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Date: Mon, 7 Nov 2022 01:28:50 +0300 From: Dmitry Osipenko <dmitry.osipenko@...labora.com> To: Samuel Holland <samuel@...lland.org>, "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>, Mark Rutland <mark.rutland@....com>, Lorenzo Pieralisi <lpieralisi@...nel.org> Cc: linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org Subject: Re: [PATCH 1/2] kernel/reboot: Use the static sys-off handler for any priority On 11/6/22 00:48, Samuel Holland wrote: > commit 587b9bfe0668 ("kernel/reboot: Use static handler for > register_platform_power_off()") addded a statically-allocated handler > so register_sys_off_handler() could be called before the slab allocator > is available. > > That behavior was limited to the SYS_OFF_PRIO_PLATFORM priority. > However, it is also required for handlers such as PSCI on ARM, which > needs to be registered at SYS_OFF_PRIO_FIRMWARE. Currently, this call > stack crashes: > > start_kernel() > setup_arch() > psci_dt_init() > psci_0_2_init() > register_sys_off_handler() > kmem_cache_alloc() > > Generalize the code to use the statically-allocated handler for the > first registration, regardless of priority. Check .sys_off_cb for > conflicts instead of .cb_data; some callbacks (e.g. firmware) do not > need any per-instance data, so .cb_data could be NULL. > > Signed-off-by: Samuel Holland <samuel@...lland.org> > --- > > kernel/reboot.c | 10 ++++------ > 1 file changed, 4 insertions(+), 6 deletions(-) > > diff --git a/kernel/reboot.c b/kernel/reboot.c > index 3bba88c7ffc6..38c18d4f0a36 100644 > --- a/kernel/reboot.c > +++ b/kernel/reboot.c > @@ -327,7 +327,7 @@ static int sys_off_notify(struct notifier_block *nb, > return handler->sys_off_cb(&data); > } > > -static struct sys_off_handler platform_sys_off_handler; > +static struct sys_off_handler early_sys_off_handler; > > static struct sys_off_handler *alloc_sys_off_handler(int priority) > { > @@ -338,10 +338,8 @@ static struct sys_off_handler *alloc_sys_off_handler(int priority) > * Platforms like m68k can't allocate sys_off handler dynamically > * at the early boot time because memory allocator isn't available yet. > */ > - if (priority == SYS_OFF_PRIO_PLATFORM) { > - handler = &platform_sys_off_handler; > - if (handler->cb_data) > - return ERR_PTR(-EBUSY); > + if (!early_sys_off_handler.sys_off_cb) { > + handler = &early_sys_off_handler; > } else { > if (system_state > SYSTEM_RUNNING) > flags = GFP_ATOMIC; > @@ -358,7 +356,7 @@ static struct sys_off_handler *alloc_sys_off_handler(int priority) > > static void free_sys_off_handler(struct sys_off_handler *handler) > { > - if (handler == &platform_sys_off_handler) > + if (handler == &early_sys_off_handler) > memset(handler, 0, sizeof(*handler)); > else > kfree(handler); Reviewed-by: Dmitry Osipenko <dmitry.osipenko@...labora.com> -- Best regards, Dmitry
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