[PATCH] selftests/powerpc: Do not fail on TM_CAUSE_RESCHED

[PATCH] selftests/powerpc: Do not fail on TM_CAUSE_RESCHED

[Breno Leitao]

There are cases where the test is not expecting to have the transaction
aborted, but, the test process might have been rescheduled, either in the OS
level or by KVM (if it is running on a KVM guest machine). The process
reschedule will cause a treclaim/recheckpoint which will cause the transaction
to doom, failing as soon as the process is rescheduled back to the CPU. This
might cause the test to fail, but this is not a failure in essence.

If that is the case, TEXASR[FC] is indicated with either
TM_CAUSE_RESCHEDULE or TM_CAUSE_KVM_RESCHEDULE for KVM interruptions.

In this scenario, ignore these two failures and avoid the whole test to return
failure.

CC: Gustavo Romero <gromero@linux.vnet.ibm.com>
Signed-off-by: Breno Leitao <leitao@debian.org>
---
 tools/testing/selftests/powerpc/tm/tm-unavailable.c | 10 +++++++---
 tools/testing/selftests/powerpc/tm/tm.h             |  9 +++++++++
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/powerpc/tm/tm-unavailable.c b/tools/testing/selftests/powerpc/tm/tm-unavailable.c
index 156c8e750259..0fd793f574c3 100644
--- a/tools/testing/selftests/powerpc/tm/tm-unavailable.c
+++ b/tools/testing/selftests/powerpc/tm/tm-unavailable.c
@@ -236,7 +236,8 @@ void *tm_una_ping(void *input)
 	}
 
 	/* Check if we were not expecting a failure and a it occurred. */
-	if (!expecting_failure() && is_failure(cr_)) {
+	if (!expecting_failure() && is_failure(cr_) &&
+	    !failure_is_reschedule()) {
 		printf("\n\tUnexpected transaction failure 0x%02lx\n\t",
 			failure_code());
 		return (void *) -1;
@@ -244,9 +245,12 @@ void *tm_una_ping(void *input)
 
 	/*
 	 * Check if TM failed due to the cause we were expecting. 0xda is a
-	 * TM_CAUSE_FAC_UNAV cause, otherwise it's an unexpected cause.
+	 * TM_CAUSE_FAC_UNAV cause, otherwise it's an unexpected cause, unless
+	 * it was caused by a reschedule.
 	 */
-	if (is_failure(cr_) && !failure_is_unavailable()) {
+
+	if (is_failure(cr_) && !failure_is_unavailable()
+	    & !failure_is_reschedule()) {
 		printf("\n\tUnexpected failure cause 0x%02lx\n\t",
 			failure_code());
 		return (void *) -1;
diff --git a/tools/testing/selftests/powerpc/tm/tm.h b/tools/testing/selftests/powerpc/tm/tm.h
index df4204247d45..5518b1d4ef8b 100644
--- a/tools/testing/selftests/powerpc/tm/tm.h
+++ b/tools/testing/selftests/powerpc/tm/tm.h
@@ -52,6 +52,15 @@ static inline bool failure_is_unavailable(void)
 	return (failure_code() & TM_CAUSE_FAC_UNAV) == TM_CAUSE_FAC_UNAV;
 }
 
+static inline bool failure_is_reschedule(void)
+{
+	if ((failure_code() & TM_CAUSE_RESCHED) == TM_CAUSE_RESCHED ||
+	    (failure_code() & TM_CAUSE_KVM_RESCHED) == TM_CAUSE_KVM_RESCHED)
+		return true;
+
+	return false;
+}
+
 static inline bool failure_is_nesting(void)
 {
 	return (__builtin_get_texasru() & 0x400000);
-- 
2.16.3

Re: [PATCH] selftests/powerpc: Do not fail on TM_CAUSE_RESCHED

[Gustavo Romero]

Hi Breno,

On 08/21/2018 03:56 PM, Breno Leitao wrote:
> There are cases where the test is not expecting to have the transaction
> aborted, but, the test process might have been rescheduled, either in the OS
> level or by KVM (if it is running on a KVM guest machine). The process
> reschedule will cause a treclaim/recheckpoint which will cause the transaction
> to doom, failing as soon as the process is rescheduled back to the CPU. This
> might cause the test to fail, but this is not a failure in essence.
> 
> If that is the case, TEXASR[FC] is indicated with either
> TM_CAUSE_RESCHEDULE or TM_CAUSE_KVM_RESCHEDULE for KVM interruptions.
> 
> In this scenario, ignore these two failures and avoid the whole test to return
> failure.
> 
> Signed-off-by: Breno Leitao <leitao@debian.org>

Thanks for improving the code.

I understand that filtering out the aborts caused by the re-schedules is correct.

Only a nit:

> @@ -244,9 +245,12 @@ void *tm_una_ping(void *input)
> 
>   	/*
>   	 * Check if TM failed due to the cause we were expecting. 0xda is a
> -	 * TM_CAUSE_FAC_UNAV cause, otherwise it's an unexpected cause.
> +	 * TM_CAUSE_FAC_UNAV cause, otherwise it's an unexpected cause, unless
> +	 * it was caused by a reschedule.
>   	 */
> -	if (is_failure(cr_) && !failure_is_unavailable()) {
> +
> +	if (is_failure(cr_) && !failure_is_unavailable()
> +	    & !failure_is_reschedule()) {

             ^---

It should read a short-circuit operator here instead of a bitwise operator.

Otherwise it LGTM.

Reviewed-by: Gustavo Romero <gromero@linux.ibm.com>


Best regards,
Gustavo

[PATCH v2] selftests/powerpc: Do not fail with reschedule

[Breno Leitao]

There are cases where the test is not expecting to have the transaction
aborted, but, the test process might have been rescheduled, either in the
OS level or by KVM (if it is running on a KVM guest machine). The process
reschedule will cause a treclaim/recheckpoint which will cause the
transaction to doom, aborting the transaction as soon as the process is
rescheduled back to the CPU. This might cause the test to fail, but this is
not a failure in essence.

If that is the case, TEXASR[FC] is indicated with either
TM_CAUSE_RESCHEDULE or TM_CAUSE_KVM_RESCHEDULE for KVM interruptions.

In this scenario, ignore these two failures and avoid the whole test to
return failure.

Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Gustavo Romero <gromero@linux.ibm.com>
---
 tools/testing/selftests/powerpc/tm/tm-unavailable.c | 9 ++++++---
 tools/testing/selftests/powerpc/tm/tm.h             | 9 +++++++++
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/powerpc/tm/tm-unavailable.c b/tools/testing/selftests/powerpc/tm/tm-unavailable.c
index 156c8e750259..09894f4ff62e 100644
--- a/tools/testing/selftests/powerpc/tm/tm-unavailable.c
+++ b/tools/testing/selftests/powerpc/tm/tm-unavailable.c
@@ -236,7 +236,8 @@ void *tm_una_ping(void *input)
 	}
 
 	/* Check if we were not expecting a failure and a it occurred. */
-	if (!expecting_failure() && is_failure(cr_)) {
+	if (!expecting_failure() && is_failure(cr_) &&
+	    !failure_is_reschedule()) {
 		printf("\n\tUnexpected transaction failure 0x%02lx\n\t",
 			failure_code());
 		return (void *) -1;
@@ -244,9 +245,11 @@ void *tm_una_ping(void *input)
 
 	/*
 	 * Check if TM failed due to the cause we were expecting. 0xda is a
-	 * TM_CAUSE_FAC_UNAV cause, otherwise it's an unexpected cause.
+	 * TM_CAUSE_FAC_UNAV cause, otherwise it's an unexpected cause, unless
+	 * it was caused by a reschedule.
 	 */
-	if (is_failure(cr_) && !failure_is_unavailable()) {
+	if (is_failure(cr_) && !failure_is_unavailable() &&
+	    !failure_is_reschedule()) {
 		printf("\n\tUnexpected failure cause 0x%02lx\n\t",
 			failure_code());
 		return (void *) -1;
diff --git a/tools/testing/selftests/powerpc/tm/tm.h b/tools/testing/selftests/powerpc/tm/tm.h
index df4204247d45..5518b1d4ef8b 100644
--- a/tools/testing/selftests/powerpc/tm/tm.h
+++ b/tools/testing/selftests/powerpc/tm/tm.h
@@ -52,6 +52,15 @@ static inline bool failure_is_unavailable(void)
 	return (failure_code() & TM_CAUSE_FAC_UNAV) == TM_CAUSE_FAC_UNAV;
 }
 
+static inline bool failure_is_reschedule(void)
+{
+	if ((failure_code() & TM_CAUSE_RESCHED) == TM_CAUSE_RESCHED ||
+	    (failure_code() & TM_CAUSE_KVM_RESCHED) == TM_CAUSE_KVM_RESCHED)
+		return true;
+
+	return false;
+}
+
 static inline bool failure_is_nesting(void)
 {
 	return (__builtin_get_texasru() & 0x400000);
-- 
2.19.0

Re: [v2] selftests/powerpc: Do not fail with reschedule

[Michael Ellerman]

On Wed, 2018-09-12 at 20:31:05 UTC, Breno Leitao wrote:
> There are cases where the test is not expecting to have the transaction
> aborted, but, the test process might have been rescheduled, either in the
> OS level or by KVM (if it is running on a KVM guest machine). The process
> reschedule will cause a treclaim/recheckpoint which will cause the
> transaction to doom, aborting the transaction as soon as the process is
> rescheduled back to the CPU. This might cause the test to fail, but this is
> not a failure in essence.
> 
> If that is the case, TEXASR[FC] is indicated with either
> TM_CAUSE_RESCHEDULE or TM_CAUSE_KVM_RESCHEDULE for KVM interruptions.
> 
> In this scenario, ignore these two failures and avoid the whole test to
> return failure.
> 
> Signed-off-by: Breno Leitao <leitao@debian.org>
> Reviewed-by: Gustavo Romero <gromero@linux.ibm.com>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/44d947eff19d64384efc06069509db

cheers