On Tue, Aug 9, 2011 at 2:07 PM, Per Forlin per.forlin@linaro.org wrote:
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.
Good idea!
diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c index 89bdeae..a4996b0 100644 --- a/drivers/mmc/core/core.c +++ b/drivers/mmc/core/core.c @@ -25,6 +25,11 @@ #include <linux/pm_runtime.h> #include <linux/suspend.h>
+#ifdef CONFIG_FAIL_MMC_REQUEST +#include <linux/fault-inject.h> +#include <linux/random.h> +#endif
You don't need to #ifdef around the #include <> stuff, and if you do, something is wrong with those headers. It's just a bunch of defines that aren't used in some circumstances. Stack them with the others, simply, just #ifdef the code below.
@@ -83,6 +88,43 @@ static void mmc_flush_scheduled_work(void) 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 void mmc_should_fail_request(struct mmc_host *host,
- struct mmc_request *mrq)
Should be "static inline" so we know it will be folded in and nullified by the compiler, lots of kernel code use that pattern.
diff --git a/drivers/mmc/core/debugfs.c b/drivers/mmc/core/debugfs.c index f573753..189581d 100644 --- a/drivers/mmc/core/debugfs.c +++ b/drivers/mmc/core/debugfs.c @@ -13,6 +13,9 @@ #include <linux/seq_file.h> #include <linux/slab.h> #include <linux/stat.h> +#ifdef CONFIG_FAIL_MMC_REQUEST +#include <linux/fault-inject.h> +#endif
No #ifdef:ing...
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h index 0f83858..ee472fe 100644 --- a/include/linux/mmc/host.h +++ b/include/linux/mmc/host.h @@ -12,6 +12,9 @@
#include <linux/leds.h> #include <linux/sched.h> +#ifdef CONFIG_FAIL_MMC_REQUEST +#include <linux/fault-inject.h> +#endif
Neither here...
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 47879c7..ebff0c9 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug
I'm contemplating if we should create drivers/mmc/Kconfig.debug and stash this in there instead, i.e. also move out MMC_DEBUG from drivers/mmc/Kconfig and add to that?
It seems more apropriate to select this from the MMC subsystem. However the core of fault injection is in lib/
So maybe a simple:
config FAIL_MMC_REQUEST bool select FAULT_INJECTION
That can then be selected by a debug option in the MMC subsystem? I fear it may be hard to find this otherwise...
(NB: I have very little clue how the Kconfig.debug files get sourced into the Kbuild so I might be misguided...)
@@ -1090,6 +1090,17 @@ 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
Isn't:
depends on MMC select FAULT_INJECTION
Simpler to use? Now you have to select fault injection first to even see this option right?
Apart from this it looks fine.
Thanks, Linus Walleij