[PATCH v3 0/3] Make fault injection available for MMC IO

[PATCH v3 0/3] Make fault injection available for MMC IO

[Per Forlin]

The first version of this patch is a part of mmc non-blocking v9 patchset:
[PATCH v9 11/12] mmc: core: add random fault injection

change log:
 v2 - Resolve build issue in mmc core.c due to multiple init_module by
      removing the fault inject module.
    - Export fault injection functions to make them available for modules
    - Update fault injection documentation on MMC IO  
 v3 - add function descriptions in core.c
    - use export GPL for fault injection functions

Per Forlin (3):
  fault-inject: make fault injection available for modules
  mmc: core: add random fault injection
  fault injection: add documentation on MMC IO fault injection

 Documentation/fault-injection/fault-injection.txt |    5 ++
 drivers/mmc/core/core.c                           |   69 +++++++++++++++++++++
 drivers/mmc/core/debugfs.c                        |    5 ++
 include/linux/mmc/host.h                          |    3 +
 lib/Kconfig.debug                                 |   11 +++
 lib/fault-inject.c                                |    2 +
 6 files changed, 95 insertions(+), 0 deletions(-)

-- 
1.7.4.1

[PATCH v3 1/3] fault-inject: make fault injection available for modules

[Per Forlin]

export symbols should_fail() and init_fault_attr_dentries() in order
to make modules use the fault injection functionality

Signed-off-by: Per Forlin <per.forlin@linaro.org>
---
 lib/fault-inject.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/lib/fault-inject.c b/lib/fault-inject.c
index 7e65af7..27783da 100644
--- a/lib/fault-inject.c
+++ b/lib/fault-inject.c
@@ -131,6 +131,7 @@ bool should_fail(struct fault_attr *attr, ssize_t size)
 
 	return true;
 }
+EXPORT_SYMBOL_GPL(should_fail);
 
 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
 
@@ -311,5 +312,6 @@ fail:
 	cleanup_fault_attr_dentries(attr);
 	return -ENOMEM;
 }
+EXPORT_SYMBOL_GPL(init_fault_attr_dentries);
 
 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */
-- 
1.7.4.1

[PATCH v3 2/3] mmc: core: add random fault injection

[Per Forlin]

This adds support to inject data errors after a completed host transfer.
The mmc core will return error even though the host transfer is successful.
This simple fault injection proved to be very useful to test the
non-blocking error handling in the mmc_blk_issue_rw_rq().
Random faults can also test how the host driver handles pre_req()
and post_req() in case of errors.

Signed-off-by: Per Forlin <per.forlin@linaro.org>
---
 drivers/mmc/core/core.c    |   69 ++++++++++++++++++++++++++++++++++++++++++++
 drivers/mmc/core/debugfs.c |    5 +++
 include/linux/mmc/host.h   |    3 ++
 lib/Kconfig.debug          |   11 +++++++
 4 files changed, 88 insertions(+), 0 deletions(-)

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index ab36c7b..dac2673 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -24,6 +24,11 @@
 #include <linux/regulator/consumer.h>
 #include <linux/pm_runtime.h>
 
+#ifdef CONFIG_FAIL_MMC_REQUEST
+#include <linux/fault-inject.h>
+#include <linux/random.h>
+#endif
+
 #include <linux/mmc/card.h>
 #include <linux/mmc/host.h>
 #include <linux/mmc/mmc.h>
@@ -82,6 +87,66 @@ static void mmc_flush_scheduled_work(void)
 	flush_workqueue(workqueue);
 }
 
+#ifdef CONFIG_FAIL_MMC_REQUEST
+
+static DECLARE_FAULT_ATTR(fail_mmc_request);
+
+/*
+ * Internal function. Pass the boot param fail_mmc_request to
+ * the setup fault injection attributes routine.
+ */
+static int __init setup_fail_mmc_request(char *str)
+{
+	return setup_fault_attr(&fail_mmc_request, str);
+}
+__setup("fail_mmc_request=", setup_fail_mmc_request);
+
+/*
+ * Internal function. Inject random data errors.
+ * If mmc_data is NULL no errors are injected.
+ */
+static void mmc_should_fail_request(struct mmc_host *host,
+				    struct mmc_request *mrq)
+{
+	struct mmc_command *cmd = mrq->cmd;
+	struct mmc_data *data = mrq->data;
+	static const int data_errors[] = {
+		-ETIMEDOUT,
+		-EILSEQ,
+		-EIO,
+	};
+
+	if (!data)
+		return;
+
+	if (cmd->error || data->error || !host->make_it_fail ||
+	    !should_fail(&fail_mmc_request, data->blksz * data->blocks))
+		return;
+
+	data->error = data_errors[random32() % ARRAY_SIZE(data_errors)];
+	data->bytes_xfered = (random32() % (data->bytes_xfered >> 9)) << 9;
+}
+
+static int __init fail_mmc_request_debugfs(void)
+{
+	return init_fault_attr_dentries(&fail_mmc_request,
+					"fail_mmc_request");
+}
+
+#else /* CONFIG_FAIL_MMC_REQUEST */
+
+static void mmc_should_fail_request(struct mmc_host *host,
+				    struct mmc_request *mrq)
+{
+}
+
+static int __init fail_mmc_request_debugfs(void)
+{
+	return 0;
+}
+#endif /* CONFIG_FAIL_MMC_REQUEST */
+
+
 /**
  *	mmc_request_done - finish processing an MMC request
  *	@host: MMC host which completed request
@@ -108,6 +173,8 @@ void mmc_request_done(struct mmc_host *host, struct mmc_request *mrq)
 		cmd->error = 0;
 		host->ops->request(host, mrq);
 	} else {
+		mmc_should_fail_request(host, mrq);
+
 		led_trigger_event(host->led, LED_OFF);
 
 		pr_debug("%s: req done (CMD%u): %d: %08x %08x %08x %08x\n",
@@ -2064,6 +2131,8 @@ static int __init mmc_init(void)
 	if (ret)
 		goto unregister_host_class;
 
+	fail_mmc_request_debugfs();
+
 	return 0;
 
 unregister_host_class:
diff --git a/drivers/mmc/core/debugfs.c b/drivers/mmc/core/debugfs.c
index 998797e..588e76f 100644
--- a/drivers/mmc/core/debugfs.c
+++ b/drivers/mmc/core/debugfs.c
@@ -188,6 +188,11 @@ void mmc_add_host_debugfs(struct mmc_host *host)
 				root, &host->clk_delay))
 		goto err_node;
 #endif
+#ifdef CONFIG_FAIL_MMC_REQUEST
+	if (!debugfs_create_u8("make-it-fail", S_IRUSR | S_IWUSR,
+			       root, &host->make_it_fail))
+		goto err_node;
+#endif
 	return;
 
 err_node:
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 771455f..250b46d 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -303,6 +303,9 @@ struct mmc_host {
 
 	struct mmc_async_req	*areq;		/* active async req */
 
+#ifdef CONFIG_FAIL_MMC_REQUEST
+	u8			make_it_fail;
+#endif
 	unsigned long		private[0] ____cacheline_aligned;
 };
 
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index c768bcd..c2d1423 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1057,6 +1057,17 @@ config FAIL_IO_TIMEOUT
 	  Only works with drivers that use the generic timeout handling,
 	  for others it wont do anything.
 
+config FAIL_MMC_REQUEST
+	bool "Fault-injection capability for MMC IO"
+	select DEBUG_FS
+	depends on FAULT_INJECTION && MMC
+	help
+	  Provide fault-injection capability for MMC IO.
+	  This will make the mmc core return data errors. This is
+	  useful to test the error handling in the mmc block device
+	  and to test how the mmc host driver handles retries from
+	  the block device.
+
 config FAULT_INJECTION_DEBUG_FS
 	bool "Debugfs entries for fault-injection capabilities"
 	depends on FAULT_INJECTION && SYSFS && DEBUG_FS
-- 
1.7.4.1

[PATCH v3 2/3] mmc: core: add random fault injection

[Akinobu Mita]

2011/7/21 Per Forlin <per.forlin@linaro.org>:
> This adds support to inject data errors after a completed host transfer.
> The mmc core will return error even though the host transfer is successful.
> This simple fault injection proved to be very useful to test the
> non-blocking error handling in the mmc_blk_issue_rw_rq().
> Random faults can also test how the host driver handles pre_req()
> and post_req() in case of errors.

Looks good to me.

> @@ -82,6 +87,66 @@ static void mmc_flush_scheduled_work(void)
> ? ? ? ?flush_workqueue(workqueue);
> ?}
>
> +#ifdef CONFIG_FAIL_MMC_REQUEST
> +
> +static DECLARE_FAULT_ATTR(fail_mmc_request);

I think the fail_attr should be defined for each mmc_host like make_it_fail
in struct mmc_host and debugfs entries should also be created in a
subdirectory of mmc host debugfs.

And I know that init_fault_attr_dentries() can only create a
subdirectory in debugfs root directory.  But I have a patch which
support for creating it in arbitrary directory.  Could you take a look
at this? (Note that this patch is based on mmotm and not yet tested)
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[PATCH v3 2/3] mmc: core: add random fault injection

[Per Forlin]

On 25 July 2011 17:58, Akinobu Mita <akinobu.mita@gmail.com> wrote:
> 2011/7/21 Per Forlin <per.forlin@linaro.org>:
>> This adds support to inject data errors after a completed host transfer.
>> The mmc core will return error even though the host transfer is successful.
>> This simple fault injection proved to be very useful to test the
>> non-blocking error handling in the mmc_blk_issue_rw_rq().
>> Random faults can also test how the host driver handles pre_req()
>> and post_req() in case of errors.
>
> Looks good to me.
>
Thanks,

>> @@ -82,6 +87,66 @@ static void mmc_flush_scheduled_work(void)
>> ? ? ? ?flush_workqueue(workqueue);
>> ?}
>>
>> +#ifdef CONFIG_FAIL_MMC_REQUEST
>> +
>> +static DECLARE_FAULT_ATTR(fail_mmc_request);
>
> I think the fail_attr should be defined for each mmc_host like make_it_fail
> in struct mmc_host and debugfs entries should also be created in a
> subdirectory of mmc host debugfs.
>
I looked at blk-core.c and used the same code here. Current code
creates the entry under the debugfs root. This means one fail_attr for
all hosts.
I agree, it's more clean to move the fail_attr to the
host-debugfs-entry which require the fail_attr to be stored same way
as make_it_fail.

> And I know that init_fault_attr_dentries() can only create a
> subdirectory in debugfs root directory. ?But I have a patch which
> support for creating it in arbitrary directory. ?Could you take a look
> at this? (Note that this patch is based on mmotm and not yet tested)
>
Thanks, I will check it out.

Regards,
Per

[PATCH v3 2/3] mmc: core: add random fault injection

[Per Forlin]

Hi Akinobu,

On 25 July 2011 21:19, Per Forlin <per.forlin@linaro.org> wrote:
> On 25 July 2011 17:58, Akinobu Mita <akinobu.mita@gmail.com> wrote:
>> 2011/7/21 Per Forlin <per.forlin@linaro.org>:
>>> This adds support to inject data errors after a completed host transfer.
>>> The mmc core will return error even though the host transfer is successful.
>>> This simple fault injection proved to be very useful to test the
>>> non-blocking error handling in the mmc_blk_issue_rw_rq().
>>> Random faults can also test how the host driver handles pre_req()
>>> and post_req() in case of errors.
>>
>> Looks good to me.
>>
> Thanks,
>
>>> @@ -82,6 +87,66 @@ static void mmc_flush_scheduled_work(void)
>>> ? ? ? ?flush_workqueue(workqueue);
>>> ?}
>>>
>>> +#ifdef CONFIG_FAIL_MMC_REQUEST
>>> +
>>> +static DECLARE_FAULT_ATTR(fail_mmc_request);
>>
>> I think the fail_attr should be defined for each mmc_host like make_it_fail
>> in struct mmc_host and debugfs entries should also be created in a
>> subdirectory of mmc host debugfs.
>>
> I looked at blk-core.c and used the same code here. Current code
> creates the entry under the debugfs root. This means one fail_attr for
> all hosts.
> I agree, it's more clean to move the fail_attr to the
> host-debugfs-entry which require the fail_attr to be stored same way
> as make_it_fail.
>
>> And I know that init_fault_attr_dentries() can only create a
>> subdirectory in debugfs root directory. ?But I have a patch which
>> support for creating it in arbitrary directory. ?Could you take a look
>> at this? (Note that this patch is based on mmotm and not yet tested)
>>
I looked at your patch and it raised two questions.
I can't use FAULT_ATTR_INITIALIZER since mmc_host is allocated on the
heap. It looks like setup_fault_attr(attr, str) will fail if str is
NULL. How can I initialise the fault_attrs if not stack allocated?
About the boot param initialisation of fault attr. There can only be
one fault_mmc_request boot param for the entire kernel but there is
one fault_attr per host, and there may be many hosts. It would be
convenient if setup_fault_attrs would take (attr, boot_param_name),
look up boot_param_name and use that otherwise set default values.

Regards,
Per

[PATCH v3 2/3] mmc: core: add random fault injection

[Akinobu Mita]

2011/7/26 Per Forlin <per.forlin@linaro.org>:
>>> And I know that init_fault_attr_dentries() can only create a
>>> subdirectory in debugfs root directory. ?But I have a patch which
>>> support for creating it in arbitrary directory. ?Could you take a look
>>> at this? (Note that this patch is based on mmotm and not yet tested)
>>>
> I looked at your patch and it raised two questions.
> I can't use FAULT_ATTR_INITIALIZER since mmc_host is allocated on the
> heap. It looks like setup_fault_attr(attr, str) will fail if str is
> NULL. How can I initialise the fault_attrs if not stack allocated?
> About the boot param initialisation of fault attr. There can only be
> one fault_mmc_request boot param for the entire kernel but there is
> one fault_attr per host, and there may be many hosts. It would be
> convenient if setup_fault_attrs would take (attr, boot_param_name),
> look up boot_param_name and use that otherwise set default values.

I think you can define one default fail_attr for boot time configuration
and copy it to per-host fail_attr in mmc_add_host_debugfs().

/* pseudo-code */

static DECLARE_FAULT_ATTR(default_mmc_fail_attr);

static int __init setup_fail_mmc_request(char *str)
{
	return setup_fault_attr(&default_mmc_fail_attr, str);
}
__setup("fail_mmc_request=", setup_fail_mmc_request);

...

void mmc_add_host_debugfs(struct mmc_host *host)
{
	...

#ifdef CONFIG_FAIL_MMC_REQUEST
	host->fail_attr = default_mmc_fail_attr;
	if (!debugfs_create_fault_attr("fail_mmc_request",
					root, &host->fail_attr))
		goto err_node;
#endif
	...
}

[PATCH v3 2/3] mmc: core: add random fault injection

[Per Forlin]

On 26 July 2011 03:41, Akinobu Mita <akinobu.mita@gmail.com> wrote:
> 2011/7/26 Per Forlin <per.forlin@linaro.org>:
>>>> And I know that init_fault_attr_dentries() can only create a
>>>> subdirectory in debugfs root directory. ?But I have a patch which
>>>> support for creating it in arbitrary directory. ?Could you take a look
>>>> at this? (Note that this patch is based on mmotm and not yet tested)
>>>>
>> I looked at your patch and it raised two questions.
>> I can't use FAULT_ATTR_INITIALIZER since mmc_host is allocated on the
>> heap. It looks like setup_fault_attr(attr, str) will fail if str is
>> NULL. How can I initialise the fault_attrs if not stack allocated?
>> About the boot param initialisation of fault attr. There can only be
>> one fault_mmc_request boot param for the entire kernel but there is
>> one fault_attr per host, and there may be many hosts. It would be
>> convenient if setup_fault_attrs would take (attr, boot_param_name),
>> look up boot_param_name and use that otherwise set default values.
>
> I think you can define one default fail_attr for boot time configuration
> and copy it to per-host fail_attr in mmc_add_host_debugfs().
>
You're right. This works fine. I'll prepare a new version of my patch.

[PATCH v3 2/3] mmc: core: add random fault injection

[Per Forlin]

On 25 July 2011 17:58, Akinobu Mita <akinobu.mita@gmail.com> wrote:
> 2011/7/21 Per Forlin <per.forlin@linaro.org>:
>> This adds support to inject data errors after a completed host transfer.
>> The mmc core will return error even though the host transfer is successful.
>> This simple fault injection proved to be very useful to test the
>> non-blocking error handling in the mmc_blk_issue_rw_rq().
>> Random faults can also test how the host driver handles pre_req()
>> and post_req() in case of errors.
>
> Looks good to me.
>
>> @@ -82,6 +87,66 @@ static void mmc_flush_scheduled_work(void)
>> ? ? ? ?flush_workqueue(workqueue);
>> ?}
>>
>> +#ifdef CONFIG_FAIL_MMC_REQUEST
>> +
>> +static DECLARE_FAULT_ATTR(fail_mmc_request);
>
> I think the fail_attr should be defined for each mmc_host like make_it_fail
> in struct mmc_host and debugfs entries should also be created in a
> subdirectory of mmc host debugfs.
>
> And I know that init_fault_attr_dentries() can only create a
> subdirectory in debugfs root directory. ?But I have a patch which
> support for creating it in arbitrary directory. ?Could you take a look
> at this? (Note that this patch is based on mmotm and not yet tested)
>
I tested your patch on a Snowball board. I had two active mmc cards
and did various fault injection configurations on the two cards
together with dd. I did only test MMC IO fault injection and not any
of the other fault injection clients.
Tested-by: Per Forlin <per.forlin@linaro.org>

Regards,
Per

[PATCH v3 3/3] fault injection: add documentation on MMC IO fault injection

[Per Forlin]

Add description on how to enable random fault injection
for MMC IO

Signed-off-by: Per Forlin <per.forlin@linaro.org>
---
 Documentation/fault-injection/fault-injection.txt |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/Documentation/fault-injection/fault-injection.txt b/Documentation/fault-injection/fault-injection.txt
index 7be15e4..27eede4 100644
--- a/Documentation/fault-injection/fault-injection.txt
+++ b/Documentation/fault-injection/fault-injection.txt
@@ -21,6 +21,11 @@ o fail_make_request
   /sys/block/<device>/make-it-fail or
   /sys/block/<device>/<partition>/make-it-fail. (generic_make_request())
 
+o fail_mmc_request
+
+  injects MMC data errors on devices permitted by setting
+  /sys/kernel/debug/mmc0/make-it-fail
+
 Configure fault-injection capabilities behavior
 -----------------------------------------------
 
-- 
1.7.4.1