mmc: core: add random fault injection

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>
Acked-by: Akinobu Mita <akinobu.mita@gmail.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Chris Ball <cjb@laptop.org>

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index b27b940..eb3069d 100644 (file)
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -24,6 +24,8 @@
 #include <linux/regulator/consumer.h>
 #include <linux/pm_runtime.h>
 #include <linux/suspend.h>
 #include <linux/regulator/consumer.h>
 #include <linux/pm_runtime.h>
 #include <linux/suspend.h>

+#include <linux/fault-inject.h>
+#include <linux/random.h>

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


@@ -83,6 +85,43 @@ static void mmc_flush_scheduled_work(void)
        flush_workqueue(workqueue);
 }
 
        flush_workqueue(workqueue);
 }
 

+#ifdef CONFIG_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 ||
+           !should_fail(&host->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;
+}
+
+#else /* CONFIG_FAIL_MMC_REQUEST */
+
+static inline void mmc_should_fail_request(struct mmc_host *host,
+                                          struct mmc_request *mrq)
+{
+}
+
+#endif /* CONFIG_FAIL_MMC_REQUEST */
+

 /**
  *     mmc_request_done - finish processing an MMC request
  *     @host: MMC host which completed request
 /**
  *     mmc_request_done - finish processing an MMC request
  *     @host: MMC host which completed request


@@ -109,6 +148,8 @@ void mmc_request_done(struct mmc_host *host, struct mmc_request *mrq)
                cmd->error = 0;
                host->ops->request(host, mrq);
        } else {
                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",
                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..5acd707 100644 (file)
--- a/drivers/mmc/core/debugfs.c
+++ b/drivers/mmc/core/debugfs.c
@@ -12,6 +12,7 @@
 #include <linux/seq_file.h>
 #include <linux/slab.h>
 #include <linux/stat.h>
 #include <linux/seq_file.h>
 #include <linux/slab.h>
 #include <linux/stat.h>

+#include <linux/fault-inject.h>

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


@@ -158,6 +159,23 @@ static int mmc_clock_opt_set(void *data, u64 val)
        return 0;
 }
 
        return 0;
 }
 

+#ifdef CONFIG_FAIL_MMC_REQUEST
+
+static DECLARE_FAULT_ATTR(fail_mmc_request);
+
+#ifdef KERNEL
+/*
+ * 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);
+#endif /* KERNEL */
+#endif /* CONFIG_FAIL_MMC_REQUEST */
+

 DEFINE_SIMPLE_ATTRIBUTE(mmc_clock_fops, mmc_clock_opt_get, mmc_clock_opt_set,
        "%llu\n");
 
 DEFINE_SIMPLE_ATTRIBUTE(mmc_clock_fops, mmc_clock_opt_get, mmc_clock_opt_set,
        "%llu\n");
 


@@ -187,6 +205,13 @@ void mmc_add_host_debugfs(struct mmc_host *host)
        if (!debugfs_create_u32("clk_delay", (S_IRUSR | S_IWUSR),
                                root, &host->clk_delay))
                goto err_node;
        if (!debugfs_create_u32("clk_delay", (S_IRUSR | S_IWUSR),
                                root, &host->clk_delay))
                goto err_node;

+#endif
+#ifdef CONFIG_FAIL_MMC_REQUEST
+       host->fail_mmc_request = fail_mmc_request;
+       if (IS_ERR(fault_create_debugfs_attr("fail_mmc_request",
+                                            root,
+                                            &host->fail_mmc_request)))
+               goto err_node;

 #endif
        return;
 
 #endif
        return;
 

diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 1d09562..4c4bddf 100644 (file)
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -12,6 +12,7 @@
 
 #include <linux/leds.h>
 #include <linux/sched.h>
 
 #include <linux/leds.h>
 #include <linux/sched.h>

+#include <linux/fault-inject.h>

 
 #include <linux/mmc/core.h>
 #include <linux/mmc/pm.h>
 
 #include <linux/mmc/core.h>
 #include <linux/mmc/pm.h>


@@ -302,6 +303,10 @@ struct mmc_host {
 
        struct mmc_async_req    *areq;          /* active async req */
 
 
        struct mmc_async_req    *areq;          /* active async req */
 

+#ifdef CONFIG_FAIL_MMC_REQUEST
+       struct fault_attr       fail_mmc_request;
+#endif
+

        unsigned long           private[0] ____cacheline_aligned;
 };
 
        unsigned long           private[0] ____cacheline_aligned;
 };
 

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index c0cb9c4..1c7dbbf 100644 (file)
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1070,6 +1070,17 @@ config FAIL_IO_TIMEOUT
          Only works with drivers that use the generic timeout handling,
          for others it wont do anything.
 
          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
 config FAULT_INJECTION_DEBUG_FS
        bool "Debugfs entries for fault-injection capabilities"
        depends on FAULT_INJECTION && SYSFS && DEBUG_FS