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Date: Mon, 12 Oct 2009 18:23:17 +0200
From: Ingo Molnar <mingo@...e.hu>
To: Dimitri Sivanich <sivanich@....com>
Cc: linux-kernel@...r.kernel.org, "H. Peter Anvin" <hpa@...or.com>,
Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH] x86 UV: Fixes for UV rtc timers
* Dimitri Sivanich <sivanich@....com> wrote:
> Miscellaneous fixes and cleanup for uv rtc timers.
>
> Signed-off-by: Dimitri Sivanich <sivanich@....com>
>
> ---
>
> arch/x86/kernel/irq.c | 10 +----
> arch/x86/kernel/uv_time.c | 81 +++++++++++++++++++++++++++++-------------
> 2 files changed, 58 insertions(+), 33 deletions(-)
>
> Index: linux/arch/x86/kernel/uv_time.c
> ===================================================================
> --- linux.orig/arch/x86/kernel/uv_time.c 2009-10-08 11:31:05.000000000 -0500
> +++ linux/arch/x86/kernel/uv_time.c 2009-10-09 07:49:05.000000000 -0500
> @@ -25,6 +25,7 @@
> #include <asm/uv/bios.h>
> #include <asm/uv/uv.h>
> #include <asm/apic.h>
> +#include <asm/idle.h>
> #include <asm/cpu.h>
>
> #define RTC_NAME "sgi_rtc"
> @@ -75,6 +76,7 @@ struct uv_rtc_timer_head {
> static struct uv_rtc_timer_head **blade_info __read_mostly;
>
> static int uv_rtc_enable;
> +static int uv_rtc_evt_enable;
>
> /*
> * Hardware interface routines
> @@ -123,7 +125,10 @@ static int uv_setup_intr(int cpu, u64 ex
> /* Initialize comparator value */
> uv_write_global_mmr64(pnode, UVH_INT_CMPB, expires);
>
> - return (expires < uv_read_rtc(NULL) && !uv_intr_pending(pnode));
> + if (uv_read_rtc(NULL) <= expires)
> + return 0;
> +
> + return !uv_intr_pending(pnode);
> }
>
> /*
> @@ -223,6 +228,7 @@ static int uv_rtc_set_timer(int cpu, u64
>
> next_cpu = head->next_cpu;
> *t = expires;
> +
> /* Will this one be next to go off? */
> if (next_cpu < 0 || bcpu == next_cpu ||
> expires < head->cpu[next_cpu].expires) {
> @@ -231,7 +237,7 @@ static int uv_rtc_set_timer(int cpu, u64
> *t = ULLONG_MAX;
> uv_rtc_find_next_timer(head, pnode);
> spin_unlock_irqrestore(&head->lock, flags);
> - return 1;
> + return -ETIME;
> }
> }
>
> @@ -244,7 +250,7 @@ static int uv_rtc_set_timer(int cpu, u64
> *
> * Returns 1 if this timer was pending.
> */
> -static int uv_rtc_unset_timer(int cpu)
> +static int uv_rtc_unset_timer(int cpu, int force)
> {
> int pnode = uv_cpu_to_pnode(cpu);
> int bid = uv_cpu_to_blade_id(cpu);
> @@ -256,14 +262,15 @@ static int uv_rtc_unset_timer(int cpu)
>
> spin_lock_irqsave(&head->lock, flags);
>
> - if (head->next_cpu == bcpu && uv_read_rtc(NULL) >= *t)
> + if ((head->next_cpu == bcpu && uv_read_rtc(NULL) >= *t) || force)
> rc = 1;
>
> - *t = ULLONG_MAX;
> -
> - /* Was the hardware setup for this timer? */
> - if (head->next_cpu == bcpu)
> - uv_rtc_find_next_timer(head, pnode);
> + if (rc) {
> + *t = ULLONG_MAX;
> + /* Was the hardware setup for this timer? */
> + if (head->next_cpu == bcpu)
> + uv_rtc_find_next_timer(head, pnode);
> + }
>
> spin_unlock_irqrestore(&head->lock, flags);
>
> @@ -310,7 +317,7 @@ static void uv_rtc_timer_setup(enum cloc
> break;
> case CLOCK_EVT_MODE_UNUSED:
> case CLOCK_EVT_MODE_SHUTDOWN:
> - uv_rtc_unset_timer(ced_cpu);
> + uv_rtc_unset_timer(ced_cpu, 1);
> break;
> }
> }
> @@ -320,13 +327,21 @@ static void uv_rtc_interrupt(void)
> struct clock_event_device *ced = &__get_cpu_var(cpu_ced);
> int cpu = smp_processor_id();
>
> + exit_idle();
> +
> + irq_enter();
> +
> + ack_APIC_irq();
> +
> if (!ced || !ced->event_handler)
> - return;
> + goto out;
>
> - if (uv_rtc_unset_timer(cpu) != 1)
> - return;
> + if (uv_rtc_unset_timer(cpu, 0) != 1)
> + goto out;
>
> ced->event_handler(ced);
> +out:
> + irq_exit();
> }
>
> static int __init uv_enable_rtc(char *str)
> @@ -337,6 +352,14 @@ static int __init uv_enable_rtc(char *st
> }
> __setup("uvrtc", uv_enable_rtc);
>
> +static int __init uv_enable_evt_rtc(char *str)
> +{
> + uv_rtc_evt_enable = 1;
> +
> + return 1;
> +}
> +__setup("uvrtcevt", uv_enable_evt_rtc);
> +
> static __init void uv_rtc_register_clockevents(struct work_struct *dummy)
> {
> struct clock_event_device *ced = &__get_cpu_var(cpu_ced);
> @@ -353,24 +376,25 @@ static __init int uv_rtc_setup_clock(voi
> if (!uv_rtc_enable || !is_uv_system() || generic_interrupt_extension)
> return -ENODEV;
>
> - generic_interrupt_extension = uv_rtc_interrupt;
> -
> clocksource_uv.mult = clocksource_hz2mult(sn_rtc_cycles_per_second,
> clocksource_uv.shift);
>
> rc = clocksource_register(&clocksource_uv);
> - if (rc) {
> - generic_interrupt_extension = NULL;
> + if (rc)
> + printk(KERN_INFO "UV RTC clocksource failed rc %d\n", rc);
> + else
> + printk(KERN_INFO "UV RTC clocksource registered freq %lu MHz\n",
> + sn_rtc_cycles_per_second/(unsigned long)1E6);
> +
> + if (rc || !uv_rtc_evt_enable)
> return rc;
> - }
> +
> + generic_interrupt_extension = uv_rtc_interrupt;
>
> /* Setup and register clockevents */
> rc = uv_rtc_allocate_timers();
> - if (rc) {
> - clocksource_unregister(&clocksource_uv);
> - generic_interrupt_extension = NULL;
> - return rc;
> - }
> + if (rc)
> + goto error;
>
> clock_event_device_uv.mult = div_sc(sn_rtc_cycles_per_second,
> NSEC_PER_SEC, clock_event_device_uv.shift);
> @@ -383,10 +407,17 @@ static __init int uv_rtc_setup_clock(voi
>
> rc = schedule_on_each_cpu(uv_rtc_register_clockevents);
> if (rc) {
> - clocksource_unregister(&clocksource_uv);
> - generic_interrupt_extension = NULL;
> uv_rtc_deallocate_timers();
> + goto error;
> }
> + printk(KERN_INFO "UV RTC clockevents registered\n");
> +
> + return 0;
> +
> +error:
> + generic_interrupt_extension = NULL;
> + clocksource_unregister(&clocksource_uv);
> + printk(KERN_INFO "UV RTC clockevents failed rc %d\n", rc);
>
> return rc;
> }
> Index: linux/arch/x86/kernel/irq.c
> ===================================================================
> --- linux.orig/arch/x86/kernel/irq.c 2009-10-08 11:31:05.000000000 -0500
> +++ linux/arch/x86/kernel/irq.c 2009-10-08 11:31:15.000000000 -0500
> @@ -257,18 +257,12 @@ void smp_generic_interrupt(struct pt_reg
> {
> struct pt_regs *old_regs = set_irq_regs(regs);
>
> - ack_APIC_irq();
> -
> - exit_idle();
> -
> - irq_enter();
> -
> inc_irq_stat(generic_irqs);
>
> if (generic_interrupt_extension)
> generic_interrupt_extension();
> -
> - irq_exit();
> + else
> + ack_APIC_irq();
>
> set_irq_regs(old_regs);
> }
hm, why is the (unnecessary seeming) pushing of the
ack/exit_idle()/irq_enter()/irq_exit() sequence into the
generic_interrupt_extension() function a cleanup?
Also, the commit log is rather terse - what is being fixed and why isnt
it separate from any cleanups?
Ingo
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