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>

1 files changed, 25 insertions, 0 deletions

diff --git a/drivers/mmc/core/debugfs.c b/drivers/mmc/core/debugfs.c
index 998797ed67a6..5acd707699c9 100644
--- 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/fault-inject.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;
 }
 
+#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");
 
@@ -188,6 +206,13 @@ void mmc_add_host_debugfs(struct mmc_host *host)
                                 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;
 
 err_node: