[PATCH igt] lib: Force global reset + uevents for hang detector

[PATCH igt] lib: Force global reset + uevents for hang detector

[Chris Wilson]

The hang detector relies on a uevent for notification and aborting the
test. As proposed, fine-grained resets may not produce a global uevent
and so this hang detection becomes void. As we don't expect any hang, we
can just reduce the reset to only a global + uevent and so maintain
functionality, and switch back to fine-grained resets afterwards.

Note that any test that requires testing fine-grained resets should
ensure that they are enabled first as igt may leave the global
parameters in an inconsistent state.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
cc: Michel Thierr <michel.thierry@intel.com>
---
 lib/igt_aux.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/lib/igt_aux.c b/lib/igt_aux.c
index 1222806c..ca2feac3 100644
--- a/lib/igt_aux.c
+++ b/lib/igt_aux.c
@@ -60,6 +60,7 @@
 #include "igt_debugfs.h"
 #include "igt_gt.h"
 #include "igt_rand.h"
+#include "igt_sysfs.h"
 #include "config.h"
 #include "intel_reg.h"
 #include "ioctl_wrappers.h"
@@ -443,12 +444,34 @@ static void sig_abort(int sig)
 	igt_assert(!"GPU hung");
 }
 
+static bool set_parameter(int fd, const char *parameter, int value)
+{
+	int dir;
+
+	dir = igt_sysfs_open_parameters(fd);
+	if (dir < 0)
+		return false;
+
+	igt_sysfs_printf(dir, parameter, "%d", value);
+	close(dir);
+
+	return true;
+}
+
 void igt_fork_hang_detector(int fd)
 {
 	struct stat st;
 
 	igt_assert(fstat(fd, &st) == 0);
 
+	/*
+	 * Disable per-engine reset to force an error uevent. We don't
+	 * expect to get any hangs whilst the detector is enabled (if we do
+	 * they are a test failure!) and so the loss of per-engine reset
+	 * functionality is not an issue.
+	 */
+	igt_assert(set_parameter(fd, "reset", 1 /* global reset only */));
+
 	signal(SIGIO, sig_abort);
 	igt_fork_helper(&hang_detector)
 		hang_detector_process(getppid(), st.st_rdev);
-- 
2.11.0

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Re: [PATCH igt] lib: Force global reset + uevents for hang detector

[Mika Kuoppala]

Chris Wilson <chris@chris-wilson.co.uk> writes:

> The hang detector relies on a uevent for notification and aborting the
> test. As proposed, fine-grained resets may not produce a global uevent
> and so this hang detection becomes void. As we don't expect any hang, we
> can just reduce the reset to only a global + uevent and so maintain
> functionality, and switch back to fine-grained resets afterwards.
>
> Note that any test that requires testing fine-grained resets should
> ensure that they are enabled first as igt may leave the global
> parameters in an inconsistent state.
>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> cc: Michel Thierr <michel.thierry@intel.com>
+y

> ---
>  lib/igt_aux.c | 23 +++++++++++++++++++++++
>  1 file changed, 23 insertions(+)
>
> diff --git a/lib/igt_aux.c b/lib/igt_aux.c
> index 1222806c..ca2feac3 100644
> --- a/lib/igt_aux.c
> +++ b/lib/igt_aux.c
> @@ -60,6 +60,7 @@
>  #include "igt_debugfs.h"
>  #include "igt_gt.h"
>  #include "igt_rand.h"
> +#include "igt_sysfs.h"
>  #include "config.h"
>  #include "intel_reg.h"
>  #include "ioctl_wrappers.h"
> @@ -443,12 +444,34 @@ static void sig_abort(int sig)
>  	igt_assert(!"GPU hung");
>  }
>  
> +static bool set_parameter(int fd, const char *parameter, int value)
> +{
> +	int dir;
> +
> +	dir = igt_sysfs_open_parameters(fd);
> +	if (dir < 0)
> +		return false;
> +
> +	igt_sysfs_printf(dir, parameter, "%d", value);
> +	close(dir);
> +
> +	return true;
> +}
> +
>  void igt_fork_hang_detector(int fd)
>  {
>  	struct stat st;
>  
>  	igt_assert(fstat(fd, &st) == 0);
>  
> +	/*
> +	 * Disable per-engine reset to force an error uevent. We don't
> +	 * expect to get any hangs whilst the detector is enabled (if we do
> +	 * they are a test failure!) and so the loss of per-engine reset
> +	 * functionality is not an issue.
> +	 */

Makes sense. Tho I only looked one test which disables
hang detector before starting the more fine grained hang tests.

-Mika

> +	igt_assert(set_parameter(fd, "reset", 1 /* global reset only */));
> +
>  	signal(SIGIO, sig_abort);
>  	igt_fork_helper(&hang_detector)
>  		hang_detector_process(getppid(), st.st_rdev);
> -- 
> 2.11.0
>
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> Intel-gfx@lists.freedesktop.org
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Re: [PATCH igt] lib: Force global reset + uevents for hang detector

[Chris Wilson]

Quoting Mika Kuoppala (2017-06-05 12:15:15)
> Chris Wilson <chris@chris-wilson.co.uk> writes:
> 
> > The hang detector relies on a uevent for notification and aborting the
> > test. As proposed, fine-grained resets may not produce a global uevent
> > and so this hang detection becomes void. As we don't expect any hang, we
> > can just reduce the reset to only a global + uevent and so maintain
> > functionality, and switch back to fine-grained resets afterwards.
> >
> > Note that any test that requires testing fine-grained resets should
> > ensure that they are enabled first as igt may leave the global
> > parameters in an inconsistent state.
> >
> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > cc: Michel Thierr <michel.thierry@intel.com>
> +y
> 
> > ---
> >  lib/igt_aux.c | 23 +++++++++++++++++++++++
> >  1 file changed, 23 insertions(+)
> >
> > diff --git a/lib/igt_aux.c b/lib/igt_aux.c
> > index 1222806c..ca2feac3 100644
> > --- a/lib/igt_aux.c
> > +++ b/lib/igt_aux.c
> > @@ -60,6 +60,7 @@
> >  #include "igt_debugfs.h"
> >  #include "igt_gt.h"
> >  #include "igt_rand.h"
> > +#include "igt_sysfs.h"
> >  #include "config.h"
> >  #include "intel_reg.h"
> >  #include "ioctl_wrappers.h"
> > @@ -443,12 +444,34 @@ static void sig_abort(int sig)
> >       igt_assert(!"GPU hung");
> >  }
> >  
> > +static bool set_parameter(int fd, const char *parameter, int value)
> > +{
> > +     int dir;
> > +
> > +     dir = igt_sysfs_open_parameters(fd);
> > +     if (dir < 0)
> > +             return false;
> > +
> > +     igt_sysfs_printf(dir, parameter, "%d", value);
> > +     close(dir);
> > +
> > +     return true;
> > +}
> > +
> >  void igt_fork_hang_detector(int fd)
> >  {
> >       struct stat st;
> >  
> >       igt_assert(fstat(fd, &st) == 0);
> >  
> > +     /*
> > +      * Disable per-engine reset to force an error uevent. We don't
> > +      * expect to get any hangs whilst the detector is enabled (if we do
> > +      * they are a test failure!) and so the loss of per-engine reset
> > +      * functionality is not an issue.
> > +      */
> 
> Makes sense. Tho I only looked one test which disables
> hang detector before starting the more fine grained hang tests.

I did at first do a set_parameter("reset", INT_MAX) on
stop_hang_detector, but lacked the fd and didn't face wiring it up. So I
decided that any test that actually wants to test per-engine resets
should take of enabling per-engine resets first.

I guess igt_allow_hang() should do the inverse. That makes sense to me.
-Chris
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Re: [PATCH igt] lib: Force global reset + uevents for hang detector

[Chris Wilson]

Quoting Mika Kuoppala (2017-06-05 12:15:15)
> Chris Wilson <chris@chris-wilson.co.uk> writes:
> > +     /*
> > +      * Disable per-engine reset to force an error uevent. We don't
> > +      * expect to get any hangs whilst the detector is enabled (if we do
> > +      * they are a test failure!) and so the loss of per-engine reset
> > +      * functionality is not an issue.
> > +      */
> 
> Makes sense. Tho I only looked one test which disables
> hang detector before starting the more fine grained hang tests.

The alternative is that we send an error uevent for per-engine resets.
But I think that's overkill for TDR, and we want to keep as much as
possible generic. :|
-Chris
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[PATCH igt v2] lib: Force global reset + uevents for hang detector

[Chris Wilson]

The hang detector relies on a uevent for notification and aborting the
test. As proposed, fine-grained resets may not produce a global uevent
and so this hang detection becomes void. As we don't expect any hang, we
can just reduce the reset to only a global + uevent and so maintain
functionality, and switch back to fine-grained resets afterwards.

Note that any test that requires testing fine-grained resets should
ensure that they are enabled first as igt may leave the global
parameters in an inconsistent state.

v2: Restore fine-grained resets for explict igt_allow_hang()

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michel Thierry <michel.thierry@intel.com>
---
 lib/igt_aux.c   | 10 ++++++++
 lib/igt_gt.c    |  4 ++++
 lib/igt_sysfs.c | 72 ++++++++++++++++++++++++++++++++++++++++++---------------
 lib/igt_sysfs.h |  6 +++++
 4 files changed, 74 insertions(+), 18 deletions(-)

diff --git a/lib/igt_aux.c b/lib/igt_aux.c
index 1222806c..b1b63db5 100644
--- a/lib/igt_aux.c
+++ b/lib/igt_aux.c
@@ -60,6 +60,7 @@
 #include "igt_debugfs.h"
 #include "igt_gt.h"
 #include "igt_rand.h"
+#include "igt_sysfs.h"
 #include "config.h"
 #include "intel_reg.h"
 #include "ioctl_wrappers.h"
@@ -449,6 +450,15 @@ void igt_fork_hang_detector(int fd)
 
 	igt_assert(fstat(fd, &st) == 0);
 
+	/*
+	 * Disable per-engine reset to force an error uevent. We don't
+	 * expect to get any hangs whilst the detector is enabled (if we do
+	 * they are a test failure!) and so the loss of per-engine reset
+	 * functionality is not an issue.
+	 */
+	igt_assert(igt_sysfs_set_parameter
+		   (fd, "reset", "%d", 1 /* only global reset */));
+
 	signal(SIGIO, sig_abort);
 	igt_fork_helper(&hang_detector)
 		hang_detector_process(getppid(), st.st_rdev);
diff --git a/lib/igt_gt.c b/lib/igt_gt.c
index 11643edd..65743d07 100644
--- a/lib/igt_gt.c
+++ b/lib/igt_gt.c
@@ -21,6 +21,7 @@
  * IN THE SOFTWARE.
  */
 
+#include <limits.h>
 #include <string.h>
 #include <signal.h>
 #include <errno.h>
@@ -161,6 +162,9 @@ igt_hang_t igt_allow_hang(int fd, unsigned ctx, unsigned flags)
 	struct local_i915_gem_context_param param;
 	unsigned ban;
 
+	igt_assert(igt_sysfs_set_parameter
+		   (fd, "reset", "%d", INT_MAX /* any reset method */));
+
 	if (!igt_check_boolean_env_var("IGT_HANG", true))
 		igt_skip("hang injection disabled by user");
 	gem_context_require_bannable(fd);
diff --git a/lib/igt_sysfs.c b/lib/igt_sysfs.c
index 8ebc5b4f..15ed34be 100644
--- a/lib/igt_sysfs.c
+++ b/lib/igt_sysfs.c
@@ -139,6 +139,35 @@ int igt_sysfs_open(int device, int *idx)
 }
 
 /**
+ * igt_sysfs_set_parameters:
+ * @device: fd of the device (or -1 to default to Intel)
+ * @parameter: the name of the parameter to set
+ * @fmt: printf-esque format string
+ *
+ * Returns true on success
+ */
+bool igt_sysfs_set_parameter(int device,
+			     const char *parameter,
+			     const char *fmt, ...)
+{
+	va_list ap;
+	int dir;
+	int ret;
+
+	dir = igt_sysfs_open_parameters(device);
+	if (dir < 0)
+		return false;
+
+	va_start(ap, fmt);
+	ret = igt_sysfs_vprintf(dir, parameter, fmt, ap);
+	va_end(ap);
+
+	close(dir);
+
+	return ret > 0;
+}
+
+/**
  * igt_sysfs_open_parameters:
  * @device: fd of the device (or -1 to default to Intel)
  *
@@ -336,19 +365,7 @@ int igt_sysfs_scanf(int dir, const char *attr, const char *fmt, ...)
 	return ret;
 }
 
-/**
- * igt_sysfs_printf:
- * @dir: directory for the device from igt_sysfs_open()
- * @attr: name of the sysfs node to open
- * @fmt: printf format string
- * @...: Additional paramaters to store the scaned input values
- *
- * printf() wrapper for sysfs.
- * 
- * Returns:
- * Number of characters written, negative value on error.
- */
-int igt_sysfs_printf(int dir, const char *attr, const char *fmt, ...)
+int igt_sysfs_vprintf(int dir, const char *attr, const char *fmt, va_list ap)
 {
 	FILE *file;
 	int fd;
@@ -360,12 +377,7 @@ int igt_sysfs_printf(int dir, const char *attr, const char *fmt, ...)
 
 	file = fdopen(fd, "w");
 	if (file) {
-		va_list ap;
-
-		va_start(ap, fmt);
 		ret = vfprintf(file, fmt, ap);
-		va_end(ap);
-
 		fclose(file);
 	}
 	close(fd);
@@ -374,6 +386,30 @@ int igt_sysfs_printf(int dir, const char *attr, const char *fmt, ...)
 }
 
 /**
+ * igt_sysfs_printf:
+ * @dir: directory for the device from igt_sysfs_open()
+ * @attr: name of the sysfs node to open
+ * @fmt: printf format string
+ * @...: Additional paramaters to store the scaned input values
+ *
+ * printf() wrapper for sysfs.
+ *
+ * Returns:
+ * Number of characters written, negative value on error.
+ */
+int igt_sysfs_printf(int dir, const char *attr, const char *fmt, ...)
+{
+	va_list ap;
+	int ret;
+
+	va_start(ap, fmt);
+	ret = igt_sysfs_vprintf(dir, attr, fmt, ap);
+	va_end(ap);
+
+	return ret;
+}
+
+/**
  * igt_sysfs_get_u32:
  * @dir: directory for the device from igt_sysfs_open()
  * @attr: name of the sysfs node to open
diff --git a/lib/igt_sysfs.h b/lib/igt_sysfs.h
index 4089535d..d666438a 100644
--- a/lib/igt_sysfs.h
+++ b/lib/igt_sysfs.h
@@ -29,6 +29,10 @@
 
 int igt_sysfs_open(int device, int *idx);
 int igt_sysfs_open_parameters(int device);
+bool igt_sysfs_set_parameter(int device,
+			     const char *parameter,
+			     const char *fmt, ...)
+	__attribute__((format(printf,3,4)));
 
 int igt_sysfs_read(int dir, const char *attr, void *data, int len);
 int igt_sysfs_write(int dir, const char *attr, const void *data, int len);
@@ -38,6 +42,8 @@ char *igt_sysfs_get(int dir, const char *attr);
 
 int igt_sysfs_scanf(int dir, const char *attr, const char *fmt, ...)
 	__attribute__((format(scanf,3,4)));
+int igt_sysfs_vprintf(int dir, const char *attr, const char *fmt, va_list ap)
+	__attribute__((format(printf,3,0)));
 int igt_sysfs_printf(int dir, const char *attr, const char *fmt, ...)
 	__attribute__((format(printf,3,4)));
 
-- 
2.11.0

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Re: [PATCH igt v2] lib: Force global reset + uevents for hang detector

[Michel Thierry]

On 6/5/2017 5:13 AM, Chris Wilson wrote:
> The hang detector relies on a uevent for notification and aborting the
> test. As proposed, fine-grained resets may not produce a global uevent
> and so this hang detection becomes void. As we don't expect any hang, we
> can just reduce the reset to only a global + uevent and so maintain
> functionality, and switch back to fine-grained resets afterwards.
> 
> Note that any test that requires testing fine-grained resets should
> ensure that they are enabled first as igt may leave the global
> parameters in an inconsistent state.
> 
> v2: Restore fine-grained resets for explict igt_allow_hang()
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Michel Thierry <michel.thierry@intel.com>
> ---
>   lib/igt_aux.c   | 10 ++++++++
>   lib/igt_gt.c    |  4 ++++
>   lib/igt_sysfs.c | 72 ++++++++++++++++++++++++++++++++++++++++++---------------
>   lib/igt_sysfs.h |  6 +++++
>   4 files changed, 74 insertions(+), 18 deletions(-)
> 
> diff --git a/lib/igt_aux.c b/lib/igt_aux.c
> index 1222806c..b1b63db5 100644
> --- a/lib/igt_aux.c
> +++ b/lib/igt_aux.c
> @@ -60,6 +60,7 @@
>   #include "igt_debugfs.h"
>   #include "igt_gt.h"
>   #include "igt_rand.h"
> +#include "igt_sysfs.h"
>   #include "config.h"
>   #include "intel_reg.h"
>   #include "ioctl_wrappers.h"
> @@ -449,6 +450,15 @@ void igt_fork_hang_detector(int fd)
>   
>   	igt_assert(fstat(fd, &st) == 0);
>   
> +	/*
> +	 * Disable per-engine reset to force an error uevent. We don't
> +	 * expect to get any hangs whilst the detector is enabled (if we do
> +	 * they are a test failure!) and so the loss of per-engine reset
> +	 * functionality is not an issue.
> +	 */
> +	igt_assert(igt_sysfs_set_parameter
> +		   (fd, "reset", "%d", 1 /* only global reset */));
> +
>   	signal(SIGIO, sig_abort);
>   	igt_fork_helper(&hang_detector)
>   		hang_detector_process(getppid(), st.st_rdev);

I think the stop_hang_detector needs to restore the 'reset' value too, 
or subsequent tests (using igt_hang_ctx) would only have global reset;

@@ -457,6 +457,8 @@ void igt_fork_hang_detector(int fd)
  void igt_stop_hang_detector(void)
  {
  	igt_stop_helper(&hang_detector);
+	igt_assert(igt_sysfs_set_parameter
+		   (fd, "reset", "%d", INT_MAX /* any reset method */));
  }
  #else
  void igt_fork_hang_detector(int fd)


> diff --git a/lib/igt_gt.c b/lib/igt_gt.c
> index 11643edd..65743d07 100644
> --- a/lib/igt_gt.c
> +++ b/lib/igt_gt.c
> @@ -21,6 +21,7 @@
>    * IN THE SOFTWARE.
>    */
>   
> +#include <limits.h>
>   #include <string.h>
>   #include <signal.h>
>   #include <errno.h>
> @@ -161,6 +162,9 @@ igt_hang_t igt_allow_hang(int fd, unsigned ctx, unsigned flags)
>   	struct local_i915_gem_context_param param;
>   	unsigned ban;
>   
> +	igt_assert(igt_sysfs_set_parameter
> +		   (fd, "reset", "%d", INT_MAX /* any reset method */));
> +
>   	if (!igt_check_boolean_env_var("IGT_HANG", true))
>   		igt_skip("hang injection disabled by user");
>   	gem_context_require_bannable(fd);
> diff --git a/lib/igt_sysfs.c b/lib/igt_sysfs.c
> index 8ebc5b4f..15ed34be 100644
> --- a/lib/igt_sysfs.c
> +++ b/lib/igt_sysfs.c
> @@ -139,6 +139,35 @@ int igt_sysfs_open(int device, int *idx)
>   }
>   
>   /**
> + * igt_sysfs_set_parameters:
> + * @device: fd of the device (or -1 to default to Intel)
> + * @parameter: the name of the parameter to set
> + * @fmt: printf-esque format string
> + *
> + * Returns true on success
> + */
> +bool igt_sysfs_set_parameter(int device,
> +			     const char *parameter,
> +			     const char *fmt, ...)
> +{
> +	va_list ap;
> +	int dir;
> +	int ret;
> +
> +	dir = igt_sysfs_open_parameters(device);
> +	if (dir < 0)
> +		return false;
> +
> +	va_start(ap, fmt);
> +	ret = igt_sysfs_vprintf(dir, parameter, fmt, ap);
> +	va_end(ap);
> +
> +	close(dir);
> +
> +	return ret > 0;
> +}
> +
> +/**
>    * igt_sysfs_open_parameters:
>    * @device: fd of the device (or -1 to default to Intel)
>    *
> @@ -336,19 +365,7 @@ int igt_sysfs_scanf(int dir, const char *attr, const char *fmt, ...)
>   	return ret;
>   }
>   
> -/**
> - * igt_sysfs_printf:
> - * @dir: directory for the device from igt_sysfs_open()
> - * @attr: name of the sysfs node to open
> - * @fmt: printf format string
> - * @...: Additional paramaters to store the scaned input values
> - *
> - * printf() wrapper for sysfs.
> - *
> - * Returns:
> - * Number of characters written, negative value on error.
> - */
> -int igt_sysfs_printf(int dir, const char *attr, const char *fmt, ...)
> +int igt_sysfs_vprintf(int dir, const char *attr, const char *fmt, va_list ap)
>   {
>   	FILE *file;
>   	int fd;
> @@ -360,12 +377,7 @@ int igt_sysfs_printf(int dir, const char *attr, const char *fmt, ...)
>   
>   	file = fdopen(fd, "w");
>   	if (file) {
> -		va_list ap;
> -
> -		va_start(ap, fmt);
>   		ret = vfprintf(file, fmt, ap);
> -		va_end(ap);
> -
>   		fclose(file);
>   	}
>   	close(fd);
> @@ -374,6 +386,30 @@ int igt_sysfs_printf(int dir, const char *attr, const char *fmt, ...)
>   }
>   
>   /**
> + * igt_sysfs_printf:
> + * @dir: directory for the device from igt_sysfs_open()
> + * @attr: name of the sysfs node to open
> + * @fmt: printf format string
> + * @...: Additional paramaters to store the scaned input values
> + *
> + * printf() wrapper for sysfs.
> + *
> + * Returns:
> + * Number of characters written, negative value on error.
> + */
> +int igt_sysfs_printf(int dir, const char *attr, const char *fmt, ...)
> +{
> +	va_list ap;
> +	int ret;
> +
> +	va_start(ap, fmt);
> +	ret = igt_sysfs_vprintf(dir, attr, fmt, ap);
> +	va_end(ap);
> +
> +	return ret;
> +}
> +
> +/**
>    * igt_sysfs_get_u32:
>    * @dir: directory for the device from igt_sysfs_open()
>    * @attr: name of the sysfs node to open
> diff --git a/lib/igt_sysfs.h b/lib/igt_sysfs.h
> index 4089535d..d666438a 100644
> --- a/lib/igt_sysfs.h
> +++ b/lib/igt_sysfs.h
> @@ -29,6 +29,10 @@
>   
>   int igt_sysfs_open(int device, int *idx);
>   int igt_sysfs_open_parameters(int device);
> +bool igt_sysfs_set_parameter(int device,
> +			     const char *parameter,
> +			     const char *fmt, ...)
> +	__attribute__((format(printf,3,4)));
>   
>   int igt_sysfs_read(int dir, const char *attr, void *data, int len);
>   int igt_sysfs_write(int dir, const char *attr, const void *data, int len);
> @@ -38,6 +42,8 @@ char *igt_sysfs_get(int dir, const char *attr);
>   
>   int igt_sysfs_scanf(int dir, const char *attr, const char *fmt, ...)
>   	__attribute__((format(scanf,3,4)));
> +int igt_sysfs_vprintf(int dir, const char *attr, const char *fmt, va_list ap)
> +	__attribute__((format(printf,3,0)));
>   int igt_sysfs_printf(int dir, const char *attr, const char *fmt, ...)
>   	__attribute__((format(printf,3,4)));
>   
> 
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Re: [PATCH igt v2] lib: Force global reset + uevents for hang detector

[Chris Wilson]

Quoting Michel Thierry (2017-06-05 22:21:48)
> On 6/5/2017 5:13 AM, Chris Wilson wrote:
> > The hang detector relies on a uevent for notification and aborting the
> > test. As proposed, fine-grained resets may not produce a global uevent
> > and so this hang detection becomes void. As we don't expect any hang, we
> > can just reduce the reset to only a global + uevent and so maintain
> > functionality, and switch back to fine-grained resets afterwards.
> > 
> > Note that any test that requires testing fine-grained resets should
> > ensure that they are enabled first as igt may leave the global
> > parameters in an inconsistent state.
> > 
> > v2: Restore fine-grained resets for explict igt_allow_hang()
> > 
> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Cc: Michel Thierry <michel.thierry@intel.com>
> > ---
> >   lib/igt_aux.c   | 10 ++++++++
> >   lib/igt_gt.c    |  4 ++++
> >   lib/igt_sysfs.c | 72 ++++++++++++++++++++++++++++++++++++++++++---------------
> >   lib/igt_sysfs.h |  6 +++++
> >   4 files changed, 74 insertions(+), 18 deletions(-)
> > 
> > diff --git a/lib/igt_aux.c b/lib/igt_aux.c
> > index 1222806c..b1b63db5 100644
> > --- a/lib/igt_aux.c
> > +++ b/lib/igt_aux.c
> > @@ -60,6 +60,7 @@
> >   #include "igt_debugfs.h"
> >   #include "igt_gt.h"
> >   #include "igt_rand.h"
> > +#include "igt_sysfs.h"
> >   #include "config.h"
> >   #include "intel_reg.h"
> >   #include "ioctl_wrappers.h"
> > @@ -449,6 +450,15 @@ void igt_fork_hang_detector(int fd)
> >   
> >       igt_assert(fstat(fd, &st) == 0);
> >   
> > +     /*
> > +      * Disable per-engine reset to force an error uevent. We don't
> > +      * expect to get any hangs whilst the detector is enabled (if we do
> > +      * they are a test failure!) and so the loss of per-engine reset
> > +      * functionality is not an issue.
> > +      */
> > +     igt_assert(igt_sysfs_set_parameter
> > +                (fd, "reset", "%d", 1 /* only global reset */));
> > +
> >       signal(SIGIO, sig_abort);
> >       igt_fork_helper(&hang_detector)
> >               hang_detector_process(getppid(), st.st_rdev);
> 
> I think the stop_hang_detector needs to restore the 'reset' value too, 
> or subsequent tests (using igt_hang_ctx) would only have global reset;

There's nothing fundamentally wrong with that... The problem is that we
are introducing a second reset path, and so anything that is testing
resets should ideally exercise both. :| That's where I was going with
my comments about this leaving igt in an inconsistent state and that we
should specify which path we want to test when we do the tests.
-Chris
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Re: [PATCH igt v2] lib: Force global reset + uevents for hang detector

[Michel Thierry]

On 6/5/2017 3:57 PM, Chris Wilson wrote:
> Quoting Michel Thierry (2017-06-05 22:21:48)
>> On 6/5/2017 5:13 AM, Chris Wilson wrote:
>>> The hang detector relies on a uevent for notification and aborting the
>>> test. As proposed, fine-grained resets may not produce a global uevent
>>> and so this hang detection becomes void. As we don't expect any hang, we
>>> can just reduce the reset to only a global + uevent and so maintain
>>> functionality, and switch back to fine-grained resets afterwards.
>>>
>>> Note that any test that requires testing fine-grained resets should
>>> ensure that they are enabled first as igt may leave the global
>>> parameters in an inconsistent state.
>>>
>>> v2: Restore fine-grained resets for explict igt_allow_hang()
>>>
>>> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
>>> Cc: Michel Thierry <michel.thierry@intel.com>
>>> ---
>>>    lib/igt_aux.c   | 10 ++++++++
>>>    lib/igt_gt.c    |  4 ++++
>>>    lib/igt_sysfs.c | 72 ++++++++++++++++++++++++++++++++++++++++++---------------
>>>    lib/igt_sysfs.h |  6 +++++
>>>    4 files changed, 74 insertions(+), 18 deletions(-)
>>>
>>> diff --git a/lib/igt_aux.c b/lib/igt_aux.c
>>> index 1222806c..b1b63db5 100644
>>> --- a/lib/igt_aux.c
>>> +++ b/lib/igt_aux.c
>>> @@ -60,6 +60,7 @@
>>>    #include "igt_debugfs.h"
>>>    #include "igt_gt.h"
>>>    #include "igt_rand.h"
>>> +#include "igt_sysfs.h"
>>>    #include "config.h"
>>>    #include "intel_reg.h"
>>>    #include "ioctl_wrappers.h"
>>> @@ -449,6 +450,15 @@ void igt_fork_hang_detector(int fd)
>>>    
>>>        igt_assert(fstat(fd, &st) == 0);
>>>    
>>> +     /*
>>> +      * Disable per-engine reset to force an error uevent. We don't
>>> +      * expect to get any hangs whilst the detector is enabled (if we do
>>> +      * they are a test failure!) and so the loss of per-engine reset
>>> +      * functionality is not an issue.
>>> +      */
>>> +     igt_assert(igt_sysfs_set_parameter
>>> +                (fd, "reset", "%d", 1 /* only global reset */));
>>> +
>>>        signal(SIGIO, sig_abort);
>>>        igt_fork_helper(&hang_detector)
>>>                hang_detector_process(getppid(), st.st_rdev);
>>
>> I think the stop_hang_detector needs to restore the 'reset' value too,
>> or subsequent tests (using igt_hang_ctx) would only have global reset;
> 
> There's nothing fundamentally wrong with that... The problem is that we
> are introducing a second reset path, and so anything that is testing
> resets should ideally exercise both. :| That's where I was going with
> my comments about this leaving igt in an inconsistent state and that we
> should specify which path we want to test when we do the tests.

Ok, I agree "reset tests" should either exercise both or explicitly set 
if they want engine or global reset. Other tests that just require a 
hang subtest can use either one.

The caveat would be display's hung subtests, but I noticed they write -1 
to i915_wedged, and that will trigger a global reset anyway.

Reviewed-by: Michel Thierry <michel.thierry@intel.com>
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