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@xxxxxxxxxx>
---
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
--
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