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Pallipadi, Venkatesh 093f13e231 x86, acpi_cpufreq: Fix the NULL pointer dereference in get_measured_perf 
Fix for a regression that was introduced by earlier commit
18b2646fe3 on Mon Apr 6 11:26:08 2009

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 ]---

Tested-by: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com>
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
2009-04-19 22:47:20 -04:00
..
alpha Merge branch 'tracing-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-04-05 11:04:19 -07:00
arm Merge branch 'defconfig-s3c2410' of git://aeryn.fluff.org.uk/bjdooks/linux 2009-04-17 21:35:56 +01:00
avr32 dma-mapping: replace all DMA_32BIT_MASK macro with DMA_BIT_MASK(32) 2009-04-07 08:31:11 -07:00
blackfin tty: Blackin CTS/RTS 2009-04-07 08:44:05 -07:00
cris tty: Use the generic RS485 ioctl on CRIS 2009-04-07 08:44:05 -07:00
frv FRV: Move to arch/frv/include/asm/ 2009-04-10 01:48:06 +01:00
h8300 Get rid of final remnants of include/asm-$(ARCH) 2009-04-17 09:59:27 -07:00
ia64 Replace all DMA_nBIT_MASK macro with DMA_BIT_MASK(n) 2009-04-13 15:04:33 -07:00
m32r m32r: move include/asm-m32r/* to arch/m32r/include/asm/ 2009-04-17 10:50:23 +09:00
m68k Merge branch 'tracing-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-04-05 11:04:19 -07:00
m68knommu Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gerg/m68knommu 2009-04-03 09:44:58 -07:00
microblaze microblaze: remove duplicated #include's 2009-04-14 11:09:15 +02:00
mips Merge branch 'next' into for-linus 2009-04-08 00:00:33 -07:00
mn10300 MN10300: Stop gcc from generating uninitialised variable warnings after BUG() 2009-04-15 13:55:13 -07:00
parisc Merge git://git.kernel.org/pub/scm/linux/kernel/git/kyle/parisc-2.6 2009-04-03 09:52:04 -07:00
powerpc Merge branch 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc 2009-04-15 08:42:40 -07:00
s390 [S390] boot cputime accounting 2009-04-14 15:37:27 +02:00
sh sh: Add in PCI bus for DMA API debugging. 2009-04-14 15:23:40 +09:00
sparc sparc: remove some pointless conditionals before kfree() 2009-04-15 03:04:56 -07:00
um Merge branch 'tracing-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-04-05 11:04:19 -07:00
x86 x86, acpi_cpufreq: Fix the NULL pointer dereference in get_measured_perf 2009-04-19 22:47:20 -04:00
xtensa Merge branch 'tracing-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-04-05 11:04:19 -07:00
.gitignore
Kconfig mutex: have non-spinning mutexes on s390 by default 2009-04-09 19:28:24 +02:00