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Subject: Re: [PATCH v8 2/4] power: reset: add reboot mode driver
To: Andy Yan <andy.yan@rock-chips.com>, robh+dt@kernel.org, heiko@sntech.de,
        sre@kernel.org
References: <1461567051-21734-1-git-send-email-andy.yan@rock-chips.com>
 <1461567336-21834-1-git-send-email-andy.yan@rock-chips.com>
 <571DF49F.6000706@samsung.com> <571DFFB0.4010409@rock-chips.com>
Cc: john.stultz@linaro.org, arnd@arndb.de, pawel.moll@arm.com,
        mark.rutland@arm.com, ijc+devicetree@hellion.org.uk,
        galak@codeaurora.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, dbaryshkov@gmail.com,
        dwmw2@infradead.org, alexandre.belloni@free-electrons.com,
        moritz.fischer@ettus.com, f.fainelli@gmail.com,
        linux-pm@vger.kernel.org
From: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Message-id: <571E122B.2070401@samsung.com>
Date: Mon, 25 Apr 2016 14:48:43 +0200
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On 04/25/2016 01:29 PM, Andy Yan wrote:
> Hi Krzysztof:
> 
> On 2016年04月25日 18:42, Krzysztof Kozlowski wrote:
>> On 04/25/2016 08:55 AM, Andy Yan wrote:
>>> This driver parses the reboot commands like "reboot bootloader"
>>> and "reboot recovery" to get a boot mode described in the
>>> device tree , then call the write interfae to store the boot
>>> mode in some place like special register or sram, which can
>>> be read by the bootloader after system reboot, then the bootloader
>>> can take different action according to the mode stored.
>>>
>>> This is commonly used on Android based devices, in order to
>>> reboot the device into fastboot or recovery mode.
>>>
>>> Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
>>> Reviewed-by: Moritz Fischer <moritz.fischer@ettus.com>
>>> Tested-by: John Stultz <john.stultz@linaro.org>
>>> Acked-by: John Stultz <john.stultz@linaro.org>
>>> Signed-off-by: Andy Yan <andy.yan@rock-chips.com>
>>>
>>> ---
>>>
>>> Changes in v8:
>>> - do some cleanup when driver ubind
>>>
>>> Changes in v7:
>>> - address some suggestions from Krzysztof, make syscon-reboot-mode
>>> driver data self-contained.
>>>
>>> Changes in v6: None
>>> Changes in v5:
>>> - use two blank space under help in Kconfig
>>> - use unsigned int instead of int for member magic in struct mode_info
>>>
>>> Changes in v4:
>>> - make this driver depends on OF to avoid kbuild test error
>>>
>>> Changes in v3:
>>> - scan multi properities
>>> - add mask value for some platform which only use some bits of the
>>> register
>>>    to store boot mode magic value
>>>
>>> Changes in v2:
>>> - move to dir drivers/power/reset/
>>> - make syscon-reboot-mode a generic driver
>>>
>>> Changes in v1:
>>> - fix the embarrassed compile warning
>>> - correct the maskrom magic number
>>> - check for the normal reboot
>>>
>>>   drivers/power/reset/Kconfig              |  13 ++++
>>>   drivers/power/reset/Makefile             |   2 +
>>>   drivers/power/reset/reboot-mode.c        | 118
>>> +++++++++++++++++++++++++++++++
>>>   drivers/power/reset/reboot-mode.h        |  14 ++++
>>>   drivers/power/reset/syscon-reboot-mode.c |  99
>>> ++++++++++++++++++++++++++
>>>   5 files changed, 246 insertions(+)
>>>   create mode 100644 drivers/power/reset/reboot-mode.c
>>>   create mode 100644 drivers/power/reset/reboot-mode.h
>>>   create mode 100644 drivers/power/reset/syscon-reboot-mode.c
>>>
>>> diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig
>>> index 1131cf7..cf50630 100644
>>> --- a/drivers/power/reset/Kconfig
>>> +++ b/drivers/power/reset/Kconfig
>>> @@ -173,5 +173,18 @@ config POWER_RESET_ZX
>>>       help
>>>         Reboot support for ZTE SoCs.
>>>   +config REBOOT_MODE
>>> +    tristate
>>> +
>>> +config SYSCON_REBOOT_MODE
>>> +    bool "Generic SYSCON regmap reboot mode driver"
>>> +    depends on OF
>>> +    select REBOOT_MODE
>>> +    help
>>> +      Say y here will enable reboot mode driver. This will
>>> +      get reboot mode arguments and store it in SYSCON mapped
>>> +      register, then the bootloader can read it to take different
>>> +      action according to the mode.
>>> +
>>>   endif
>>>   diff --git a/drivers/power/reset/Makefile
>>> b/drivers/power/reset/Makefile
>>> index 096fa67..a63865b 100644
>>> --- a/drivers/power/reset/Makefile
>>> +++ b/drivers/power/reset/Makefile
>>> @@ -20,3 +20,5 @@ obj-$(CONFIG_POWER_RESET_SYSCON) += syscon-reboot.o
>>>   obj-$(CONFIG_POWER_RESET_SYSCON_POWEROFF) += syscon-poweroff.o
>>>   obj-$(CONFIG_POWER_RESET_RMOBILE) += rmobile-reset.o
>>>   obj-$(CONFIG_POWER_RESET_ZX) += zx-reboot.o
>>> +obj-$(CONFIG_REBOOT_MODE) += reboot-mode.o
>>> +obj-$(CONFIG_SYSCON_REBOOT_MODE) += syscon-reboot-mode.o
>>> diff --git a/drivers/power/reset/reboot-mode.c
>>> b/drivers/power/reset/reboot-mode.c
>>> new file mode 100644
>>> index 0000000..cdc4d72
>>> --- /dev/null
>>> +++ b/drivers/power/reset/reboot-mode.c
>>> @@ -0,0 +1,118 @@
>>> +/*
>>> + * Copyright (c) 2016, Fuzhou Rockchip Electronics Co., Ltd
>>> + *
>>> + * This program is free software; you can redistribute it and/or modify
>>> + * it under the terms of the GNU General Public License as published by
>>> + * the Free Software Foundation; either version 2 of the License, or
>>> + * (at your option) any later version.
>>> + */
>>> +
>>> +#include <linux/device.h>
>>> +#include <linux/init.h>
>>> +#include <linux/kernel.h>
>>> +#include <linux/module.h>
>>> +#include <linux/of.h>
>>> +#include <linux/reboot.h>
>>> +#include "reboot-mode.h"
>>> +
>>> +#define PREFIX "mode-"
>>> +
>>> +struct mode_info {
>>> +    const char *mode;
>>> +    unsigned int magic;
>>> +    struct list_head list;
>>> +};
>>> +
>>> +static int get_reboot_mode_magic(struct reboot_mode_driver *reboot,
>>> +                 const char *cmd)
>>> +{
>>> +    const char *normal = "normal";
>>> +    int magic = 0;
>>> +    struct mode_info *info;
>>> +
>>> +    if (!cmd)
>>> +        cmd = normal;
>>> +
>>> +    list_for_each_entry(info, &reboot->head, list) {
>>> +        if (!strcmp(info->mode, cmd)) {
>>> +            magic = info->magic;
>>> +            break;
>>> +        }
>>> +    }
>>> +
>>> +    return magic;
>>> +}
>>> +
>>> +static int reboot_mode_notify(struct notifier_block *this,
>>> +                  unsigned long mode, void *cmd)
>>> +{
>>> +    struct reboot_mode_driver *reboot;
>>> +    int magic;
>>> +
>>> +    reboot = container_of(this, struct reboot_mode_driver,
>>> reboot_notifier);
>>> +    magic = get_reboot_mode_magic(reboot, cmd);
>>> +    if (magic)
>>> +        reboot->write(reboot, magic);
>>> +
>>> +    return NOTIFY_DONE;
>>> +}
>>> +
>>> +int reboot_mode_register(struct reboot_mode_driver *reboot)
>>> +{
>>> +    struct mode_info *info;
>>> +    struct property *prop;
>>> +    struct device_node *np = reboot->dev->of_node;
>>> +    size_t len = strlen(PREFIX);
>>> +    int ret;
>>> +
>>> +    INIT_LIST_HEAD(&reboot->head);
>>> +
>>> +    for_each_property_of_node(np, prop) {
>>> +        if (len > strlen(prop->name) || strncmp(prop->name, PREFIX,
>>> len))
>>> +            continue;
>>> +
>>> +        info = devm_kzalloc(reboot->dev, sizeof(*info), GFP_KERNEL);
>>> +        if (!info) {
>>> +            ret = -ENOMEM;
>>> +            goto error;
>>> +        }
>>> +
>>> +        info->mode = kstrdup_const(prop->name + len, GFP_KERNEL);
>>> +        if (of_property_read_u32(np, prop->name, &info->magic)) {
>>> +            dev_err(reboot->dev, "reboot mode %s without magic
>>> number\n",
>>> +                info->mode);
>>> +            devm_kfree(reboot->dev, info);
>> kfree_const(). The duplicated string won't be added to the list so it
>> won't be freed in error path or in unregister().
> 
>    Each mode has a mode_info,  if one of them gets an error whith
> devm_kzalloc, they other mode_info add to the list before should be freed.

Please, write it again. I don't understand.

You are allocating 'info'. Then you are const-allocating 'info->mode'.
In this error path you are freeing 'info'. Where is the kfree_const()
for 'info->mode'?

>>
>>> +            continue;
>>> +        }
>>> +        list_add_tail(&info->list, &reboot->head);
>>> +    }
>>> +
>>> +    reboot->reboot_notifier.notifier_call = reboot_mode_notify;
>>> +    ret = register_reboot_notifier(&reboot->reboot_notifier);
>>> +    if (ret)
>>> +        dev_err(reboot->dev, "can't register reboot notifier\n");
>> I don't understand your error paths. In previous patches they were
>> buggy... they still look buggy, I think. It's 8th iteration and such
>> basic things are still present.
>>
>> If this is an error then shouldn't everything be cleaned up? You are
>> returning error code thus the reboot_mode_register() caller will fail.
>> This means the probe will fail. So you need to clean up - go to error?
> 
>     If this is an error, I think only the duplicated string should be
> clean up,because other resources allocated by devm. If there is
> something else, please let me know.

Just goto error...

Best regards,
Krzysztof