diff options
| author | Guilherme G. Piccoli <gpiccoli@igalia.com> | 2023-02-20 18:11:05 -0300 |
|---|---|---|
| committer | Helge Deller <deller@gmx.de> | 2023-05-03 17:43:26 +0200 |
| commit | 829632dae8321787525ee37dc4828bbe6edafdae (patch) | |
| tree | ed3c7d2bf77f2ad379e8655759ba18a3c24f0d60 /arch | |
| parent | e0838a99289e013d17496ed9464c3cf71d49b977 (diff) | |
parisc: Replace regular spinlock with spin_trylock on panic path
The panic notifiers' callbacks execute in an atomic context, with
interrupts/preemption disabled, and all CPUs not running the panic
function are off, so it's very dangerous to wait on a regular
spinlock, there's a risk of deadlock.
Refactor the panic notifier of parisc/power driver to make use
of spin_trylock - for that, we've added a second version of the
soft-power function. Also, some comments were reorganized and
trailing white spaces, useless header inclusion and blank lines
were removed.
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Jeroen Roovers <jer@xs4all.nl>
Acked-by: Helge Deller <deller@gmx.de> # parisc
Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
Signed-off-by: Helge Deller <deller@gmx.de>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/parisc/include/asm/pdc.h | 1 | ||||
| -rw-r--r-- | arch/parisc/kernel/firmware.c | 27 |
2 files changed, 24 insertions, 4 deletions
diff --git a/arch/parisc/include/asm/pdc.h b/arch/parisc/include/asm/pdc.h index 40793bef8429..2b4fad8328e8 100644 --- a/arch/parisc/include/asm/pdc.h +++ b/arch/parisc/include/asm/pdc.h @@ -80,6 +80,7 @@ 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 6817892a2c58..cc124d9f1f7f 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 on 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 |