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author | Jiri Slaby <jslaby@suse.cz> | 2011-03-01 16:41:10 (GMT) |
---|---|---|
committer | Dave Jones <davej@redhat.com> | 2011-03-01 23:49:44 (GMT) |
commit | 8f5bc2abfd4240b1f55425a3d36b6e6c391bc148 (patch) | |
tree | 6101e64f0d06ef59c2bd4080f227e1a7db38a5ce /drivers/cpufreq/cpufreq.c | |
parent | a536b126f211bdf9a0eecce0d403a26900d2106c (diff) | |
download | linux-8f5bc2abfd4240b1f55425a3d36b6e6c391bc148.tar.xz |
[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>
Diffstat (limited to 'drivers/cpufreq/cpufreq.c')
-rw-r--r-- | drivers/cpufreq/cpufreq.c | 27 |
1 files changed, 15 insertions, 12 deletions
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 1109f68..5cb4d09 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -1919,8 +1919,10 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data) ret = sysdev_driver_register(&cpu_sysdev_class, &cpufreq_sysdev_driver); + if (ret) + goto err_null_driver; - if ((!ret) && !(cpufreq_driver->flags & CPUFREQ_STICKY)) { + if (!(cpufreq_driver->flags & CPUFREQ_STICKY)) { int i; ret = -ENODEV; @@ -1935,21 +1937,22 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data) if (ret) { dprintk("no CPU initialized for driver %s\n", driver_data->name); - sysdev_driver_unregister(&cpu_sysdev_class, - &cpufreq_sysdev_driver); - - spin_lock_irqsave(&cpufreq_driver_lock, flags); - cpufreq_driver = NULL; - spin_unlock_irqrestore(&cpufreq_driver_lock, flags); + goto err_sysdev_unreg; } } - if (!ret) { - register_hotcpu_notifier(&cpufreq_cpu_notifier); - dprintk("driver %s up and running\n", driver_data->name); - cpufreq_debug_enable_ratelimit(); - } + register_hotcpu_notifier(&cpufreq_cpu_notifier); + dprintk("driver %s up and running\n", driver_data->name); + cpufreq_debug_enable_ratelimit(); + return 0; +err_sysdev_unreg: + sysdev_driver_unregister(&cpu_sysdev_class, + &cpufreq_sysdev_driver); +err_null_driver: + spin_lock_irqsave(&cpufreq_driver_lock, flags); + cpufreq_driver = NULL; + spin_unlock_irqrestore(&cpufreq_driver_lock, flags); return ret; } EXPORT_SYMBOL_GPL(cpufreq_register_driver); |