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Open Source and information security mailing list archives
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Date: Fri, 29 Apr 2022 11:34:51 -0300 From: "Guilherme G. Piccoli" <gpiccoli@...lia.com> To: Helge Deller <deller@....de>, akpm@...ux-foundation.org, bhe@...hat.com, pmladek@...e.com, kexec@...ts.infradead.org Cc: linux-kernel@...r.kernel.org, bcm-kernel-feedback-list@...adcom.com, linuxppc-dev@...ts.ozlabs.org, linux-alpha@...r.kernel.org, linux-edac@...r.kernel.org, linux-hyperv@...r.kernel.org, linux-leds@...r.kernel.org, linux-mips@...r.kernel.org, linux-parisc@...r.kernel.org, linux-pm@...r.kernel.org, linux-remoteproc@...r.kernel.org, linux-s390@...r.kernel.org, linux-tegra@...r.kernel.org, linux-um@...ts.infradead.org, linux-xtensa@...ux-xtensa.org, netdev@...r.kernel.org, openipmi-developer@...ts.sourceforge.net, rcu@...r.kernel.org, sparclinux@...r.kernel.org, xen-devel@...ts.xenproject.org, x86@...nel.org, kernel-dev@...lia.com, kernel@...ccoli.net, halves@...onical.com, fabiomirmar@...il.com, alejandro.j.jimenez@...cle.com, andriy.shevchenko@...ux.intel.com, arnd@...db.de, bp@...en8.de, corbet@....net, d.hatayama@...fujitsu.com, dave.hansen@...ux.intel.com, dyoung@...hat.com, feng.tang@...el.com, gregkh@...uxfoundation.org, mikelley@...rosoft.com, hidehiro.kawai.ez@...achi.com, jgross@...e.com, john.ogness@...utronix.de, keescook@...omium.org, luto@...nel.org, mhiramat@...nel.org, mingo@...hat.com, paulmck@...nel.org, peterz@...radead.org, rostedt@...dmis.org, senozhatsky@...omium.org, stern@...land.harvard.edu, tglx@...utronix.de, vgoyal@...hat.com, vkuznets@...hat.com, will@...nel.org, "James E.J. Bottomley" <James.Bottomley@...senPartnership.com> Subject: Re: [PATCH 12/30] parisc: Replace regular spinlock with spin_trylock on panic path On 28/04/2022 13:55, Helge Deller wrote: > [...] > You may add: > Acked-by: Helge Deller <deller@....de> # parisc > > Helge Thanks Helge, added! Cheers, Guilherme > > >> --- >> arch/parisc/include/asm/pdc.h | 1 + >> arch/parisc/kernel/firmware.c | 27 +++++++++++++++++++++++---- >> drivers/parisc/power.c | 17 ++++++++++------- >> 3 files changed, 34 insertions(+), 11 deletions(-) >> >> diff --git a/arch/parisc/include/asm/pdc.h b/arch/parisc/include/asm/pdc.h >> index b643092d4b98..7a106008e258 100644 >> --- a/arch/parisc/include/asm/pdc.h >> +++ b/arch/parisc/include/asm/pdc.h >> @@ -83,6 +83,7 @@ int pdc_do_firm_test_reset(unsigned long ftc_bitmap); >> int pdc_do_reset(void); >> int pdc_soft_power_info(unsigned long *power_reg); >> int pdc_soft_power_button(int sw_control); >> +int pdc_soft_power_button_panic(int sw_control); >> void pdc_io_reset(void); >> void pdc_io_reset_devices(void); >> int pdc_iodc_getc(void); >> diff --git a/arch/parisc/kernel/firmware.c b/arch/parisc/kernel/firmware.c >> index 6a7e315bcc2e..0e2f70b592f4 100644 >> --- a/arch/parisc/kernel/firmware.c >> +++ b/arch/parisc/kernel/firmware.c >> @@ -1232,15 +1232,18 @@ int __init pdc_soft_power_info(unsigned long *power_reg) >> } >> >> /* >> - * pdc_soft_power_button - Control the soft power button behaviour >> - * @sw_control: 0 for hardware control, 1 for software control >> + * pdc_soft_power_button{_panic} - Control the soft power button behaviour >> + * @sw_control: 0 for hardware control, 1 for software control >> * >> * >> * This PDC function places the soft power button under software or >> * hardware control. >> - * Under software control the OS may control to when to allow to shut >> - * down the system. Under hardware control pressing the power button >> + * Under software control the OS may control to when to allow to shut >> + * down the system. Under hardware control pressing the power button >> * powers off the system immediately. >> + * >> + * The _panic version relies in spin_trylock to prevent deadlock >> + * on panic path. >> */ >> int pdc_soft_power_button(int sw_control) >> { >> @@ -1254,6 +1257,22 @@ int pdc_soft_power_button(int sw_control) >> return retval; >> } >> >> +int pdc_soft_power_button_panic(int sw_control) >> +{ >> + int retval; >> + unsigned long flags; >> + >> + if (!spin_trylock_irqsave(&pdc_lock, flags)) { >> + pr_emerg("Couldn't enable soft power button\n"); >> + return -EBUSY; /* ignored by the panic notifier */ >> + } >> + >> + retval = mem_pdc_call(PDC_SOFT_POWER, PDC_SOFT_POWER_ENABLE, __pa(pdc_result), sw_control); >> + spin_unlock_irqrestore(&pdc_lock, flags); >> + >> + return retval; >> +} >> + >> /* >> * pdc_io_reset - Hack to avoid overlapping range registers of Bridges devices. >> * Primarily a problem on T600 (which parisc-linux doesn't support) but >> diff --git a/drivers/parisc/power.c b/drivers/parisc/power.c >> index 456776bd8ee6..8512884de2cf 100644 >> --- a/drivers/parisc/power.c >> +++ b/drivers/parisc/power.c >> @@ -37,7 +37,6 @@ >> #include <linux/module.h> >> #include <linux/init.h> >> #include <linux/kernel.h> >> -#include <linux/notifier.h> >> #include <linux/panic_notifier.h> >> #include <linux/reboot.h> >> #include <linux/sched/signal.h> >> @@ -175,16 +174,21 @@ static void powerfail_interrupt(int code, void *x) >> >> >> >> -/* parisc_panic_event() is called by the panic handler. >> - * As soon as a panic occurs, our tasklets above will not be >> - * executed any longer. This function then re-enables the >> - * soft-power switch and allows the user to switch off the system >> +/* >> + * parisc_panic_event() is called by the panic handler. >> + * >> + * As soon as a panic occurs, our tasklets above will not >> + * be executed any longer. This function then re-enables >> + * the soft-power switch and allows the user to switch off >> + * the system. We rely in pdc_soft_power_button_panic() >> + * since this version spin_trylocks (instead of regular >> + * spinlock), preventing deadlocks on panic path. >> */ >> static int parisc_panic_event(struct notifier_block *this, >> unsigned long event, void *ptr) >> { >> /* re-enable the soft-power switch */ >> - pdc_soft_power_button(0); >> + pdc_soft_power_button_panic(0); >> return NOTIFY_DONE; >> } >> >> @@ -193,7 +197,6 @@ static struct notifier_block parisc_panic_block = { >> .priority = INT_MAX, >> }; >> >> - >> static int __init power_init(void) >> { >> unsigned long ret; >
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