linux-kernel - Re: [PATCH 12/14] x86 ioapic: Simplify probe_nr_irqs

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Date:	Mon, 29 Mar 2010 19:16:10 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
Cc:	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	linux-kernel@...r.kernel.org, Thomas Renninger <trenn@...e.de>,
	Suresh Siddha <suresh.b.siddha@...el.com>, len.brown@...el.com,
	Tony Luck <tony.luck@...el.com>,
	Fenghua Yu <fenghua.yu@...el.com>, linux-acpi@...r.kernel.org,
	Iranna D Ankad <iranna.ankad@...ibm.com>,
	Gary Hade <garyhade@...ibm.com>,
	Natalie Protasevich <protasnb@...il.com>
Subject: Re: [PATCH 12/14] x86 ioapic: Simplify probe_nr_irqs_gsi.

On Mon, Mar 29, 2010 at 4:20 PM, Eric W. Biederman
<ebiederm@...ssion.com> wrote:
> From: Eric W. Biederman <ebiederm@...ssion.com>
>
> Use the global gsi_end value now that all ioapics have
> valid gsi numbers instead of a combination of acpi_probe_gsi
> and walking all of the ioapics and couting their number of
> entries by hand if acpi_probe_gsi gave us an answer we did
> not like.
>
> This fixes a small bug in probe_nr_irqs_gsi.  Previously
> acpi_probe_gsi unnecessarily added 1 to the maximum
> gsi_end value.  gsi_end is already one past the end of
> the number of gsi's so the additional increment was
> superfluous.
>
> Signed-off-by: Eric W. Biederman <ebiederm@...ssion.com>
> ---
>  arch/x86/include/asm/mpspec.h  |    6 ------
>  arch/x86/kernel/acpi/boot.c    |   23 -----------------------
>  arch/x86/kernel/apic/io_apic.c |   17 +++--------------
>  3 files changed, 3 insertions(+), 43 deletions(-)
>
> diff --git a/arch/x86/include/asm/mpspec.h b/arch/x86/include/asm/mpspec.h
> index 29994f0..c82868e 100644
> --- a/arch/x86/include/asm/mpspec.h
> +++ b/arch/x86/include/asm/mpspec.h
> @@ -105,12 +105,6 @@ extern void mp_config_acpi_legacy_irqs(void);
>  struct device;
>  extern int mp_register_gsi(struct device *dev, u32 gsi, int edge_level,
>                                 int active_high_low);
> -extern int acpi_probe_gsi(void);
> -#else /* !CONFIG_ACPI: */
> -static inline int acpi_probe_gsi(void)
> -{
> -       return 0;
> -}
>  #endif /* CONFIG_ACPI */
>
>  #define PHYSID_ARRAY_SIZE      BITS_TO_LONGS(MAX_APICS)
> diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
> index 9c48e99..0e514a1 100644
> --- a/arch/x86/kernel/acpi/boot.c
> +++ b/arch/x86/kernel/acpi/boot.c
> @@ -875,29 +875,6 @@ static int __init acpi_parse_madt_lapic_entries(void)
>  extern int es7000_plat;
>  #endif
>
> -int __init acpi_probe_gsi(void)
> -{
> -       int idx;
> -       int gsi;
> -       int max_gsi = 0;
> -
> -       if (acpi_disabled)
> -               return 0;
> -
> -       if (!acpi_ioapic)
> -               return 0;
> -
> -       max_gsi = 0;
> -       for (idx = 0; idx < nr_ioapics; idx++) {
> -               gsi = mp_gsi_routing[idx].gsi_end;
> -
> -               if (gsi > max_gsi)
> -                       max_gsi = gsi;
> -       }
> -
> -       return max_gsi + 1;
> -}
> -
>  static void assign_to_mp_irq(struct mpc_intsrc *m,
>                                    struct mpc_intsrc *mp_irq)
>  {
> diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
> index 996cf8f..b57b7a3 100644
> --- a/arch/x86/kernel/apic/io_apic.c
> +++ b/arch/x86/kernel/apic/io_apic.c
> @@ -3837,22 +3837,11 @@ int __init io_apic_get_redir_entries (int ioapic)
>
>  void __init probe_nr_irqs_gsi(void)
>  {
> -       int nr = 0;
> +       int nr;
>
> -       nr = acpi_probe_gsi();
> -       if (nr > nr_irqs_gsi) {
> +       nr = gsi_end;

you may need +1 here

YH

> +       if (nr > nr_irqs_gsi)
>                nr_irqs_gsi = nr;
> -       } else {
> -               /* for acpi=off or acpi is not compiled in */
> -               int idx;
> -
> -               nr = 0;
> -               for (idx = 0; idx < nr_ioapics; idx++)
> -                       nr += io_apic_get_redir_entries(idx) + 1;
> -
> -               if (nr > nr_irqs_gsi)
> -                       nr_irqs_gsi = nr;
> -       }
>
>        printk(KERN_DEBUG "nr_irqs_gsi: %d\n", nr_irqs_gsi);
>  }
--
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