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 per.forlin@linaro.org --- drivers/mmc/core/core.c | 54 ++++++++++++++++++++++++++++++++++++++++++++ drivers/mmc/core/debugfs.c | 5 ++++ include/linux/mmc/host.h | 4 ++- lib/Kconfig.debug | 11 +++++++++ 4 files changed, 73 insertions(+), 1 deletions(-)
diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c index e88dd36..db2be51 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); + +#else /* CONFIG_FAIL_MMC_REQUEST */ + +static 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 @@ -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 c056a3d..8b2b44b 100644 --- a/include/linux/mmc/host.h +++ b/include/linux/mmc/host.h @@ -251,7 +251,9 @@ struct mmc_host { #endif
struct dentry *debugfs_root; - +#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 + help + Provide fault-injection capability for MMC IO. + This will make the mmc core return data errors. This is + useful for testing the error handling in the mmc block device + and how the mmc host driver handle retries from + the block device. + config FAULT_INJECTION_DEBUG_FS bool "Debugfs entries for fault-injection capabilities" depends on FAULT_INJECTION && SYSFS && DEBUG_FS