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authorDenis Kirjanov <kda@linux-powerpc.org>2016-11-08 05:39:28 -0500
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2016-11-16 23:29:59 +0100
commit8a10c06a20ec8097a68fd7a4a1c0e285095b4d2f (patch)
treee2c0a41a2692ac31f2840d8d00697c4a9a3b80cc /drivers/cpufreq/powernv-cpufreq.c
parent42d951c851f1d08bb12430a7e2e9f4657f7c395c (diff)
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cpufreq: powernv: Disable preemption while checking CPU throttling state
With preemption turned on we can read incorrect throttling state while being switched to CPU on a different chip. BUG: using smp_processor_id() in preemptible [00000000] code: cat/7343 caller is .powernv_cpufreq_throttle_check+0x2c/0x710 CPU: 13 PID: 7343 Comm: cat Not tainted 4.8.0-rc5-dirty #1 Call Trace: [c0000007d25b75b0] [c000000000971378] .dump_stack+0xe4/0x150 (unreliable) [c0000007d25b7640] [c0000000005162e4] .check_preemption_disabled+0x134/0x150 [c0000007d25b76e0] [c0000000007b63ac] .powernv_cpufreq_throttle_check+0x2c/0x710 [c0000007d25b7790] [c0000000007b6d18] .powernv_cpufreq_target_index+0x288/0x360 [c0000007d25b7870] [c0000000007acee4] .__cpufreq_driver_target+0x394/0x8c0 [c0000007d25b7920] [c0000000007b22ac] .cpufreq_set+0x7c/0xd0 [c0000007d25b79b0] [c0000000007adf50] .store_scaling_setspeed+0x80/0xc0 [c0000007d25b7a40] [c0000000007ae270] .store+0xa0/0x100 [c0000007d25b7ae0] [c0000000003566e8] .sysfs_kf_write+0x88/0xb0 [c0000007d25b7b70] [c0000000003553b8] .kernfs_fop_write+0x178/0x260 [c0000007d25b7c10] [c0000000002ac3cc] .__vfs_write+0x3c/0x1c0 [c0000007d25b7cf0] [c0000000002ad584] .vfs_write+0xc4/0x230 [c0000007d25b7d90] [c0000000002aeef8] .SyS_write+0x58/0x100 [c0000007d25b7e30] [c00000000000bfec] system_call+0x38/0xfc Fixes: 09a972d16209 (cpufreq: powernv: Report cpu frequency throttling) Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com> Signed-off-by: Denis Kirjanov <kda@linux-powerpc.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/cpufreq/powernv-cpufreq.c')
-rw-r--r--drivers/cpufreq/powernv-cpufreq.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c
index c5c5bc35eece..37671b545880 100644
--- a/drivers/cpufreq/powernv-cpufreq.c
+++ b/drivers/cpufreq/powernv-cpufreq.c
@@ -664,8 +664,14 @@ static int powernv_cpufreq_target_index(struct cpufreq_policy *policy,
if (unlikely(rebooting) && new_index != get_nominal_index())
return 0;
- if (!throttled)
+ if (!throttled) {
+ /* we don't want to be preempted while
+ * checking if the CPU frequency has been throttled
+ */
+ preempt_disable();
powernv_cpufreq_throttle_check(NULL);
+ preempt_enable();
+ }
cur_msec = jiffies_to_msecs(get_jiffies_64());
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