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Message-ID: <4E261B7F.8020002@linux.intel.com>
Date: Tue, 19 Jul 2011 17:04:15 -0700
From: J Freyensee <james_p_freyensee@...ux.intel.com>
To: Per Forlin <per.forlin@...aro.org>
CC: linaro-dev@...ts.linaro.org,
Nicolas Pitre <nicolas.pitre@...aro.org>,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
linux-mmc@...r.kernel.org, linux-doc@...r.kernel.org,
Venkatraman S <svenkatr@...com>,
Linus Walleij <linus.walleij@...aro.org>,
Kyungmin Park <kyungmin.park@...sung.com>,
Arnd Bergmann <arnd@...db.de>,
Sourav Poddar <sourav.poddar@...com>,
Chris Ball <cjb@...top.org>,
Akinobu Mita <akinobu.mita@...il.com>,
Randy Dunlap <rdunlap@...otime.net>
Subject: Re: [PATCH v2 2/3] mmc: core: add random fault injection
On 07/19/2011 02:31 PM, Per Forlin 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.
>
> Signed-off-by: Per Forlin<per.forlin@...aro.org>
> ---
> drivers/mmc/core/core.c | 58 ++++++++++++++++++++++++++++++++++++++++++++
> drivers/mmc/core/debugfs.c | 5 ++++
> include/linux/mmc/host.h | 3 ++
> lib/Kconfig.debug | 11 ++++++++
> 4 files changed, 77 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> index ab36c7b..3f822b4 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>
>
As a suggestion, would you want to also use '#ifdef
CONFIG_FAIL_MMC_REQUEST' for fault-inject.h and random.h? If they are
not used in a non-debug linux kernel configuration, could this possibly
cause a little extra code bloat if they are a part of a production Linux
kernel compile/configuration?
> #include<linux/mmc/card.h>
> #include<linux/mmc/host.h>
> @@ -82,6 +84,58 @@ 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)
Function comment header somewhere (here or the .h file?)
> +{
> + 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)
> +{
Function comment header somewhere (here or the .h file)?
> + struct mmc_command *cmd = mrq->cmd;
> + struct mmc_data *data = mrq->data;
> + static const int data_errors[] = {
> + -ETIMEDOUT,
> + -EILSEQ,
> + -EIO,
> + };
> +
> + if (!data)
> + return;
> +
Should 'if (!cmd)' also be checked or is this guaranteed to always have
a valid value for this function (and if there are certain commands in
'struct mmc_command *cmd = mrq->cmd' that will not work with this
function then that is something that should be documented in the
function comment header)?
> + 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");
> +}
> +
> +#else /* CONFIG_FAIL_MMC_REQUEST */
> +
> +static void mmc_should_fail_request(struct mmc_host *host,
> + struct mmc_request *mrq)
> +{
> +}
> +
> +static int __init fail_mmc_request_debugfs(void)
> +{
> + return 0;
> +}
> +#endif /* CONFIG_FAIL_MMC_REQUEST */
> +
> +
> /**
> * mmc_request_done - finish processing an MMC request
> * @host: MMC host which completed request
> @@ -108,6 +162,8 @@ 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",
> @@ -2064,6 +2120,8 @@ static int __init mmc_init(void)
> if (ret)
> goto unregister_host_class;
>
> + fail_mmc_request_debugfs();
> +
> return 0;
>
> unregister_host_class:
> 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 771455f..250b46d 100644
> --- a/include/linux/mmc/host.h
> +++ b/include/linux/mmc/host.h
> @@ -303,6 +303,9 @@ 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..c2d1423 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&& 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
--
J (James/Jay) Freyensee
Storage Technology Group
Intel Corporation
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