From: Dmitry Osipenko <digetx@gmail•com>
To: "Michał Mirosław" <mirq-linux@rere•qmqm.pl>
Cc: Ulf Hansson <ulf.hansson@linaro•org>,
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Subject: Re: [PATCH v4 08/25] kernel: Add combined power-off+restart handler call chain API
Date: Mon, 29 Nov 2021 14:52:25 +0300 [thread overview]
Message-ID: <33d1dfa7-e90e-d174-7375-836c15e7f818@gmail.com> (raw)
In-Reply-To: <YaQgiLw03lPyvuhr@qmqm.qmqm.pl>
29.11.2021 03:36, Michał Mirosław пишет:
> On Mon, Nov 29, 2021 at 12:53:51AM +0300, Dmitry Osipenko wrote:
>> 29.11.2021 00:17, Michał Mirosław пишет:
>>>> I'm having trouble with parsing this comment. Could you please try to
>>>> rephrase it? I don't see how you could check whether power-off handler
>>>> is available if you'll mix all handlers together.
>>> If notify_call_chain() would be fixed to return NOTIFY_OK if any call
>>> returned NOTIFY_OK, then this would be a clear way to gather the
>>> answer if any of the handlers will attempt the final action (reboot or
>>> power off).
>> Could you please show a code snippet that implements your suggestion?
>
> A rough idea is this:
>
> static int notifier_call_chain(struct notifier_block **nl,
> unsigned long val, void *v,
> int nr_to_call, int *nr_calls)
> {
> - int ret = NOTIFY_DONE;
> + int ret, result = NOTIFY_DONE;
> struct notifier_block *nb, *next_nb;
>
> nb = rcu_dereference_raw(*nl);
>
> while (nb && nr_to_call) {
> ...
> ret = nb->notifier_call(nb, val, v);
> +
> + /* Assuming NOTIFY_STOP-carrying return is always greater than non-stopping one. */
> + if (result < ret)
> + result = ret;
> ...
> }
> - return ret;
> + return result;
> }
>
> Then:
>
> bool prepare_reboot()
> {
> int ret = xx_notifier_call_chain(&shutdown_notifier, PREPARE_REBOOT, ...);
> return ret == NOTIFY_OK;
> }
>
> And the return value would signify whether the reboot will be attempted
> when calling the chain for the REBOOT action. (Analogously for powering off.)
If you started to execute call chain, then you began the power-off /
restart sequence, this is a point of no return. Sorry, I still don't
understand what you're trying to achieve.
The approach of having separate call chains is simple and intuitive, I
don't see reasons to change it.
next prev parent reply other threads:[~2021-11-29 12:30 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-26 18:00 [PATCH v4 00/25] Introduce power-off+restart call chain API Dmitry Osipenko
2021-11-26 18:00 ` [PATCH v4 01/25] notifier: Remove extern annotation from function prototypes Dmitry Osipenko
2021-11-26 18:00 ` [PATCH v4 02/25] notifier: Add blocking_notifier_call_chain_is_empty() Dmitry Osipenko
2021-12-10 18:14 ` Rafael J. Wysocki
2021-12-10 18:19 ` Dmitry Osipenko
2021-11-26 18:00 ` [PATCH v4 03/25] notifier: Add atomic/blocking_notifier_has_unique_priority() Dmitry Osipenko
2021-12-10 18:19 ` Rafael J. Wysocki
2021-12-10 18:52 ` Dmitry Osipenko
2021-12-10 19:05 ` Rafael J. Wysocki
2021-12-10 19:33 ` Dmitry Osipenko
2021-12-10 20:16 ` Dmitry Osipenko
2021-11-26 18:00 ` [PATCH v4 04/25] reboot: Correct typo in a comment Dmitry Osipenko
2021-12-10 18:21 ` Rafael J. Wysocki
2021-11-26 18:00 ` [PATCH v4 05/25] reboot: Warn if restart handler has duplicated priority Dmitry Osipenko
2021-11-28 0:28 ` Michał Mirosław
2021-11-28 21:06 ` Dmitry Osipenko
2021-11-29 0:26 ` Michał Mirosław
2021-11-29 11:34 ` Dmitry Osipenko
2021-12-10 18:27 ` Rafael J. Wysocki
2021-12-10 19:04 ` Dmitry Osipenko
2021-12-10 19:14 ` Rafael J. Wysocki
2021-12-10 19:42 ` Dmitry Osipenko
2021-12-10 19:44 ` Dmitry Osipenko
2021-12-10 19:49 ` Dmitry Osipenko
2021-12-13 9:23 ` Geert Uytterhoeven
2021-11-26 18:00 ` [PATCH v4 06/25] reboot: Warn if unregister_restart_handler() fails Dmitry Osipenko
2021-12-10 18:32 ` Rafael J. Wysocki
2021-12-10 18:54 ` Dmitry Osipenko
2021-12-10 19:08 ` Rafael J. Wysocki
2021-12-10 19:38 ` Dmitry Osipenko
2021-11-26 18:00 ` [PATCH v4 07/25] reboot: Remove extern annotation from function prototypes Dmitry Osipenko
2021-12-10 18:09 ` Rafael J. Wysocki
2021-12-10 18:15 ` Dmitry Osipenko
2021-12-10 18:35 ` Rafael J. Wysocki
2021-12-10 18:56 ` Dmitry Osipenko
2021-11-26 18:00 ` [PATCH v4 08/25] kernel: Add combined power-off+restart handler call chain API Dmitry Osipenko
2021-11-28 0:43 ` Michał Mirosław
2021-11-28 21:04 ` Dmitry Osipenko
2021-11-28 21:17 ` Michał Mirosław
2021-11-28 21:53 ` Dmitry Osipenko
2021-11-29 0:36 ` Michał Mirosław
2021-11-29 11:52 ` Dmitry Osipenko [this message]
2021-11-26 18:00 ` [PATCH v4 09/25] ARM: Use do_kernel_power_off() Dmitry Osipenko
2021-11-26 18:00 ` [PATCH v4 10/25] csky: " Dmitry Osipenko
2021-11-26 18:00 ` [PATCH v4 11/25] riscv: " Dmitry Osipenko
2021-11-26 18:00 ` [PATCH v4 12/25] arm64: " Dmitry Osipenko
2021-11-26 18:00 ` [PATCH v4 13/25] parisc: " Dmitry Osipenko
2021-11-26 18:00 ` [PATCH v4 14/25] xen/x86: " Dmitry Osipenko
2021-11-26 18:00 ` [PATCH v4 15/25] powerpc: " Dmitry Osipenko
2021-11-26 18:00 ` [PATCH v4 16/25] m68k: Switch to new sys-off handler API Dmitry Osipenko
2021-11-26 18:00 ` [PATCH v4 17/25] sh: Use do_kernel_power_off() Dmitry Osipenko
2021-11-26 18:00 ` [PATCH v4 18/25] x86: " Dmitry Osipenko
2021-11-28 1:15 ` Michał Mirosław
2021-11-28 21:06 ` Dmitry Osipenko
2021-11-26 18:00 ` [PATCH v4 19/25] ia64: " Dmitry Osipenko
2021-11-26 18:00 ` [PATCH v4 20/25] mips: " Dmitry Osipenko
2021-11-26 18:00 ` [PATCH v4 21/25] nds32: " Dmitry Osipenko
2021-11-26 18:00 ` [PATCH v4 22/25] memory: emif: Use kernel_can_power_off() Dmitry Osipenko
2021-11-28 1:23 ` Michał Mirosław
2021-11-28 21:04 ` Dmitry Osipenko
2021-11-26 18:00 ` [PATCH v4 23/25] ACPI: power: Switch to sys-off handler API Dmitry Osipenko
2021-11-26 18:01 ` [PATCH v4 24/25] regulator: pfuze100: Use devm_register_sys_off_handler() Dmitry Osipenko
2021-11-26 18:01 ` [PATCH v4 25/25] reboot: Remove pm_power_off_prepare() Dmitry Osipenko
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