:

1. Driver reads completion status. No completion yet
2. Process sleeps indefinitely. In the meantime, TPM responds
3. We check for timeout without checking for the completion again. Result is lost.

Such a situation also happens for the guest VMs: if vCPU goes to sleep and doesn't get scheduled for some time, the guest TPM driver will timeout instantly after waking up without checking for the completion (which may already be in place).

Perform the completion check once again after exiting the busy loop in order to give the device the last chance to send us some data.

Since now we check for completion in two places, extract this check into a separate function.

Signed-off-by Ivan Orlov <[email protected]>

---
V1 -> V2:
- Exclude the jiffies -> ktime change from the patch
- Instead of recording the time before checking for completion, check for completion once again after leaving the loop

drivers/char/tpm/tpm-interface.c | 17 +++++++++++++++--

1 file changed, 15 insertions(+), 2 deletions(-)

drivers/char/tpm/tpm-interface.c +7 -0

index 8d7e4da6ed53..6960ee2798e1 100644
@@ -82,6 +82,13 @@ static bool tpm_chip_req_canceled(struct tpm_chip *chip, u8 status)
 	return chip->ops->req_canceled(chip, status);
 }
 
+static bool tpm_transmit_completed(struct tpm_chip *chip)
+{
+	u8 status_masked = tpm_chip_status(chip) & chip->ops->req_complete_mask;
+
+	return status_masked == chip->ops->req_complete_val;
+}
+
 static ssize_t tpm_try_transmit(struct tpm_chip *chip, void *buf, size_t bufsiz)
 {
 	struct tpm_header *header = buf;

@@ -129,8 +136,7 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip, void *buf, size_t bufsiz)
 	stop = jiffies + tpm_calc_ordinal_duration(chip, ordinal);
 	do {
 		u8 status = tpm_chip_status(chip);

Quoted 8 lines

drivers/char/tpm/tpm-interface.c static ssize_t tpm_try_transmit(struct tpm_chip *chip, void *buf, size_t bufsiz) · line 140

Quoted 4 lines

drivers/char/tpm/tpm-interface.c +1 -2

-		if ((status & chip->ops->req_complete_mask) ==
-		    chip->ops->req_complete_val)
+		if (tpm_transmit_completed(chip))
 			goto out_recv;

The only thing I'd point out here is we end up doing a double status read one after the other (once here, once in tpm_transmit_completed), and I'm pretty sure I've seen instances where that caused a problem.

It would be easy to to prevent at least double reads after completion e.g., in tpm_chip_status():

/*
* Read the chip status bitmask. After completion, the returned will mask will
* return value cached at the point of completion up until the next transmit. */
static u8 tpm_chip_status(struct tpm_chip *chip)

{
	u8 status_masked = chip->status & chip->ops_req_complete_mask;

	if (status_masked == chip->ops->req_complete_val)
		return chip->status;

	chip->status = tpm_chip_status(chip);

Quoted 61 lines · Jonathan McDowell

Quoted 60 lines · Ivan

The current implementation of timeout detection works in the following way:

1. Read completion status. If completed, return the data
2. Sleep for some time (usleep_range)
3. Check for timeout using current jiffies value. Return an error if timed out
4. Goto 1

usleep_range doesn't guarantee it's always going to wake up strictly in (min, max) range, so such a situation is possible:

1. Driver reads completion status. No completion yet
2. Process sleeps indefinitely. In the meantime, TPM responds
3. We check for timeout without checking for the completion again. Result is lost.

Such a situation also happens for the guest VMs: if vCPU goes to sleep and doesn't get scheduled for some time, the guest TPM driver will timeout instantly after waking up without checking for the completion (which may already be in place).

Perform the completion check once again after exiting the busy loop in order to give the device the last chance to send us some data.

Since now we check for completion in two places, extract this check into a separate function.

Signed-off-by Ivan Orlov <[email protected]>

---
V1 -> V2:
- Exclude the jiffies -> ktime change from the patch
- Instead of recording the time before checking for completion, check for completion once again after leaving the loop

drivers/char/tpm/tpm-interface.c | 17 +++++++++++++++--

1 file changed, 15 insertions(+), 2 deletions(-)

drivers/char/tpm/tpm-interface.c +7 -0

index 8d7e4da6ed53..6960ee2798e1 100644
@@ -82,6 +82,13 @@ static bool tpm_chip_req_canceled(struct tpm_chip *chip, u8 status)
 	return chip->ops->req_canceled(chip, status);
 }
 
+static bool tpm_transmit_completed(struct tpm_chip *chip)
+{
+	u8 status_masked = tpm_chip_status(chip) & chip->ops->req_complete_mask;
+
+	return status_masked == chip->ops->req_complete_val;
+}
+
 static ssize_t tpm_try_transmit(struct tpm_chip *chip, void *buf, size_t bufsiz)
 {
 	struct tpm_header *header = buf;

@@ -129,8 +136,7 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip, void *buf, size_t bufsiz)
 	stop = jiffies + tpm_calc_ordinal_duration(chip, ordinal);
 	do {
 		u8 status = tpm_chip_status(chip);

Quoted 8 lines

drivers/char/tpm/tpm-interface.c static ssize_t tpm_try_transmit(struct tpm_chip *chip, void *buf, size_t bufsiz) · line 140

Quoted 4 lines

drivers/char/tpm/tpm-interface.c +1 -2

-		if ((status & chip->ops->req_complete_mask) ==
-		    chip->ops->req_complete_val)
+		if (tpm_transmit_completed(chip))
 			goto out_recv;

The only thing I'd point out here is we end up doing a double status read one after the other (once here, once in tpm_transmit_completed), and I'm pretty sure I've seen instances where that caused a problem.

It would be easy to to prevent at least double reads after completion e.g., in tpm_chip_status():

Quoted 71 lines · Jarkko Sakkinen

Quoted 61 lines · Jonathan McDowell

Quoted 60 lines · Ivan

The current implementation of timeout detection works in the following way:

1. Read completion status. If completed, return the data
2. Sleep for some time (usleep_range)
3. Check for timeout using current jiffies value. Return an error if timed out
4. Goto 1

usleep_range doesn't guarantee it's always going to wake up strictly in (min, max) range, so such a situation is possible:

1. Driver reads completion status. No completion yet
2. Process sleeps indefinitely. In the meantime, TPM responds
3. We check for timeout without checking for the completion again. Result is lost.

Such a situation also happens for the guest VMs: if vCPU goes to sleep and doesn't get scheduled for some time, the guest TPM driver will timeout instantly after waking up without checking for the completion (which may already be in place).

Perform the completion check once again after exiting the busy loop in order to give the device the last chance to send us some data.

Since now we check for completion in two places, extract this check into a separate function.

Signed-off-by Ivan Orlov <[email protected]>

---
V1 -> V2:
- Exclude the jiffies -> ktime change from the patch
- Instead of recording the time before checking for completion, check for completion once again after leaving the loop

drivers/char/tpm/tpm-interface.c | 17 +++++++++++++++--

1 file changed, 15 insertions(+), 2 deletions(-)

drivers/char/tpm/tpm-interface.c +7 -0

index 8d7e4da6ed53..6960ee2798e1 100644
@@ -82,6 +82,13 @@ static bool tpm_chip_req_canceled(struct tpm_chip *chip, u8 status)
 	return chip->ops->req_canceled(chip, status);
 }
 
+static bool tpm_transmit_completed(struct tpm_chip *chip)
+{
+	u8 status_masked = tpm_chip_status(chip) & chip->ops->req_complete_mask;
+
+	return status_masked == chip->ops->req_complete_val;
+}
+
 static ssize_t tpm_try_transmit(struct tpm_chip *chip, void *buf, size_t bufsiz)
 {
 	struct tpm_header *header = buf;

@@ -129,8 +136,7 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip, void *buf, size_t bufsiz)
 	stop = jiffies + tpm_calc_ordinal_duration(chip, ordinal);
 	do {
 		u8 status = tpm_chip_status(chip);

Quoted 8 lines

drivers/char/tpm/tpm-interface.c static ssize_t tpm_try_transmit(struct tpm_chip *chip, void *buf, size_t bufsiz) · line 140

Quoted 4 lines

drivers/char/tpm/tpm-interface.c +1 -2

-		if ((status & chip->ops->req_complete_mask) ==
-		    chip->ops->req_complete_val)
+		if (tpm_transmit_completed(chip))
 			goto out_recv;

The only thing I'd point out here is we end up doing a double status read one after the other (once here, once in tpm_transmit_completed), and I'm pretty sure I've seen instances where that caused a problem.

Quoted 2 lines

It would be easy to to prevent at least double reads after completion e.g., in tpm_chip_status():

Or just take the simple approach and make the check after the while loop:

	if ((tpm_chip_status(chip) & chip->ops->req_complete_mask) ==
	    chip->ops->req_complete_val)
		goto out_recv;

There might be potential for a longer term cleanup using chip->status to cache things, but I'm little concerned that's going to open paths where we might not correctly update it, so I think it should be a separate piece.

(I'm motivated by the fact we've started to see the "Operation Canceled" error and I'd like us to close on the best way to fix it. :) )

J.

Signature · 1 line

I am afraid of the dark.

Quoted 81 lines · Jonathan McDowell

Quoted 71 lines · Jarkko Sakkinen

Quoted 61 lines · Jonathan McDowell

Quoted 60 lines · Ivan

The current implementation of timeout detection works in the following way:

1. Read completion status. If completed, return the data
2. Sleep for some time (usleep_range)
3. Check for timeout using current jiffies value. Return an error if timed out
4. Goto 1

usleep_range doesn't guarantee it's always going to wake up strictly in (min, max) range, so such a situation is possible:

1. Driver reads completion status. No completion yet
2. Process sleeps indefinitely. In the meantime, TPM responds
3. We check for timeout without checking for the completion again. Result is lost.

Such a situation also happens for the guest VMs: if vCPU goes to sleep and doesn't get scheduled for some time, the guest TPM driver will timeout instantly after waking up without checking for the completion (which may already be in place).

Perform the completion check once again after exiting the busy loop in order to give the device the last chance to send us some data.

Since now we check for completion in two places, extract this check into a separate function.

Signed-off-by Ivan Orlov <[email protected]>

---
V1 -> V2:
- Exclude the jiffies -> ktime change from the patch
- Instead of recording the time before checking for completion, check for completion once again after leaving the loop

drivers/char/tpm/tpm-interface.c | 17 +++++++++++++++--

1 file changed, 15 insertions(+), 2 deletions(-)

drivers/char/tpm/tpm-interface.c +7 -0

index 8d7e4da6ed53..6960ee2798e1 100644
@@ -82,6 +82,13 @@ static bool tpm_chip_req_canceled(struct tpm_chip *chip, u8 status)
 	return chip->ops->req_canceled(chip, status);
 }
 
+static bool tpm_transmit_completed(struct tpm_chip *chip)
+{
+	u8 status_masked = tpm_chip_status(chip) & chip->ops->req_complete_mask;
+
+	return status_masked == chip->ops->req_complete_val;
+}
+
 static ssize_t tpm_try_transmit(struct tpm_chip *chip, void *buf, size_t bufsiz)
 {
 	struct tpm_header *header = buf;

@@ -129,8 +136,7 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip, void *buf, size_t bufsiz)
 	stop = jiffies + tpm_calc_ordinal_duration(chip, ordinal);
 	do {
 		u8 status = tpm_chip_status(chip);

Quoted 8 lines

drivers/char/tpm/tpm-interface.c static ssize_t tpm_try_transmit(struct tpm_chip *chip, void *buf, size_t bufsiz) · line 140

Quoted 4 lines

drivers/char/tpm/tpm-interface.c +1 -2

-		if ((status & chip->ops->req_complete_mask) ==
-		    chip->ops->req_complete_val)
+		if (tpm_transmit_completed(chip))
 			goto out_recv;

The only thing I'd point out here is we end up doing a double status read one after the other (once here, once in tpm_transmit_completed), and I'm pretty sure I've seen instances where that caused a problem.

Quoted 2 lines

It would be easy to to prevent at least double reads after completion e.g., in tpm_chip_status():

Or just take the simple approach and make the check after the while loop:

	if ((tpm_chip_status(chip) & chip->ops->req_complete_mask) ==
	    chip->ops->req_complete_val)
		goto out_recv;

Quoted 6 lines

There might be potential for a longer term cleanup using chip->status to cache things, but I'm little concerned that's going to open paths where we might not correctly update it, so I think it should be a separate piece.

(I'm motivated by the fact we've started to see the "Operation Canceled" error and I'd like us to close on the best way to fix it. :) )

This would work for me too!

Quoted 89 lines · Jarkko Sakkinen

Quoted 87 lines · Jonathan McDowell

Quoted 71 lines · Jarkko Sakkinen

Quoted 61 lines · Jonathan McDowell

Quoted 60 lines · Ivan

The current implementation of timeout detection works in the following way:

1. Read completion status. If completed, return the data
2. Sleep for some time (usleep_range)
3. Check for timeout using current jiffies value. Return an error if timed out
4. Goto 1

usleep_range doesn't guarantee it's always going to wake up strictly in (min, max) range, so such a situation is possible:

1. Driver reads completion status. No completion yet
2. Process sleeps indefinitely. In the meantime, TPM responds
3. We check for timeout without checking for the completion again. Result is lost.

Such a situation also happens for the guest VMs: if vCPU goes to sleep and doesn't get scheduled for some time, the guest TPM driver will timeout instantly after waking up without checking for the completion (which may already be in place).

Perform the completion check once again after exiting the busy loop in order to give the device the last chance to send us some data.

Since now we check for completion in two places, extract this check into a separate function.

Signed-off-by Ivan Orlov <[email protected]>

---
V1 -> V2:
- Exclude the jiffies -> ktime change from the patch
- Instead of recording the time before checking for completion, check for completion once again after leaving the loop

drivers/char/tpm/tpm-interface.c | 17 +++++++++++++++--

1 file changed, 15 insertions(+), 2 deletions(-)

drivers/char/tpm/tpm-interface.c +7 -0

index 8d7e4da6ed53..6960ee2798e1 100644
@@ -82,6 +82,13 @@ static bool tpm_chip_req_canceled(struct tpm_chip *chip, u8 status)
 	return chip->ops->req_canceled(chip, status);
 }
 
+static bool tpm_transmit_completed(struct tpm_chip *chip)
+{
+	u8 status_masked = tpm_chip_status(chip) & chip->ops->req_complete_mask;
+
+	return status_masked == chip->ops->req_complete_val;
+}
+
 static ssize_t tpm_try_transmit(struct tpm_chip *chip, void *buf, size_t bufsiz)
 {
 	struct tpm_header *header = buf;

@@ -129,8 +136,7 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip, void *buf, size_t bufsiz)
 	stop = jiffies + tpm_calc_ordinal_duration(chip, ordinal);
 	do {
 		u8 status = tpm_chip_status(chip);

Quoted 8 lines

drivers/char/tpm/tpm-interface.c static ssize_t tpm_try_transmit(struct tpm_chip *chip, void *buf, size_t bufsiz) · line 140

Quoted 4 lines

drivers/char/tpm/tpm-interface.c +1 -2

-		if ((status & chip->ops->req_complete_mask) ==
-		    chip->ops->req_complete_val)
+		if (tpm_transmit_completed(chip))
 			goto out_recv;

The only thing I'd point out here is we end up doing a double status read one after the other (once here, once in tpm_transmit_completed), and I'm pretty sure I've seen instances where that caused a problem.

Quoted 2 lines

It would be easy to to prevent at least double reads after completion e.g., in tpm_chip_status():

Or just take the simple approach and make the check after the while loop:

	if ((tpm_chip_status(chip) & chip->ops->req_complete_mask) ==
	    chip->ops->req_complete_val)
		goto out_recv;

There might be potential for a longer term cleanup using chip->status to cache things, but I'm little concerned that's going to open paths where we might not correctly update it, so I think it should be a separate piece.

(I'm motivated by the fact we've started to see the "Operation Canceled" error and I'd like us to close on the best way to fix it. :) )

Quoted 2 lines

This would work for me too!

Hi, and sorry for the late reply :(

I believe this option would work for us as well. Please let me know whether you'd like me to send V3 or you feel free to send it yourself if you want.

Quoted 89 lines · Jarkko Sakkinen

Quoted 87 lines · Jonathan McDowell

Quoted 71 lines · Jarkko Sakkinen

Quoted 61 lines · Jonathan McDowell

Quoted 60 lines · Ivan

The current implementation of timeout detection works in the following way:

1. Read completion status. If completed, return the data
2. Sleep for some time (usleep_range)
3. Check for timeout using current jiffies value. Return an error if timed out
4. Goto 1

usleep_range doesn't guarantee it's always going to wake up strictly in (min, max) range, so such a situation is possible:

1. Driver reads completion status. No completion yet
2. Process sleeps indefinitely. In the meantime, TPM responds
3. We check for timeout without checking for the completion again. Result is lost.

Such a situation also happens for the guest VMs: if vCPU goes to sleep and doesn't get scheduled for some time, the guest TPM driver will timeout instantly after waking up without checking for the completion (which may already be in place).

Perform the completion check once again after exiting the busy loop in order to give the device the last chance to send us some data.

Since now we check for completion in two places, extract this check into a separate function.

Signed-off-by Ivan Orlov <[email protected]>

---
V1 -> V2:
- Exclude the jiffies -> ktime change from the patch
- Instead of recording the time before checking for completion, check for completion once again after leaving the loop

drivers/char/tpm/tpm-interface.c | 17 +++++++++++++++--

1 file changed, 15 insertions(+), 2 deletions(-)

drivers/char/tpm/tpm-interface.c +7 -0

index 8d7e4da6ed53..6960ee2798e1 100644
@@ -82,6 +82,13 @@ static bool tpm_chip_req_canceled(struct tpm_chip *chip, u8 status)
 	return chip->ops->req_canceled(chip, status);
 }
 
+static bool tpm_transmit_completed(struct tpm_chip *chip)
+{
+	u8 status_masked = tpm_chip_status(chip) & chip->ops->req_complete_mask;
+
+	return status_masked == chip->ops->req_complete_val;
+}
+
 static ssize_t tpm_try_transmit(struct tpm_chip *chip, void *buf, size_t bufsiz)
 {
 	struct tpm_header *header = buf;

@@ -129,8 +136,7 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip, void *buf, size_t bufsiz)
 	stop = jiffies + tpm_calc_ordinal_duration(chip, ordinal);
 	do {
 		u8 status = tpm_chip_status(chip);

Quoted 8 lines

drivers/char/tpm/tpm-interface.c static ssize_t tpm_try_transmit(struct tpm_chip *chip, void *buf, size_t bufsiz) · line 140

Quoted 4 lines

drivers/char/tpm/tpm-interface.c +1 -2

-		if ((status & chip->ops->req_complete_mask) ==
-		    chip->ops->req_complete_val)
+		if (tpm_transmit_completed(chip))
 			goto out_recv;

The only thing I'd point out here is we end up doing a double status read one after the other (once here, once in tpm_transmit_completed), and I'm pretty sure I've seen instances where that caused a problem.

Quoted 2 lines

It would be easy to to prevent at least double reads after completion e.g., in tpm_chip_status():

Or just take the simple approach and make the check after the while loop:

	if ((tpm_chip_status(chip) & chip->ops->req_complete_mask) ==
	    chip->ops->req_complete_val)
		goto out_recv;

There might be potential for a longer term cleanup using chip->status to cache things, but I'm little concerned that's going to open paths where we might not correctly update it, so I think it should be a separate piece.

(I'm motivated by the fact we've started to see the "Operation Canceled" error and I'd like us to close on the best way to fix it. :) )

Quoted 2 lines

This would work for me too!

Hi, and sorry for the late reply :(

I believe this option would work for us as well. Please let me know whether you'd like me to send V3 or you feel free to send it yourself if you want.

--
Kind regards,
Ivan Orlov

Quoted 2 lines

I believe this option would work for us as well. Please let me know whether you'd like me to send V3 or you feel free to send it yourself if you want.

Please send one more patch. I just came from holiday and now have hands full backtracking last two weeks.