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| author | Guilherme G. Piccoli <gpiccoli@igalia.com> | 2023-02-20 18:11:05 -0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-05-24 17:32:42 +0100 |
| commit | c9888aaed1a25a0d89495e7b525136eb7b8b4faf (patch) | |
| tree | 503798a281a8278738bee940b673981ea0f556be /arch/parisc | |
| parent | e112b2e265690f6549357d511ccb4e7d5692cf4d (diff) | |
| download | linux-c9888aaed1a25a0d89495e7b525136eb7b8b4faf.tar.gz | |
parisc: Replace regular spinlock with spin_trylock on panic path
[ Upstream commit 829632dae8321787525ee37dc4828bbe6edafdae ] 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> Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'arch/parisc')
| -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 fcbcf9a96c11..77622558bf65 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 bd325f2b5349..3e051a973e9b 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 |