[PATCH 0/4] Deprecate register_restart_handler()

[PATCH 0/4] Deprecate register_restart_handler()

[Andrew Davis]

Hello all,

Explanation is in patch #1.

The rest of this series is a set of representative examples of converting
away from the old API. They should be valid and can be taken by their
respective maintainers even if patch #1 doesn't find acceptance.

Thanks,
Andrew

Changes from RFC:
 - Add Reviewed-by tag
 - Rebase on v6.8-rc1 and drop taken patch

Andrew Davis (4):
  kernel/reboot: Deprecate register_restart_handler()
  drivers/soc/litex: Use devm_register_restart_handler()
  firmware: psci: Use register_sys_off_handler(SYS_OFF_MODE_RESTART)
  firmware: ti_sci: Use devm_register_restart_handler()

 drivers/firmware/psci/psci.c       | 10 ++--------
 drivers/firmware/ti_sci.c          | 14 +++++---------
 drivers/soc/litex/litex_soc_ctrl.c | 23 +++++------------------
 include/linux/reboot.h             |  8 ++++++--
 kernel/reboot.c                    |  3 +++
 5 files changed, 21 insertions(+), 37 deletions(-)

-- 
2.39.2

[PATCH 1/4] kernel/reboot: Deprecate register_restart_handler()

[Andrew Davis]

There are now two ways to add a handler to the restart_handler_list.
Two ways to do the same thing is bad design, so let's unify on using
the new method register_sys_off_handler() everywhere.

Reasons:
 * The other register_*_handler functions take a callback, this old
   API takes a notifier_block, which makes it confusing with the
   register_*_notifier class of functions.
 * register_sys_off_handler (new API) is a more unified API allowing for
   registering several system off types.
 * The new API has more helpers built around it now, including devm and
   platform helpers.
 * The new API manages the struct notifier_block for us, simplifying using
   code.

Mark register_restart_handler() as deprecated to try to warn off new users
while we finish converting the remaining existing users.

Signed-off-by: Andrew Davis <afd@ti.com>
---
 include/linux/reboot.h | 8 ++++++--
 kernel/reboot.c        | 3 +++
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/include/linux/reboot.h b/include/linux/reboot.h
index abcdde4df6979..186291e9bf3bb 100644
--- a/include/linux/reboot.h
+++ b/include/linux/reboot.h
@@ -46,8 +46,12 @@ extern int unregister_reboot_notifier(struct notifier_block *);
 
 extern int devm_register_reboot_notifier(struct device *, struct notifier_block *);
 
-extern int register_restart_handler(struct notifier_block *);
-extern int unregister_restart_handler(struct notifier_block *);
+/*
+ * This function is deprecated, use register_sys_off_handler(SYS_OFF_MODE_RESTART)
+ * or devm_register_restart_handler() instead.
+ */
+extern int __deprecated register_restart_handler(struct notifier_block *);
+extern int __deprecated unregister_restart_handler(struct notifier_block *);
 extern void do_kernel_restart(char *cmd);
 
 /*
diff --git a/kernel/reboot.c b/kernel/reboot.c
index 22c16e2564cca..38d6933fe892e 100644
--- a/kernel/reboot.c
+++ b/kernel/reboot.c
@@ -197,6 +197,9 @@ static ATOMIC_NOTIFIER_HEAD(restart_handler_list);
  *
  *	Currently always returns zero, as atomic_notifier_chain_register()
  *	always returns zero.
+ *
+ *	This function is deprecated, use register_sys_off_handler(SYS_OFF_MODE_RESTART)
+ *	or devm_register_restart_handler() instead.
  */
 int register_restart_handler(struct notifier_block *nb)
 {
-- 
2.39.2

[PATCH 2/4] drivers/soc/litex: Use devm_register_restart_handler()

[Andrew Davis]

Use device life-cycle managed register function to simplify probe error
path and eliminate need for explicit remove function.

Signed-off-by: Andrew Davis <afd@ti.com>
Reviewed-by: Gabriel Somlo <gsomlo@gmail.com>
---
 drivers/soc/litex/litex_soc_ctrl.c | 23 +++++------------------
 1 file changed, 5 insertions(+), 18 deletions(-)

diff --git a/drivers/soc/litex/litex_soc_ctrl.c b/drivers/soc/litex/litex_soc_ctrl.c
index 10813299aa106..7a0096d93c73d 100644
--- a/drivers/soc/litex/litex_soc_ctrl.c
+++ b/drivers/soc/litex/litex_soc_ctrl.c
@@ -69,14 +69,11 @@ static int litex_check_csr_access(void __iomem *reg_addr)
 
 struct litex_soc_ctrl_device {
 	void __iomem *base;
-	struct notifier_block reset_nb;
 };
 
-static int litex_reset_handler(struct notifier_block *this, unsigned long mode,
-			       void *cmd)
+static int litex_reset_handler(struct sys_off_data *data)
 {
-	struct litex_soc_ctrl_device *soc_ctrl_dev =
-		container_of(this, struct litex_soc_ctrl_device, reset_nb);
+	struct litex_soc_ctrl_device *soc_ctrl_dev = data->cb_data;
 
 	litex_write32(soc_ctrl_dev->base + RESET_REG_OFF, RESET_REG_VALUE);
 	return NOTIFY_DONE;
@@ -107,11 +104,9 @@ static int litex_soc_ctrl_probe(struct platform_device *pdev)
 	if (error)
 		return error;
 
-	platform_set_drvdata(pdev, soc_ctrl_dev);
-
-	soc_ctrl_dev->reset_nb.notifier_call = litex_reset_handler;
-	soc_ctrl_dev->reset_nb.priority = 128;
-	error = register_restart_handler(&soc_ctrl_dev->reset_nb);
+	error = devm_register_restart_handler(&pdev->dev,
+					      litex_reset_handler,
+					      soc_ctrl_dev);
 	if (error) {
 		dev_warn(&pdev->dev, "cannot register restart handler: %d\n",
 			 error);
@@ -120,20 +115,12 @@ static int litex_soc_ctrl_probe(struct platform_device *pdev)
 	return 0;
 }
 
-static void litex_soc_ctrl_remove(struct platform_device *pdev)
-{
-	struct litex_soc_ctrl_device *soc_ctrl_dev = platform_get_drvdata(pdev);
-
-	unregister_restart_handler(&soc_ctrl_dev->reset_nb);
-}
-
 static struct platform_driver litex_soc_ctrl_driver = {
 	.driver = {
 		.name = "litex-soc-controller",
 		.of_match_table = of_match_ptr(litex_soc_ctrl_of_match)
 	},
 	.probe = litex_soc_ctrl_probe,
-	.remove_new = litex_soc_ctrl_remove,
 };
 
 module_platform_driver(litex_soc_ctrl_driver);
-- 
2.39.2

[PATCH 3/4] firmware: psci: Use register_sys_off_handler(SYS_OFF_MODE_RESTART)

[Andrew Davis]

Function register_restart_handler() is deprecated. Using this new API
removes our need to keep and manage a struct notifier_block.

Signed-off-by: Andrew Davis <afd@ti.com>
---
 drivers/firmware/psci/psci.c | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/drivers/firmware/psci/psci.c b/drivers/firmware/psci/psci.c
index d9629ff878619..767a5af5384b4 100644
--- a/drivers/firmware/psci/psci.c
+++ b/drivers/firmware/psci/psci.c
@@ -305,8 +305,7 @@ static int get_set_conduit_method(const struct device_node *np)
 	return 0;
 }
 
-static int psci_sys_reset(struct notifier_block *nb, unsigned long action,
-			  void *data)
+static int psci_sys_reset(struct sys_off_data *data)
 {
 	if ((reboot_mode == REBOOT_WARM || reboot_mode == REBOOT_SOFT) &&
 	    psci_system_reset2_supported) {
@@ -323,11 +322,6 @@ static int psci_sys_reset(struct notifier_block *nb, unsigned long action,
 	return NOTIFY_DONE;
 }
 
-static struct notifier_block psci_sys_reset_nb = {
-	.notifier_call = psci_sys_reset,
-	.priority = 129,
-};
-
 static void psci_sys_poweroff(void)
 {
 	invoke_psci_fn(PSCI_0_2_FN_SYSTEM_OFF, 0, 0, 0);
@@ -623,7 +617,7 @@ static void __init psci_0_2_set_functions(void)
 		.migrate_info_type = psci_migrate_info_type,
 	};
 
-	register_restart_handler(&psci_sys_reset_nb);
+	register_sys_off_handler(SYS_OFF_MODE_RESTART, 129, psci_sys_reset, NULL);
 
 	pm_power_off = psci_sys_poweroff;
 }
-- 
2.39.2

[PATCH 4/4] firmware: ti_sci: Use devm_register_restart_handler()

[Andrew Davis]

Use device life-cycle managed register function to simplify probe.

Signed-off-by: Andrew Davis <afd@ti.com>
---
 drivers/firmware/ti_sci.c | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/drivers/firmware/ti_sci.c b/drivers/firmware/ti_sci.c
index 8b9a2556de16d..16501aa0b84cf 100644
--- a/drivers/firmware/ti_sci.c
+++ b/drivers/firmware/ti_sci.c
@@ -103,7 +103,6 @@ struct ti_sci_desc {
  */
 struct ti_sci_info {
 	struct device *dev;
-	struct notifier_block nb;
 	const struct ti_sci_desc *desc;
 	struct dentry *d;
 	void __iomem *debug_region;
@@ -122,7 +121,6 @@ struct ti_sci_info {
 
 #define cl_to_ti_sci_info(c)	container_of(c, struct ti_sci_info, cl)
 #define handle_to_ti_sci_info(h) container_of(h, struct ti_sci_info, handle)
-#define reboot_to_ti_sci_info(n) container_of(n, struct ti_sci_info, nb)
 
 #ifdef CONFIG_DEBUG_FS
 
@@ -3254,10 +3252,9 @@ devm_ti_sci_get_resource(const struct ti_sci_handle *handle, struct device *dev,
 }
 EXPORT_SYMBOL_GPL(devm_ti_sci_get_resource);
 
-static int tisci_reboot_handler(struct notifier_block *nb, unsigned long mode,
-				void *cmd)
+static int tisci_reboot_handler(struct sys_off_data *data)
 {
-	struct ti_sci_info *info = reboot_to_ti_sci_info(nb);
+	struct ti_sci_info *info = data->cb_data;
 	const struct ti_sci_handle *handle = &info->handle;
 
 	ti_sci_cmd_core_reboot(handle);
@@ -3400,10 +3397,9 @@ static int ti_sci_probe(struct platform_device *pdev)
 	ti_sci_setup_ops(info);
 
 	if (reboot) {
-		info->nb.notifier_call = tisci_reboot_handler;
-		info->nb.priority = 128;
-
-		ret = register_restart_handler(&info->nb);
+		ret = devm_register_restart_handler(dev,
+						    tisci_reboot_handler,
+						    info);
 		if (ret) {
 			dev_err(dev, "reboot registration fail(%d)\n", ret);
 			goto out;
-- 
2.39.2

Re: [PATCH 4/4] firmware: ti_sci: Use devm_register_restart_handler()

[Gabriel L. Somlo]

On Tue, Jan 23, 2024 at 10:44:43AM -0600, Andrew Davis wrote:
> Use device life-cycle managed register function to simplify probe.
> 
> Signed-off-by: Andrew Davis <afd@ti.com>

Reviewed-by: Gabriel Somlo <gsomlo@gmail.com>

> ---
>  drivers/firmware/ti_sci.c | 14 +++++---------
>  1 file changed, 5 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/firmware/ti_sci.c b/drivers/firmware/ti_sci.c
> index 8b9a2556de16d..16501aa0b84cf 100644
> --- a/drivers/firmware/ti_sci.c
> +++ b/drivers/firmware/ti_sci.c
> @@ -103,7 +103,6 @@ struct ti_sci_desc {
>   */
>  struct ti_sci_info {
>  	struct device *dev;
> -	struct notifier_block nb;
>  	const struct ti_sci_desc *desc;
>  	struct dentry *d;
>  	void __iomem *debug_region;
> @@ -122,7 +121,6 @@ struct ti_sci_info {
>  
>  #define cl_to_ti_sci_info(c)	container_of(c, struct ti_sci_info, cl)
>  #define handle_to_ti_sci_info(h) container_of(h, struct ti_sci_info, handle)
> -#define reboot_to_ti_sci_info(n) container_of(n, struct ti_sci_info, nb)
>  
>  #ifdef CONFIG_DEBUG_FS
>  
> @@ -3254,10 +3252,9 @@ devm_ti_sci_get_resource(const struct ti_sci_handle *handle, struct device *dev,
>  }
>  EXPORT_SYMBOL_GPL(devm_ti_sci_get_resource);
>  
> -static int tisci_reboot_handler(struct notifier_block *nb, unsigned long mode,
> -				void *cmd)
> +static int tisci_reboot_handler(struct sys_off_data *data)
>  {
> -	struct ti_sci_info *info = reboot_to_ti_sci_info(nb);
> +	struct ti_sci_info *info = data->cb_data;
>  	const struct ti_sci_handle *handle = &info->handle;
>  
>  	ti_sci_cmd_core_reboot(handle);
> @@ -3400,10 +3397,9 @@ static int ti_sci_probe(struct platform_device *pdev)
>  	ti_sci_setup_ops(info);
>  
>  	if (reboot) {
> -		info->nb.notifier_call = tisci_reboot_handler;
> -		info->nb.priority = 128;
> -
> -		ret = register_restart_handler(&info->nb);
> +		ret = devm_register_restart_handler(dev,
> +						    tisci_reboot_handler,
> +						    info);
>  		if (ret) {
>  			dev_err(dev, "reboot registration fail(%d)\n", ret);
>  			goto out;
> -- 
> 2.39.2
> 

Re: [PATCH 4/4] firmware: ti_sci: Use devm_register_restart_handler()

[kernel test robot]

Hi Andrew,

kernel test robot noticed the following build warnings:

[auto build test WARNING on lee-leds/for-leds-next]
[also build test WARNING on linus/master v6.8-rc1 next-20240125]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Andrew-Davis/kernel-reboot-Deprecate-register_restart_handler/20240124-005424
base:   https://git.kernel.org/pub/scm/linux/kernel/git/lee/leds.git for-leds-next
patch link:    https://lore.kernel.org/r/20240123164443.394642-5-afd%40ti.com
patch subject: [PATCH 4/4] firmware: ti_sci: Use devm_register_restart_handler()
config: arm64-defconfig (https://download.01.org/0day-ci/archive/20240129/202401291053.Bc9G6QTc-lkp@intel.com/config)
compiler: aarch64-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240129/202401291053.Bc9G6QTc-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202401291053.Bc9G6QTc-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/firmware/ti_sci.c:120: warning: Excess struct member 'nb' description in 'ti_sci_info'


vim +120 drivers/firmware/ti_sci.c

aa276781a64a5f Nishanth Menon 2016-10-18   85  
aa276781a64a5f Nishanth Menon 2016-10-18   86  /**
aa276781a64a5f Nishanth Menon 2016-10-18   87   * struct ti_sci_info - Structure representing a TI SCI instance
aa276781a64a5f Nishanth Menon 2016-10-18   88   * @dev:	Device pointer
aa276781a64a5f Nishanth Menon 2016-10-18   89   * @desc:	SoC description for this instance
912cffb4ed8612 Nishanth Menon 2016-10-18   90   * @nb:	Reboot Notifier block
aa276781a64a5f Nishanth Menon 2016-10-18   91   * @d:		Debugfs file entry
aa276781a64a5f Nishanth Menon 2016-10-18   92   * @debug_region: Memory region where the debug message are available
aa276781a64a5f Nishanth Menon 2016-10-18   93   * @debug_region_size: Debug region size
aa276781a64a5f Nishanth Menon 2016-10-18   94   * @debug_buffer: Buffer allocated to copy debug messages.
aa276781a64a5f Nishanth Menon 2016-10-18   95   * @handle:	Instance of TI SCI handle to send to clients.
aa276781a64a5f Nishanth Menon 2016-10-18   96   * @cl:		Mailbox Client
aa276781a64a5f Nishanth Menon 2016-10-18   97   * @chan_tx:	Transmit mailbox channel
aa276781a64a5f Nishanth Menon 2016-10-18   98   * @chan_rx:	Receive mailbox channel
aa276781a64a5f Nishanth Menon 2016-10-18   99   * @minfo:	Message info
aa276781a64a5f Nishanth Menon 2016-10-18  100   * @node:	list head
e69a35531589a2 Nishanth Menon 2018-08-28  101   * @host_id:	Host ID
aa276781a64a5f Nishanth Menon 2016-10-18  102   * @users:	Number of users of this instance
aa276781a64a5f Nishanth Menon 2016-10-18  103   */
aa276781a64a5f Nishanth Menon 2016-10-18  104  struct ti_sci_info {
aa276781a64a5f Nishanth Menon 2016-10-18  105  	struct device *dev;
aa276781a64a5f Nishanth Menon 2016-10-18  106  	const struct ti_sci_desc *desc;
aa276781a64a5f Nishanth Menon 2016-10-18  107  	struct dentry *d;
aa276781a64a5f Nishanth Menon 2016-10-18  108  	void __iomem *debug_region;
aa276781a64a5f Nishanth Menon 2016-10-18  109  	char *debug_buffer;
aa276781a64a5f Nishanth Menon 2016-10-18  110  	size_t debug_region_size;
aa276781a64a5f Nishanth Menon 2016-10-18  111  	struct ti_sci_handle handle;
aa276781a64a5f Nishanth Menon 2016-10-18  112  	struct mbox_client cl;
aa276781a64a5f Nishanth Menon 2016-10-18  113  	struct mbox_chan *chan_tx;
aa276781a64a5f Nishanth Menon 2016-10-18  114  	struct mbox_chan *chan_rx;
aa276781a64a5f Nishanth Menon 2016-10-18  115  	struct ti_sci_xfers_info minfo;
aa276781a64a5f Nishanth Menon 2016-10-18  116  	struct list_head node;
e69a35531589a2 Nishanth Menon 2018-08-28  117  	u8 host_id;
aa276781a64a5f Nishanth Menon 2016-10-18  118  	/* protected by ti_sci_list_mutex */
aa276781a64a5f Nishanth Menon 2016-10-18  119  	int users;
aa276781a64a5f Nishanth Menon 2016-10-18 @120  };
aa276781a64a5f Nishanth Menon 2016-10-18  121  

-- 
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