This simple fault injection proved to be very useful to
test the error handling in the block.c rw_rq(). It may
still be useful to test if the host driver handle
pre_req() and post_req() correctly in case of errors.

Signed-off-by: Per Forlin <redacted>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Venkatraman S <redacted>
Tested-by: Sourav Poddar<redacted>
Tested-by: Linus Walleij <redacted>
---
?drivers/mmc/core/core.c ? ?| ? 54 ++++++++++++++++++++++++++++++++++++++++++++
?drivers/mmc/core/debugfs.c | ? ?5 ++++
?include/linux/mmc/host.h ? | ? ?3 ++
?lib/Kconfig.debug ? ? ? ? ?| ? 11 +++++++++
?4 files changed, 73 insertions(+), 0 deletions(-)

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index d2d7239..62a8cc7 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c

@@ -23,6 +23,8 @@

?#include <linux/log2.h>
?#include <linux/regulator/consumer.h>
?#include <linux/pm_runtime.h>
+#include <linux/fault-inject.h>
+#include <linux/random.h>

?#include <linux/mmc/card.h>
?#include <linux/mmc/host.h>

@@ -82,6 +84,56 @@ static void mmc_flush_scheduled_work(void)

? ? ? ?flush_workqueue(workqueue);
?}

+#ifdef CONFIG_FAIL_MMC_REQUEST
+
+static DECLARE_FAULT_ATTR(fail_mmc_request);
+
+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);
+
+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");
+}
+
+late_initcall(fail_mmc_request_debugfs);

+#endif /* CONFIG_FAIL_MMC_REQUEST */
+
+
?/**
?* ? ? mmc_request_done - finish processing an MMC request
?* ? ? @host: MMC host which completed request

@@ -108,6 +160,8 @@ 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",

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 59db6f2..0d0a48f 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h

@@ -301,6 +301,9 @@ 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..330fc70 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