Re: [PATCH 1/1] MM: slqb, fix per_cpu access

[Dave Young]

On Mon, Nov 2, 2009 at 4:49 PM, Jiri Slaby <jirislaby@xxxxxxxxx> wrote:
> We cannot use the same local variable name as the declared per_cpu
> variable since commit "percpu: remove per_cpu__ prefix."
>
> Otherwise we would see crashes like:
> general protection fault: 0000 [#1] SMP
> last sysfs file:
> CPU 1
> Modules linked in:
> Pid: 1, comm: swapper Tainted: G Â Â Â ÂW Â2.6.32-rc5-mm1_64 #860
> RIP: 0010:[<ffffffff8142ff94>] Â[<ffffffff8142ff94>] start_cpu_timer+0x2b/0x87
> ...
>
> Use slqb_ prefix for the global variable so that we don't collide
> even with the rest of the kernel (s390 and alpha need this).
>
> Signed-off-by: Jiri Slaby <jirislaby@xxxxxxxxx>
> Cc: Nick Piggin <npiggin@xxxxxxx>
> Cc: Tejun Heo <tj@xxxxxxxxxx>
> Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
> Cc: Christoph Lameter <cl@xxxxxxxxxxxxxxxxxxxx>

Tested-by: Dave Young <hidave.darkstar@xxxxxxxxx>

> ---
> Âmm/slqb.c | Â 10 ++++++----
> Â1 files changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/mm/slqb.c b/mm/slqb.c
> index e745d9a..e4bb53f 100644
> --- a/mm/slqb.c
> +++ b/mm/slqb.c
> @@ -2766,11 +2766,12 @@ out:
> Â Â Â Âschedule_delayed_work(work, round_jiffies_relative(3*HZ));
> Â}
>
> -static DEFINE_PER_CPU(struct delayed_work, cache_trim_work);
> +static DEFINE_PER_CPU(struct delayed_work, slqb_cache_trim_work);
>
> Âstatic void __cpuinit start_cpu_timer(int cpu)
> Â{
> - Â Â Â struct delayed_work *cache_trim_work = &per_cpu(cache_trim_work, cpu);
> + Â Â Â struct delayed_work *cache_trim_work = &per_cpu(slqb_cache_trim_work,
> + Â Â Â Â Â Â Â Â Â Â Â cpu);
>
> Â Â Â Â/*
> Â Â Â Â * When this gets called from do_initcalls via cpucache_init(),
> @@ -3136,8 +3137,9 @@ static int __cpuinit slab_cpuup_callback(struct notifier_block *nfb,
>
> Â Â Â Âcase CPU_DOWN_PREPARE:
> Â Â Â Âcase CPU_DOWN_PREPARE_FROZEN:
> - Â Â Â Â Â Â Â cancel_rearming_delayed_work(&per_cpu(cache_trim_work, cpu));
> - Â Â Â Â Â Â Â per_cpu(cache_trim_work, cpu).work.func = NULL;
> + Â Â Â Â Â Â Â cancel_rearming_delayed_work(&per_cpu(slqb_cache_trim_work,
> + Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â cpu));
> + Â Â Â Â Â Â Â per_cpu(slqb_cache_trim_work, cpu).work.func = NULL;
> Â Â Â Â Â Â Â Âbreak;
>
> Â Â Â Âcase CPU_UP_CANCELED:
> --
> 1.6.4.2
>
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-- 
Regards
dave
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