diff options
| author | Denis Kirjanov <kda@linux-powerpc.org> | 2016-11-08 05:39:28 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-01-19 20:17:22 +0100 |
| commit | 2c1dd423a5671f6301b583cc0edd0069263c7157 (patch) | |
| tree | d2da849ea04220ddf55091391ed3378e61af10d3 | |
| parent | 33ebdfe913fd6dd3dc8522a6ab4bb5719df5efde (diff) | |
cpufreq: powernv: Disable preemption while checking CPU throttling state
commit 8a10c06a20ec8097a68fd7a4a1c0e285095b4d2f upstream.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/cpufreq/powernv-cpufreq.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c index cb501386eb6e..c4b0ef65988c 100644 --- a/drivers/cpufreq/powernv-cpufreq.c +++ b/drivers/cpufreq/powernv-cpufreq.c @@ -373,8 +373,14 @@ 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(); + } freq_data.pstate_id = powernv_freqs[new_index].driver_data; |