linux/drivers/cpufreq
Jiri Slaby 8f5bc2abfd [CPUFREQ] fix BUG on cpufreq policy init failure
cpufreq_register_driver sets cpufreq_driver to a structure owned (and
placed) in the caller's memory. If cpufreq policy fails in its ->init
function, sysdev_driver_register returns nonzero in
cpufreq_register_driver. Now, cpufreq_register_driver returns an error
without setting cpufreq_driver back to NULL.

Usually cpufreq policy modules are unloaded because they propagate the
error to the module init function and return that.

So a later access to any member of cpufreq_driver causes bugs like:
BUG: unable to handle kernel paging request at ffffffffa00270a0
IP: [<ffffffff8145eca3>] cpufreq_cpu_get+0x53/0xe0
PGD 1805067 PUD 1809063 PMD 1c3f90067 PTE 0
Oops: 0000 [#1] SMP
last sysfs file: /sys/devices/virtual/net/tun0/statistics/collisions
CPU 0
Modules linked in: ...
Pid: 5677, comm: thunderbird-bin Tainted: G        W   2.6.38-rc4-mm1_64+ #1389 To be filled by O.E.M./To Be Filled By O.E.M.
RIP: 0010:[<ffffffff8145eca3>]  [<ffffffff8145eca3>] cpufreq_cpu_get+0x53/0xe0
RSP: 0018:ffff8801aec37d98  EFLAGS: 00010086
RAX: 0000000000000202 RBX: 0000000000000000 RCX: 0000000000000001
RDX: ffffffffa00270a0 RSI: 0000000000001000 RDI: ffffffff8199ece8
...
Call Trace:
 [<ffffffff8145f490>] cpufreq_quick_get+0x10/0x30
 [<ffffffff8103f12b>] show_cpuinfo+0x2ab/0x300
 [<ffffffff81136292>] seq_read+0xf2/0x3f0
 [<ffffffff8126c5d3>] ? __strncpy_from_user+0x33/0x60
 [<ffffffff8116850d>] proc_reg_read+0x6d/0xa0
 [<ffffffff81116e53>] vfs_read+0xc3/0x180
 [<ffffffff81116f5c>] sys_read+0x4c/0x90
 [<ffffffff81030dbb>] system_call_fastpath+0x16/0x1b
...

It's all cause by weird fail path handling in cpufreq_register_driver.
To fix that, shuffle the code to do proper handling with gotos.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Dave Jones <davej@redhat.com>
2011-03-01 18:49:44 -05:00
..
Kconfig kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
Makefile [CPUFREQ] Conservative cpufreq governer 2005-05-31 19:03:47 -07:00
cpufreq.c [CPUFREQ] fix BUG on cpufreq policy init failure 2011-03-01 18:49:44 -05:00
cpufreq_conservative.c Merge commit 'v2.6.34-rc6' into x86/cpu 2010-05-08 14:59:58 -07:00
cpufreq_ondemand.c [CPUFREQ] add sampling_down_factor tunable to improve ondemand performance 2010-10-22 11:44:47 -04:00
cpufreq_performance.c [CPUFREQ] Don't export governors for default governor 2008-10-09 13:52:44 -04:00
cpufreq_powersave.c [CPUFREQ] Don't export governors for default governor 2008-10-09 13:52:44 -04:00
cpufreq_stats.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
cpufreq_userspace.c [CPUFREQ] checkpatch cleanups for userspace governor 2009-02-24 22:47:30 -05:00
freq_table.c percpu: make percpu symbols in cpufreq unique 2009-10-29 22:34:13 +09:00