| Message ID | E1gXVIY-0008DI-MU@rmk-PC.armlinux.org.uk (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
| Series | Clean up ARM SMP/CPU hotplug implementations | expand |
On 13-12-18, 18:01, Russell King wrote: > diff --git a/arch/arm/mach-spear/generic.h b/arch/arm/mach-spear/generic.h > index 909b97c0b237..815333fc320c 100644 > --- a/arch/arm/mach-spear/generic.h > +++ b/arch/arm/mach-spear/generic.h > @@ -20,6 +20,8 @@ > > #include <asm/mach/time.h> > > +extern volatile int prima2_pen_release; prima2 ? I haven't tried but this may cause build regressions as well, I am surprised on how this passed for you. > extern void spear13xx_timer_init(void); > extern void spear3xx_timer_init(void); > extern struct pl022_ssp_controller pl022_plat_data; > diff --git a/arch/arm/mach-spear/headsmp.S b/arch/arm/mach-spear/headsmp.S > index c52192dc3d9f..6e250b6c0aa2 100644 > --- a/arch/arm/mach-spear/headsmp.S > +++ b/arch/arm/mach-spear/headsmp.S > @@ -43,5 +43,5 @@ pen: ldr r7, [r6] > > .align > 1: .long . > - .long pen_release > + .long spear_pen_release > ENDPROC(spear13xx_secondary_startup) > diff --git a/arch/arm/mach-spear/hotplug.c b/arch/arm/mach-spear/hotplug.c > index 12edd1cf8a12..0dd84f609627 100644 > --- a/arch/arm/mach-spear/hotplug.c > +++ b/arch/arm/mach-spear/hotplug.c > @@ -16,6 +16,8 @@ > #include <asm/cp15.h> > #include <asm/smp_plat.h> > > +#include "generic.h" > + > static inline void cpu_enter_lowpower(void) > { > unsigned int v; > @@ -57,7 +59,7 @@ static inline void spear13xx_do_lowpower(unsigned int cpu, int *spurious) > for (;;) { > wfi(); > > - if (pen_release == cpu) { > + if (spear_pen_release == cpu) { > /* > * OK, proper wakeup, we're done > */ > diff --git a/arch/arm/mach-spear/platsmp.c b/arch/arm/mach-spear/platsmp.c > index 39038a03836a..b1ff4bb86f6d 100644 > --- a/arch/arm/mach-spear/platsmp.c > +++ b/arch/arm/mach-spear/platsmp.c > @@ -20,16 +20,21 @@ > #include <mach/spear.h> > #include "generic.h" > > +/* XXX spear_pen_release is cargo culted code - DO NOT COPY XXX */ > +volatile int spear_pen_release = -1; > + > /* > - * Write pen_release in a way that is guaranteed to be visible to all > - * observers, irrespective of whether they're taking part in coherency > + * XXX CARGO CULTED CODE - DO NOT COPY XXX > + * > + * Write spear_pen_release in a way that is guaranteed to be visible to > + * all observers, irrespective of whether they're taking part in coherency > * or not. This is necessary for the hotplug code to work reliably. > */ > -static void write_pen_release(int val) > +static void spear_write_pen_release(int val) > { > - pen_release = val; > + spear_pen_release = val; > smp_wmb(); > - sync_cache_w(&pen_release); > + sync_cache_w(&spear_pen_release); > } > > static DEFINE_SPINLOCK(boot_lock); > @@ -42,7 +47,7 @@ static void spear13xx_secondary_init(unsigned int cpu) > * let the primary processor know we're out of the > * pen, then head off into the C entry point > */ > - write_pen_release(-1); > + spear_write_pen_release(-1); > > /* > * Synchronise with the boot thread. > @@ -64,17 +69,17 @@ static int spear13xx_boot_secondary(unsigned int cpu, struct task_struct *idle) > /* > * The secondary processor is waiting to be released from > * the holding pen - release it, then wait for it to flag > - * that it has been released by resetting pen_release. > + * that it has been released by resetting spear_pen_release. > * > - * Note that "pen_release" is the hardware CPU ID, whereas > + * Note that "spear_pen_release" is the hardware CPU ID, whereas > * "cpu" is Linux's internal ID. > */ > - write_pen_release(cpu); > + spear_write_pen_release(cpu); > > timeout = jiffies + (1 * HZ); > while (time_before(jiffies, timeout)) { > smp_rmb(); > - if (pen_release == -1) > + if (spear_pen_release == -1) > break; > > udelay(10); > @@ -86,7 +91,7 @@ static int spear13xx_boot_secondary(unsigned int cpu, struct task_struct *idle) > */ > spin_unlock(&boot_lock); > > - return pen_release != -1 ? -ENOSYS : 0; > + return spear_pen_release != -1 ? -ENOSYS : 0; > } > > /* > -- > 2.7.4
On Fri, Dec 14, 2018 at 10:09:23AM +0530, Viresh Kumar wrote: > On 13-12-18, 18:01, Russell King wrote: > > diff --git a/arch/arm/mach-spear/generic.h b/arch/arm/mach-spear/generic.h > > index 909b97c0b237..815333fc320c 100644 > > --- a/arch/arm/mach-spear/generic.h > > +++ b/arch/arm/mach-spear/generic.h > > @@ -20,6 +20,8 @@ > > > > #include <asm/mach/time.h> > > > > +extern volatile int prima2_pen_release; > > prima2 ? > > I haven't tried but this may cause build regressions as well, I am > surprised on how this passed for you. Thanks. These patches aren't all build tested - I don't see the point of wasting hours build testing when these platforms /really/ need something better. This is not supposed to be a finished patch, but a patch to get folk to do something about this issue. Please fix this issue properly. I can't give you a patch to do that, you need to sort it yourself, but failure to do anything _will_ result in an updated version of this patch being merged. > > extern void spear13xx_timer_init(void); > > extern void spear3xx_timer_init(void); > > extern struct pl022_ssp_controller pl022_plat_data; > > diff --git a/arch/arm/mach-spear/headsmp.S b/arch/arm/mach-spear/headsmp.S > > index c52192dc3d9f..6e250b6c0aa2 100644 > > --- a/arch/arm/mach-spear/headsmp.S > > +++ b/arch/arm/mach-spear/headsmp.S > > @@ -43,5 +43,5 @@ pen: ldr r7, [r6] > > > > .align > > 1: .long . > > - .long pen_release > > + .long spear_pen_release > > ENDPROC(spear13xx_secondary_startup) > > diff --git a/arch/arm/mach-spear/hotplug.c b/arch/arm/mach-spear/hotplug.c > > index 12edd1cf8a12..0dd84f609627 100644 > > --- a/arch/arm/mach-spear/hotplug.c > > +++ b/arch/arm/mach-spear/hotplug.c > > @@ -16,6 +16,8 @@ > > #include <asm/cp15.h> > > #include <asm/smp_plat.h> > > > > +#include "generic.h" > > + > > static inline void cpu_enter_lowpower(void) > > { > > unsigned int v; > > @@ -57,7 +59,7 @@ static inline void spear13xx_do_lowpower(unsigned int cpu, int *spurious) > > for (;;) { > > wfi(); > > > > - if (pen_release == cpu) { > > + if (spear_pen_release == cpu) { > > /* > > * OK, proper wakeup, we're done > > */ > > diff --git a/arch/arm/mach-spear/platsmp.c b/arch/arm/mach-spear/platsmp.c > > index 39038a03836a..b1ff4bb86f6d 100644 > > --- a/arch/arm/mach-spear/platsmp.c > > +++ b/arch/arm/mach-spear/platsmp.c > > @@ -20,16 +20,21 @@ > > #include <mach/spear.h> > > #include "generic.h" > > > > +/* XXX spear_pen_release is cargo culted code - DO NOT COPY XXX */ > > +volatile int spear_pen_release = -1; > > + > > /* > > - * Write pen_release in a way that is guaranteed to be visible to all > > - * observers, irrespective of whether they're taking part in coherency > > + * XXX CARGO CULTED CODE - DO NOT COPY XXX > > + * > > + * Write spear_pen_release in a way that is guaranteed to be visible to > > + * all observers, irrespective of whether they're taking part in coherency > > * or not. This is necessary for the hotplug code to work reliably. > > */ > > -static void write_pen_release(int val) > > +static void spear_write_pen_release(int val) > > { > > - pen_release = val; > > + spear_pen_release = val; > > smp_wmb(); > > - sync_cache_w(&pen_release); > > + sync_cache_w(&spear_pen_release); > > } > > > > static DEFINE_SPINLOCK(boot_lock); > > @@ -42,7 +47,7 @@ static void spear13xx_secondary_init(unsigned int cpu) > > * let the primary processor know we're out of the > > * pen, then head off into the C entry point > > */ > > - write_pen_release(-1); > > + spear_write_pen_release(-1); > > > > /* > > * Synchronise with the boot thread. > > @@ -64,17 +69,17 @@ static int spear13xx_boot_secondary(unsigned int cpu, struct task_struct *idle) > > /* > > * The secondary processor is waiting to be released from > > * the holding pen - release it, then wait for it to flag > > - * that it has been released by resetting pen_release. > > + * that it has been released by resetting spear_pen_release. > > * > > - * Note that "pen_release" is the hardware CPU ID, whereas > > + * Note that "spear_pen_release" is the hardware CPU ID, whereas > > * "cpu" is Linux's internal ID. > > */ > > - write_pen_release(cpu); > > + spear_write_pen_release(cpu); > > > > timeout = jiffies + (1 * HZ); > > while (time_before(jiffies, timeout)) { > > smp_rmb(); > > - if (pen_release == -1) > > + if (spear_pen_release == -1) > > break; > > > > udelay(10); > > @@ -86,7 +91,7 @@ static int spear13xx_boot_secondary(unsigned int cpu, struct task_struct *idle) > > */ > > spin_unlock(&boot_lock); > > > > - return pen_release != -1 ? -ENOSYS : 0; > > + return spear_pen_release != -1 ? -ENOSYS : 0; > > } > > > > /* > > -- > > 2.7.4 > > -- > viresh > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
On 14-12-18, 13:12, Russell King - ARM Linux wrote: > On Fri, Dec 14, 2018 at 10:09:23AM +0530, Viresh Kumar wrote: > > On 13-12-18, 18:01, Russell King wrote: > > > diff --git a/arch/arm/mach-spear/generic.h b/arch/arm/mach-spear/generic.h > > > index 909b97c0b237..815333fc320c 100644 > > > --- a/arch/arm/mach-spear/generic.h > > > +++ b/arch/arm/mach-spear/generic.h > > > @@ -20,6 +20,8 @@ > > > > > > #include <asm/mach/time.h> > > > > > > +extern volatile int prima2_pen_release; > > > > prima2 ? > > > > I haven't tried but this may cause build regressions as well, I am > > surprised on how this passed for you. > > Thanks. > > These patches aren't all build tested - Ah okay. > I don't see the point of wasting > hours build testing when these platforms /really/ need something better. I was expecting it to be build tested at least, to be honest. But anyway, we will see build failures from bots if any such cases exist. > This is not supposed to be a finished patch, but a patch to get folk > to do something about this issue. > > Please fix this issue properly. I can't give you a patch to do that, > you need to sort it yourself, but failure to do anything _will_ result > in an updated version of this patch being merged. Yeah, I know. I have seen the thread and it was lack of knowledge in the beginning which made us copy code from rest of ARM platforms. That was stupid and there can't be any excuse for that. Unfortunately, I don't have access to hardware to test this stuff and so wouldn't be possible to send a patch as well. Lets get your patch merged at least.
diff --git a/arch/arm/include/asm/smp.h b/arch/arm/include/asm/smp.h index 709a55989cb0..451ae684aaf4 100644 --- a/arch/arm/include/asm/smp.h +++ b/arch/arm/include/asm/smp.h @@ -67,7 +67,6 @@ struct secondary_data { void *stack; }; extern struct secondary_data secondary_data; -extern volatile int pen_release; extern void secondary_startup(void); extern void secondary_startup_arm(void); diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c index 0978282d5fc2..04aa1bcb8d98 100644 --- a/arch/arm/kernel/smp.c +++ b/arch/arm/kernel/smp.c @@ -61,12 +61,6 @@ */ struct secondary_data secondary_data; -/* - * control for which core is the next to come out of the secondary - * boot "holding pen" - */ -volatile int pen_release = -1; - enum ipi_msg_type { IPI_WAKEUP, IPI_TIMER, diff --git a/arch/arm/mach-exynos/headsmp.S b/arch/arm/mach-exynos/headsmp.S index 005695c9bf40..0ac2cb9a7355 100644 --- a/arch/arm/mach-exynos/headsmp.S +++ b/arch/arm/mach-exynos/headsmp.S @@ -36,4 +36,4 @@ ENDPROC(exynos4_secondary_startup) .align 2 1: .long . - .long pen_release + .long exynos_pen_release diff --git a/arch/arm/mach-exynos/platsmp.c b/arch/arm/mach-exynos/platsmp.c index 6a1e682371b3..76c3f05854e4 100644 --- a/arch/arm/mach-exynos/platsmp.c +++ b/arch/arm/mach-exynos/platsmp.c @@ -28,6 +28,9 @@ extern void exynos4_secondary_startup(void); +/* XXX exynos_pen_release is cargo culted code - DO NOT COPY XXX */ +volatile int exynos_pen_release = -1; + #ifdef CONFIG_HOTPLUG_CPU static inline void cpu_leave_lowpower(u32 core_id) { @@ -57,7 +60,7 @@ static inline void platform_do_lowpower(unsigned int cpu, int *spurious) wfi(); - if (pen_release == core_id) { + if (exynos_pen_release == core_id) { /* * OK, proper wakeup, we're done */ @@ -228,15 +231,17 @@ void exynos_core_restart(u32 core_id) } /* - * Write pen_release in a way that is guaranteed to be visible to all - * observers, irrespective of whether they're taking part in coherency + * XXX CARGO CULTED CODE - DO NOT COPY XXX + * + * Write exynos_pen_release in a way that is guaranteed to be visible to + * all observers, irrespective of whether they're taking part in coherency * or not. This is necessary for the hotplug code to work reliably. */ -static void write_pen_release(int val) +static void exynos_write_pen_release(int val) { - pen_release = val; + exynos_pen_release = val; smp_wmb(); - sync_cache_w(&pen_release); + sync_cache_w(&exynos_pen_release); } static DEFINE_SPINLOCK(boot_lock); @@ -247,7 +252,7 @@ static void exynos_secondary_init(unsigned int cpu) * let the primary processor know we're out of the * pen, then head off into the C entry point */ - write_pen_release(-1); + exynos_write_pen_release(-1); /* * Synchronise with the boot thread. @@ -322,12 +327,12 @@ static int exynos_boot_secondary(unsigned int cpu, struct task_struct *idle) /* * The secondary processor is waiting to be released from * the holding pen - release it, then wait for it to flag - * that it has been released by resetting pen_release. + * that it has been released by resetting exynos_pen_release. * - * Note that "pen_release" is the hardware CPU core ID, whereas + * Note that "exynos_pen_release" is the hardware CPU core ID, whereas * "cpu" is Linux's internal ID. */ - write_pen_release(core_id); + exynos_write_pen_release(core_id); if (!exynos_cpu_power_state(core_id)) { exynos_cpu_power_up(core_id); @@ -376,13 +381,13 @@ static int exynos_boot_secondary(unsigned int cpu, struct task_struct *idle) else arch_send_wakeup_ipi_mask(cpumask_of(cpu)); - if (pen_release == -1) + if (exynos_pen_release == -1) break; udelay(10); } - if (pen_release != -1) + if (exynos_pen_release != -1) ret = -ETIMEDOUT; /* @@ -392,7 +397,7 @@ static int exynos_boot_secondary(unsigned int cpu, struct task_struct *idle) fail: spin_unlock(&boot_lock); - return pen_release != -1 ? ret : 0; + return exynos_pen_release != -1 ? ret : 0; } static void __init exynos_smp_prepare_cpus(unsigned int max_cpus) diff --git a/arch/arm/mach-prima2/common.h b/arch/arm/mach-prima2/common.h index 6d77b622d168..457eb7b18160 100644 --- a/arch/arm/mach-prima2/common.h +++ b/arch/arm/mach-prima2/common.h @@ -15,6 +15,8 @@ #include <asm/mach/time.h> #include <asm/exception.h> +extern volatile int prima2_pen_release; + extern const struct smp_operations sirfsoc_smp_ops; extern void sirfsoc_secondary_startup(void); extern void sirfsoc_cpu_die(unsigned int cpu); diff --git a/arch/arm/mach-prima2/headsmp.S b/arch/arm/mach-prima2/headsmp.S index 209d9fc5c16c..6cf4fc60347b 100644 --- a/arch/arm/mach-prima2/headsmp.S +++ b/arch/arm/mach-prima2/headsmp.S @@ -34,4 +34,4 @@ ENDPROC(sirfsoc_secondary_startup) .align 1: .long . - .long pen_release + .long prima2_pen_release diff --git a/arch/arm/mach-prima2/hotplug.c b/arch/arm/mach-prima2/hotplug.c index a728c78b996f..b6cf1527e330 100644 --- a/arch/arm/mach-prima2/hotplug.c +++ b/arch/arm/mach-prima2/hotplug.c @@ -11,6 +11,7 @@ #include <linux/smp.h> #include <asm/smp_plat.h> +#include "common.h" static inline void platform_do_lowpower(unsigned int cpu) { @@ -18,7 +19,7 @@ static inline void platform_do_lowpower(unsigned int cpu) for (;;) { __asm__ __volatile__("dsb\n\t" "wfi\n\t" : : : "memory"); - if (pen_release == cpu_logical_map(cpu)) { + if (prima2_pen_release == cpu_logical_map(cpu)) { /* * OK, proper wakeup, we're done */ diff --git a/arch/arm/mach-prima2/platsmp.c b/arch/arm/mach-prima2/platsmp.c index 75ef5d4be554..d1f8b5168083 100644 --- a/arch/arm/mach-prima2/platsmp.c +++ b/arch/arm/mach-prima2/platsmp.c @@ -24,13 +24,16 @@ static void __iomem *clk_base; static DEFINE_SPINLOCK(boot_lock); +/* XXX prima2_pen_release is cargo culted code - DO NOT COPY XXX */ +volatile int prima2_pen_release = -1; + static void sirfsoc_secondary_init(unsigned int cpu) { /* * let the primary processor know we're out of the * pen, then head off into the C entry point */ - pen_release = -1; + prima2_pen_release = -1; smp_wmb(); /* @@ -80,13 +83,13 @@ static int sirfsoc_boot_secondary(unsigned int cpu, struct task_struct *idle) /* * The secondary processor is waiting to be released from * the holding pen - release it, then wait for it to flag - * that it has been released by resetting pen_release. + * that it has been released by resetting prima2_pen_release. * - * Note that "pen_release" is the hardware CPU ID, whereas + * Note that "prima2_pen_release" is the hardware CPU ID, whereas * "cpu" is Linux's internal ID. */ - pen_release = cpu_logical_map(cpu); - sync_cache_w(&pen_release); + prima2_pen_release = cpu_logical_map(cpu); + sync_cache_w(&prima2_pen_release); /* * Send the secondary CPU SEV, thereby causing the boot monitor to read @@ -97,7 +100,7 @@ static int sirfsoc_boot_secondary(unsigned int cpu, struct task_struct *idle) timeout = jiffies + (1 * HZ); while (time_before(jiffies, timeout)) { smp_rmb(); - if (pen_release == -1) + if (prima2_pen_release == -1) break; udelay(10); @@ -109,7 +112,7 @@ static int sirfsoc_boot_secondary(unsigned int cpu, struct task_struct *idle) */ spin_unlock(&boot_lock); - return pen_release != -1 ? -ENOSYS : 0; + return prima2_pen_release != -1 ? -ENOSYS : 0; } const struct smp_operations sirfsoc_smp_ops __initconst = { diff --git a/arch/arm/mach-spear/generic.h b/arch/arm/mach-spear/generic.h index 909b97c0b237..815333fc320c 100644 --- a/arch/arm/mach-spear/generic.h +++ b/arch/arm/mach-spear/generic.h @@ -20,6 +20,8 @@ #include <asm/mach/time.h> +extern volatile int prima2_pen_release; + extern void spear13xx_timer_init(void); extern void spear3xx_timer_init(void); extern struct pl022_ssp_controller pl022_plat_data; diff --git a/arch/arm/mach-spear/headsmp.S b/arch/arm/mach-spear/headsmp.S index c52192dc3d9f..6e250b6c0aa2 100644 --- a/arch/arm/mach-spear/headsmp.S +++ b/arch/arm/mach-spear/headsmp.S @@ -43,5 +43,5 @@ pen: ldr r7, [r6] .align 1: .long . - .long pen_release + .long spear_pen_release ENDPROC(spear13xx_secondary_startup) diff --git a/arch/arm/mach-spear/hotplug.c b/arch/arm/mach-spear/hotplug.c index 12edd1cf8a12..0dd84f609627 100644 --- a/arch/arm/mach-spear/hotplug.c +++ b/arch/arm/mach-spear/hotplug.c @@ -16,6 +16,8 @@ #include <asm/cp15.h> #include <asm/smp_plat.h> +#include "generic.h" + static inline void cpu_enter_lowpower(void) { unsigned int v; @@ -57,7 +59,7 @@ static inline void spear13xx_do_lowpower(unsigned int cpu, int *spurious) for (;;) { wfi(); - if (pen_release == cpu) { + if (spear_pen_release == cpu) { /* * OK, proper wakeup, we're done */ diff --git a/arch/arm/mach-spear/platsmp.c b/arch/arm/mach-spear/platsmp.c index 39038a03836a..b1ff4bb86f6d 100644 --- a/arch/arm/mach-spear/platsmp.c +++ b/arch/arm/mach-spear/platsmp.c @@ -20,16 +20,21 @@ #include <mach/spear.h> #include "generic.h" +/* XXX spear_pen_release is cargo culted code - DO NOT COPY XXX */ +volatile int spear_pen_release = -1; + /* - * Write pen_release in a way that is guaranteed to be visible to all - * observers, irrespective of whether they're taking part in coherency + * XXX CARGO CULTED CODE - DO NOT COPY XXX + * + * Write spear_pen_release in a way that is guaranteed to be visible to + * all observers, irrespective of whether they're taking part in coherency * or not. This is necessary for the hotplug code to work reliably. */ -static void write_pen_release(int val) +static void spear_write_pen_release(int val) { - pen_release = val; + spear_pen_release = val; smp_wmb(); - sync_cache_w(&pen_release); + sync_cache_w(&spear_pen_release); } static DEFINE_SPINLOCK(boot_lock); @@ -42,7 +47,7 @@ static void spear13xx_secondary_init(unsigned int cpu) * let the primary processor know we're out of the * pen, then head off into the C entry point */ - write_pen_release(-1); + spear_write_pen_release(-1); /* * Synchronise with the boot thread. @@ -64,17 +69,17 @@ static int spear13xx_boot_secondary(unsigned int cpu, struct task_struct *idle) /* * The secondary processor is waiting to be released from * the holding pen - release it, then wait for it to flag - * that it has been released by resetting pen_release. + * that it has been released by resetting spear_pen_release. * - * Note that "pen_release" is the hardware CPU ID, whereas + * Note that "spear_pen_release" is the hardware CPU ID, whereas * "cpu" is Linux's internal ID. */ - write_pen_release(cpu); + spear_write_pen_release(cpu); timeout = jiffies + (1 * HZ); while (time_before(jiffies, timeout)) { smp_rmb(); - if (pen_release == -1) + if (spear_pen_release == -1) break; udelay(10); @@ -86,7 +91,7 @@ static int spear13xx_boot_secondary(unsigned int cpu, struct task_struct *idle) */ spin_unlock(&boot_lock); - return pen_release != -1 ? -ENOSYS : 0; + return spear_pen_release != -1 ? -ENOSYS : 0; } /*
Consolidating the "pen_release" stuff amongst the various SoC implementations gives credence to having a CPU holding pen for secondary CPUs. However, this is far from the truth. Many SoC implementations cargo-cult copied various bits of the pen release implementation from the initial Realview/Versatile Express implementation without understanding what it was or why it existed. The reason it existed is because these are _development_ platforms, and some board firmware is unable to individually control the startup of secondary CPUs. Moreover, they do not have a way to power down or reset secondary CPUs for hot-unplug. Hence, the pen_release implementation was designed for ARM Ltd's development platforms to provide a working implementation, even though it is very far from what is required. It was decided a while back to reduce the duplication by consolidating the "pen_release" variable, but this only made the situation worse - we have ended up with several implementations that read this variable but do not write it - again, showing the cargo-cult mentality at work, lack of proper review of new code, and in some cases a lack of testing. While it would be preferable to remove pen_release entirely from the kernel, this is not possible without help from the SoC maintainers, which seems to be lacking. However, I want to remove pen_release from arch code to remove the credence that having it gives. This patch removes pen_release from the arch code entirely, adding private per-SoC definitions for it instead, and explicitly stating that write_pen_release() is cargo-cult copied and should not be copied any further. Rename write_pen_release() in a similar fashion as well. Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk> --- arch/arm/include/asm/smp.h | 1 - arch/arm/kernel/smp.c | 6 ------ arch/arm/mach-exynos/headsmp.S | 2 +- arch/arm/mach-exynos/platsmp.c | 31 ++++++++++++++++++------------- arch/arm/mach-prima2/common.h | 2 ++ arch/arm/mach-prima2/headsmp.S | 2 +- arch/arm/mach-prima2/hotplug.c | 3 ++- arch/arm/mach-prima2/platsmp.c | 17 ++++++++++------- arch/arm/mach-spear/generic.h | 2 ++ arch/arm/mach-spear/headsmp.S | 2 +- arch/arm/mach-spear/hotplug.c | 4 +++- arch/arm/mach-spear/platsmp.c | 27 ++++++++++++++++----------- 12 files changed, 56 insertions(+), 43 deletions(-)