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authorJiri Slaby <jslaby@suse.cz>2011-03-01 19:41:10 +0300
committerDave Jones <davej@redhat.com>2011-03-02 02:49:44 +0300
commit8f5bc2abfd4240b1f55425a3d36b6e6c391bc148 (patch)
tree6101e64f0d06ef59c2bd4080f227e1a7db38a5ce /drivers/cpufreq/cpufreq.c
parenta536b126f211bdf9a0eecce0d403a26900d2106c (diff)
downloadlinux-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.c27
1 files changed, 15 insertions, 12 deletions
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 1109f6848a43..5cb4d09919d6 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);