Re: [PATCH] x86, acpi_cpufreq: Fix the NULL pointer dereference in get_measured_perf

["Zhang, Yanmin" <yanmin_zhang@linux.intel.com>]

On Wed, 2009-04-15 at 10:37 -0700, Pallipadi, Venkatesh wrote:
> Patch below fixes the problem. 


> Yanmin can you please verify.
It does work.


> Len please push this patch along to linus.
> 
> Thanks,
> Venki
> 
> 
> Fix for a regression that was introduced by earlier commit
> 
> commit 18b2646fe3babeb40b34a0c1751e0bf5adfdc64c
> Author: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
> Date:   Mon Apr 6 11:26:08 2009 -0700
> 
> Regression resulted in the below error happened on systems with
> software coordination where per_cpu acpi data will not be initiated for
> secondary CPUs in a P-state domain.
> 
> On Tue, 2009-04-14 at 23:01 -0700, Zhang, Yanmin wrote:
>  My machine hanged with kernel 2.6.30-rc2 when script read
> > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor.
> >
> > opps happens in get_measured_perf:
> >
> >         cur.aperf.whole = readin.aperf.whole -
> >                                 per_cpu(drv_data, cpu)->saved_aperf;
> >
> > Because per_cpu(drv_data, cpu)=NULL.
> >
> > So function get_measured_perf should check if (per_cpu(drv_data,
> > cpu)==NULL)
> > and return 0 if it's NULL.
> 
> --------------sys log------------------
> 
> BUG: unable to handle kernel NULL pointer dereference at
> 0000000000000020
> IP: [<ffffffff8021af75>] get_measured_perf+0x4a/0xf9
> PGD a7dd88067 PUD a7ccf5067 PMD 0
> Oops: 0000 [#1] SMP
> last sysfs file: /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
> CPU 0
> Modules linked in: video output
> Pid: 2091, comm: kondemand/0 Not tainted 2.6.30-rc2 #1 MP Server
> RIP: 0010:[<ffffffff8021af75>]  [<ffffffff8021af75>]
> get_measured_perf+0x4a/0xf9
> RSP: 0018:ffff880a7d56de20  EFLAGS: 00010246
> RAX: 0000000000000000 RBX: 00000046241a42b6 RCX: ffff88004d219000
> RDX: 000000000000b660 RSI: 0000000000000020 RDI: 0000000000000001
> RBP: ffff880a7f052000 R08: 00000046241a42b6 R09: ffffffff807639f0
> R10: 00000000ffffffea R11: ffffffff802207f4 R12: ffff880a7f052000
> R13: ffff88004d20e460 R14: 0000000000ddd5a6 R15: 0000000000000001
> FS:  0000000000000000(0000) GS:ffff88004d200000(0000)
> knlGS:0000000000000000
> CS:  0010 DS: 0018 ES: 0018 CR0: 000000008005003b
> CR2: 0000000000000020 CR3: 0000000a7f1bf000 CR4: 00000000000006e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> Process kondemand/0 (pid: 2091, threadinfo ffff880a7d56c000, task
> ffff880a7d4d18c0)
> Stack:
>  ffff880a7f052078 ffffffff803efd54 00000046241a42b6 000000462ffa9e95
>  0000000000000001 0000000000000001 00000000ffffffea ffffffff8064f41a
>  0000000000000012 0000000000000012 ffff880a7f052000 ffffffff80650547
> Call Trace:
>  [<ffffffff803efd54>] ? kobject_get+0x12/0x17
>  [<ffffffff8064f41a>] ? __cpufreq_driver_getavg+0x42/0x57
>  [<ffffffff80650547>] ? do_dbs_timer+0x147/0x272
>  [<ffffffff80650400>] ? do_dbs_timer+0x0/0x272
>  [<ffffffff802474ca>] ? worker_thread+0x15b/0x1f5
>  [<ffffffff8024a02c>] ? autoremove_wake_function+0x0/0x2e
>  [<ffffffff8024736f>] ? worker_thread+0x0/0x1f5
>  [<ffffffff80249f0d>] ? kthread+0x54/0x83
>  [<ffffffff8020c87a>] ? child_rip+0xa/0x20
>  [<ffffffff80249eb9>] ? kthread+0x0/0x83
>  [<ffffffff8020c870>] ? child_rip+0x0/0x20
> Code: 99 a6 03 00 31 c9 85 c0 0f 85 c3 00 00 00 89 df 4c 8b 44 24 10 48
> c7 c2 60 b6 00 00 48 8b 0c fd e0 30 a5 80 4c 89 c3 48 8b 04 0a <48> 2b
> 58 20 48 8b 44 24 18 48 89 1c 24 48 8b 34 0a 48 2b 46 28
> RIP  [<ffffffff8021af75>] get_measured_perf+0x4a/0xf9
>  RSP <ffff880a7d56de20>
> CR2: 0000000000000020
> ---[ end trace 2b8fac9a49e19ad4 ]---
> 
> Reported-by: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com>
> Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
> ---
>  arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c |   15 ++++++++++-----
>  1 files changed, 10 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c b/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c
> index 837c2c4..d722b8d 100644
> --- a/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c
> +++ b/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c
> @@ -68,11 +68,16 @@ struct acpi_cpufreq_data {
>  	unsigned int max_freq;
>  	unsigned int resume;
>  	unsigned int cpu_feature;
> -	u64 saved_aperf, saved_mperf;
>  };
>  
>  static DEFINE_PER_CPU(struct acpi_cpufreq_data *, drv_data);
>  
> +struct acpi_msr_data {
> +	u64 saved_aperf, saved_mperf;
> +};
> +
> +static DEFINE_PER_CPU(struct acpi_msr_data, msr_data);
> +
>  DEFINE_TRACE(power_mark);
>  
>  /* acpi_perf_data is a pointer to percpu data. */
> @@ -281,11 +286,11 @@ static unsigned int get_measured_perf(struct cpufreq_policy *policy,
>  		return 0;
>  
>  	cur.aperf.whole = readin.aperf.whole -
> -				per_cpu(drv_data, cpu)->saved_aperf;
> +				per_cpu(msr_data, cpu).saved_aperf;
>  	cur.mperf.whole = readin.mperf.whole -
> -				per_cpu(drv_data, cpu)->saved_mperf;
> -	per_cpu(drv_data, cpu)->saved_aperf = readin.aperf.whole;
> -	per_cpu(drv_data, cpu)->saved_mperf = readin.mperf.whole;
> +				per_cpu(msr_data, cpu).saved_mperf;
> +	per_cpu(msr_data, cpu).saved_aperf = readin.aperf.whole;
> +	per_cpu(msr_data, cpu).saved_mperf = readin.mperf.whole;
>  
>  #ifdef __i386__
>  	/*