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authorPrarit Bhargava <prarit@redhat.com>2014-09-10 10:12:08 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-10-05 14:52:22 -0700
commitc9bf87daad34a80e4f742a94238cf8449e444add (patch)
tree1573968b9f3579de4dc7ea54cfbc8b73a5462c7d /drivers/cpufreq
parent65439f28c296101cb38c33a8266ad5ca58f7c5b9 (diff)
cpufreq: release policy->rwsem on error
commit 7106e02baed4a72fb23de56b02ad4d31daa74d95 upstream. While debugging a cpufreq-related hardware failure on a system I saw the following lockdep warning: ========================= [ BUG: held lock freed! ] 3.17.0-rc4+ #1 Tainted: G E ------------------------- insmod/2247 is freeing memory ffff88006e1b1400-ffff88006e1b17ff, with a lock still held there! (&policy->rwsem){+.+...}, at: [<ffffffff8156d37d>] __cpufreq_add_dev.isra.21+0x47d/0xb80 3 locks held by insmod/2247: #0: (subsys mutex#5){+.+.+.}, at: [<ffffffff81485579>] subsys_interface_register+0x69/0x120 #1: (cpufreq_rwsem){.+.+.+}, at: [<ffffffff8156cf73>] __cpufreq_add_dev.isra.21+0x73/0xb80 #2: (&policy->rwsem){+.+...}, at: [<ffffffff8156d37d>] __cpufreq_add_dev.isra.21+0x47d/0xb80 stack backtrace: CPU: 0 PID: 2247 Comm: insmod Tainted: G E 3.17.0-rc4+ #1 Hardware name: HP ProLiant MicroServer Gen8, BIOS J06 08/24/2013 0000000000000000 000000008f3063c4 ffff88006f87bb30 ffffffff8171b358 ffff88006bcf3750 ffff88006f87bb68 ffffffff810e09e1 ffff88006e1b1400 ffffea0001b86c00 ffffffff8156d327 ffff880073003500 0000000000000246 Call Trace: [<ffffffff8171b358>] dump_stack+0x4d/0x66 [<ffffffff810e09e1>] debug_check_no_locks_freed+0x171/0x180 [<ffffffff8156d327>] ? __cpufreq_add_dev.isra.21+0x427/0xb80 [<ffffffff8121412b>] kfree+0xab/0x2b0 [<ffffffff8156d327>] __cpufreq_add_dev.isra.21+0x427/0xb80 [<ffffffff81724cf7>] ? _raw_spin_unlock+0x27/0x40 [<ffffffffa003517f>] ? pcc_cpufreq_do_osc+0x17f/0x17f [pcc_cpufreq] [<ffffffff8156da8e>] cpufreq_add_dev+0xe/0x10 [<ffffffff814855d1>] subsys_interface_register+0xc1/0x120 [<ffffffff8156bcf2>] cpufreq_register_driver+0x112/0x340 [<ffffffff8121415a>] ? kfree+0xda/0x2b0 [<ffffffffa003517f>] ? pcc_cpufreq_do_osc+0x17f/0x17f [pcc_cpufreq] [<ffffffffa003562e>] pcc_cpufreq_init+0x4af/0xe81 [pcc_cpufreq] [<ffffffffa003517f>] ? pcc_cpufreq_do_osc+0x17f/0x17f [pcc_cpufreq] [<ffffffff81002144>] do_one_initcall+0xd4/0x210 [<ffffffff811f7472>] ? __vunmap+0xd2/0x120 [<ffffffff81127155>] load_module+0x1315/0x1b70 [<ffffffff811222a0>] ? store_uevent+0x70/0x70 [<ffffffff811229d9>] ? copy_module_from_fd.isra.44+0x129/0x180 [<ffffffff81127b86>] SyS_finit_module+0xa6/0xd0 [<ffffffff81725b69>] system_call_fastpath+0x16/0x1b cpufreq: __cpufreq_add_dev: ->get() failed insmod: ERROR: could not insert module pcc-cpufreq.ko: No such device The warning occurs in the __cpufreq_add_dev() code which does down_write(&policy->rwsem); ... if (cpufreq_driver->get && !cpufreq_driver->setpolicy) { policy->cur = cpufreq_driver->get(policy->cpu); if (!policy->cur) { pr_err("%s: ->get() failed\n", __func__); goto err_get_freq; } If cpufreq_driver->get(policy->cpu) returns an error we execute the code at err_get_freq, which does not up the policy->rwsem. This causes the lockdep warning. Trivial patch to up the policy->rwsem in the error path. After the patch has been applied, and an error occurs in the cpufreq_driver->get(policy->cpu) call we will now see cpufreq: __cpufreq_add_dev: ->get() failed cpufreq: __cpufreq_add_dev: ->get() failed modprobe: ERROR: could not insert 'pcc_cpufreq': No such device Fixes: 4e97b631f24c (cpufreq: Initialize governor for a new policy under policy->rwsem) Signed-off-by: Prarit Bhargava <prarit@redhat.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/cpufreq')
-rw-r--r--drivers/cpufreq/cpufreq.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 153f4b92cc05..415923606164 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1225,6 +1225,8 @@ err_get_freq:
per_cpu(cpufreq_cpu_data, j) = NULL;
write_unlock_irqrestore(&cpufreq_driver_lock, flags);
+ up_write(&policy->rwsem);
+
if (cpufreq_driver->exit)
cpufreq_driver->exit(policy);
err_set_policy_cpu: