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Date: Wed, 18 Dec 2019 12:16:28 -0800
From: nguyenb@...eaurora.org
To: Greg KH <gregkh@...uxfoundation.org>
Cc: ulf.hansson@...aro.org, robh+dt@...nel.org,
linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
asutoshd@...eaurora.org, cang@...eaurora.org,
"Bao D. Nguyen" <nguyenb@...cinc.com>
Subject: Re: [<PATCH v1> 9/9] mmc: sd: Fix trivial SD card issues
On 2019-12-18 00:29, Greg KH wrote:
> On Mon, Dec 16, 2019 at 06:50:42PM -0800, Bao D. Nguyen wrote:
>> From: "Bao D. Nguyen" <nguyenb@...cinc.com>
>>
>> Fix various trivial SD card issues.
>
> There are a number of real bugfixes in here, please split these out and
> put them at the beginning of the series so that they can be backported
> to the stable kernel tree. Specifics below:
>
>>
>> Signed-off-by: Bao D. Nguyen <nguyenb@...eaurora.org>
>> ---
>> drivers/mmc/core/block.c | 4 ++--
>> drivers/mmc/core/bus.c | 13 +++++++++++++
>> drivers/mmc/core/core.c | 13 ++++++++-----
>> drivers/mmc/core/sd.c | 9 ++++++---
>> 4 files changed, 29 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
>> index 95b41c0..200882d 100644
>> --- a/drivers/mmc/core/block.c
>> +++ b/drivers/mmc/core/block.c
>> @@ -653,13 +653,13 @@ static int mmc_blk_ioctl_cmd(struct mmc_blk_data
>> *md,
>> struct request *req;
>>
>> idata = mmc_blk_ioctl_copy_from_user(ic_ptr);
>> - if (IS_ERR(idata))
>> + if (IS_ERR_OR_NULL(idata))
>
> How can this function ever return NULL?
>
>> return PTR_ERR(idata);
>
> If NULL was returned, are you sure you can return 0 here? That implies
> that all went well, when obviously it did not.
>
> But again, I do not see how mmc_blk_ioctl_copy_from_user() can return
> NULL, do you?
>
>> /* This will be NULL on non-RPMB ioctl():s */
>> idata->rpmb = rpmb;
>>
>> card = md->queue.card;
>> - if (IS_ERR(card)) {
>> + if (IS_ERR_OR_NULL(card)) {
>
> How can card be NULL?
>
>> err = PTR_ERR(card);
>
> Again, returning "success" is ok? Are you sure?
>
>> goto cmd_done;
>> }
>> diff --git a/drivers/mmc/core/bus.c b/drivers/mmc/core/bus.c
>> index 74de3f2..fb17d21 100644
>> --- a/drivers/mmc/core/bus.c
>> +++ b/drivers/mmc/core/bus.c
>> @@ -131,6 +131,16 @@ static void mmc_bus_shutdown(struct device *dev)
>> struct mmc_host *host = card->host;
>> int ret;
>>
>> + if (!drv) {
>> + pr_debug("%s: %s: drv is NULL\n", dev_name(dev), __func__);
>
> How can this ever happen?
>
> And never use pr_* calls in a driver, you have a valid device, use
> dev_dbg() and friends.
>
>> + return;
>> + }
>> +
>> + if (!card) {
>> + pr_debug("%s: %s: card is NULL\n", dev_name(dev), __func__);
>
> Same here, how can this ever happen?
>
>> + return;
>> + }
>> +
>> if (dev->driver && drv->shutdown)
>> drv->shutdown(card);
>>
>> @@ -247,12 +257,15 @@ void mmc_unregister_driver(struct mmc_driver
>> *drv)
>> static void mmc_release_card(struct device *dev)
>> {
>> struct mmc_card *card = mmc_dev_to_card(dev);
>> + struct mmc_host *host = card->host;
>>
>> sdio_free_common_cis(card);
>>
>> kfree(card->info);
>>
>> kfree(card);
>> + if (host)
>> + host->card = NULL;
>
> Why are you setting this to null? Does this solve some race condition
> that you are then catching in the shutdown callback? If so, this
> should
> be broken out as a separate bugfix and put earlier in the series as
> that
> should go to all stable kernels, right?
>
>> }
>>
>> /*
>> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
>> index 38b0cec..13d496e 100644
>> --- a/drivers/mmc/core/core.c
>> +++ b/drivers/mmc/core/core.c
>> @@ -399,7 +399,7 @@ void mmc_wait_for_req_done(struct mmc_host *host,
>> struct mmc_request *mrq)
>> struct mmc_command *cmd;
>>
>> while (1) {
>> - wait_for_completion(&mrq->completion);
>> + wait_for_completion_io(&mrq->completion);
>
> Why this change? That seems like a big one. Why is this not a
> separate
> patch?
>
>>
>> cmd = mrq->cmd;
>>
>> @@ -666,6 +666,10 @@ void mmc_set_data_timeout(struct mmc_data *data,
>> const struct mmc_card *card)
>> {
>> unsigned int mult;
>>
>> + if (!card) {
>> + WARN_ON(1);
>
> And you just crashed systems that run with panic-on-warn :(
>
> How can this ever happen? If it is a real issue, catch it, log it, and
> then move on, don't splat the kernel log with a full traceback and
> reboot machines :(
>
>> + return;
>> + }
>> /*
>> * SDIO cards only define an upper 1 s limit on access.
>> */
>> @@ -2341,17 +2345,16 @@ void mmc_rescan(struct work_struct *work)
>>
>> void mmc_start_host(struct mmc_host *host)
>> {
>> + mmc_claim_host(host);
>
> What? This is a totally separate change, plaese break this out and
> describe what you are fixing here. Again, should be a bugfix for
> earlier in the series.
>
>> host->f_init = max(freqs[0], host->f_min);
>> host->rescan_disable = 0;
>> host->ios.power_mode = MMC_POWER_UNDEFINED;
>>
>> - if (!(host->caps2 & MMC_CAP2_NO_PRESCAN_POWERUP)) {
>> - mmc_claim_host(host);
>> + if (!(host->caps2 & MMC_CAP2_NO_PRESCAN_POWERUP))
>> mmc_power_up(host, host->ocr_avail);
>> - mmc_release_host(host);
>> - }
>>
>> mmc_gpiod_request_cd_irq(host);
>> + mmc_release_host(host);
>
> And are you sure the reference counting is correct here? Before this
> patch, you dropped the reference above, now you are matching it.
> Either
> this is wrong, or the original code is wrong. Either way, you need to
> describe it much better please.
>
>> _mmc_detect_change(host, 0, false);
>> }
>>
>> diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
>> index 5938caf..e163f0e 100644
>> --- a/drivers/mmc/core/sd.c
>> +++ b/drivers/mmc/core/sd.c
>> @@ -989,6 +989,7 @@ static int mmc_sd_init_card(struct mmc_host *host,
>> u32 ocr,
>> err = mmc_send_relative_addr(host, &card->rca);
>> if (err)
>> goto free_card;
>> + host->card = card;
>
> Why?
>
>> }
>>
>> if (!oldcard) {
>> @@ -1090,13 +1091,13 @@ static int mmc_sd_init_card(struct mmc_host
>> *host, u32 ocr,
>> goto free_card;
>> }
>> done:
>> - host->card = card;
>> return 0;
>>
>> free_card:
>> - if (!oldcard)
>> + if (!oldcard) {
>> + host->card = NULL;
>
> Again, why?
>
>> mmc_remove_card(card);
>> -
>> + }
>> return err;
>> }
>>
>> @@ -1106,7 +1107,9 @@ static int mmc_sd_init_card(struct mmc_host
>> *host, u32 ocr,
>> static void mmc_sd_remove(struct mmc_host *host)
>> {
>> mmc_remove_card(host->card);
>> + mmc_claim_host(host);
>> host->card = NULL;
>> + mmc_release_host(host);
>
> Huh? What is this "fixing"?
>
> Again, please break all of these out into logical bugfixes and describe
> what you are doing.
>
> thanks,
>
> greg k-h
Thank you for providing the feedback. There are a lot of good feedback
and it will take me a bit of time to review them and make changes
properly.
Regards,
Bao
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