diff mbox series

PM / devfreq: Synchronize queuing the same timer instance twice

Message ID 1699957648-31299-1-git-send-email-quic_mojha@quicinc.com
State New
Headers show
Series PM / devfreq: Synchronize queuing the same timer instance twice | expand

Commit Message

Mukesh Ojha Nov. 14, 2023, 10:27 a.m. UTC
There is a chance if a frequent switch of the governor
done in a loop result in timer list corruption where
timer_cancel being done from two place one from
cancel_delayed_work_sync() and followed by expire_timers()
can be seen from the traces[1], however, looks like
device_monitor_[start/stop] need to synchronized too.

Let's use polling flag to synchronize the queueing the
timer instance twice.

[1]
...
..
<idle>-0    [003]   9436.209662:  timer_cancel   timer=0xffffff80444f0428
<idle>-0    [003]   9436.209664:  timer_expire_entry   timer=0xffffff80444f0428  now=0x10022da1c  function=__typeid__ZTSFvP10timer_listE_global_addr  baseclk=0x10022da1c
<idle>-0    [003]   9436.209718:  timer_expire_exit   timer=0xffffff80444f0428
kworker/u16:6-14217    [003]   9436.209863:  timer_start   timer=0xffffff80444f0428  function=__typeid__ZTSFvP10timer_listE_global_addr  expires=0x10022da2b  now=0x10022da1c  flags=182452227
vendor.xxxyyy.ha-1593    [004]   9436.209888:  timer_cancel   timer=0xffffff80444f0428
vendor.xxxyyy.ha-1593    [004]   9436.216390:  timer_init   timer=0xffffff80444f0428
vendor.xxxyyy.ha-1593    [004]   9436.216392:  timer_start   timer=0xffffff80444f0428  function=__typeid__ZTSFvP10timer_listE_global_addr  expires=0x10022da2c  now=0x10022da1d  flags=186646532
vendor.xxxyyy.ha-1593    [005]   9436.220992:  timer_cancel   timer=0xffffff80444f0428
xxxyyyTraceManag-7795    [004]   9436.261641:  timer_cancel   timer=0xffffff80444f0428

[2]

 9436.261653][    C4] Unable to handle kernel paging request at virtual address dead00000000012a
[ 9436.261664][    C4] Mem abort info:
[ 9436.261666][    C4]   ESR = 0x96000044
[ 9436.261669][    C4]   EC = 0x25: DABT (current EL), IL = 32 bits
[ 9436.261671][    C4]   SET = 0, FnV = 0
[ 9436.261673][    C4]   EA = 0, S1PTW = 0
[ 9436.261675][    C4] Data abort info:
[ 9436.261677][    C4]   ISV = 0, ISS = 0x00000044
[ 9436.261680][    C4]   CM = 0, WnR = 1
[ 9436.261682][    C4] [dead00000000012a] address between user and kernel address ranges
[ 9436.261685][    C4] Internal error: Oops: 96000044 [#1] PREEMPT SMP
[ 9436.261701][    C4] Skip md ftrace buffer dump for: 0x3a982d0
...

[ 9436.262138][    C4] CPU: 4 PID: 7795 Comm: TraceManag Tainted: G S      W  O      5.10.149-android12-9-o-g17f915d29d0c #1
[ 9436.262141][    C4] Hardware name: Qualcomm Technologies, Inc.  (DT)
[ 9436.262144][    C4] pstate: 22400085 (nzCv daIf +PAN -UAO +TCO BTYPE=--)
[ 9436.262161][    C4] pc : expire_timers+0x9c/0x438
[ 9436.262164][    C4] lr : expire_timers+0x2a4/0x438
[ 9436.262168][    C4] sp : ffffffc010023dd0
[ 9436.262171][    C4] x29: ffffffc010023df0 x28: ffffffd0636fdc18
[ 9436.262178][    C4] x27: ffffffd063569dd0 x26: ffffffd063536008
[ 9436.262182][    C4] x25: 0000000000000001 x24: ffffff88f7c69280
[ 9436.262185][    C4] x23: 00000000000000e0 x22: dead000000000122
[ 9436.262188][    C4] x21: 000000010022da29 x20: ffffff8af72b4e80
[ 9436.262191][    C4] x19: ffffffc010023e50 x18: ffffffc010025038
[ 9436.262195][    C4] x17: 0000000000000240 x16: 0000000000000201
[ 9436.262199][    C4] x15: ffffffffffffffff x14: ffffff889f3c3100
[ 9436.262203][    C4] x13: ffffff889f3c3100 x12: 00000000049f56b8
[ 9436.262207][    C4] x11: 00000000049f56b8 x10: 00000000ffffffff
[ 9436.262212][    C4] x9 : ffffffc010023e50 x8 : dead000000000122
[ 9436.262216][    C4] x7 : ffffffffffffffff x6 : ffffffc0100239d8
[ 9436.262220][    C4] x5 : 0000000000000000 x4 : 0000000000000101
[ 9436.262223][    C4] x3 : 0000000000000080 x2 : ffffff889edc155c
[ 9436.262227][    C4] x1 : ffffff8001005200 x0 : ffffff80444f0428
[ 9436.262232][    C4] Call trace:
[ 9436.262236][    C4]  expire_timers+0x9c/0x438
[ 9436.262240][    C4]  __run_timers+0x1f0/0x330
[ 9436.262245][    C4]  run_timer_softirq+0x28/0x58
[ 9436.262255][    C4]  efi_header_end+0x168/0x5ec
[ 9436.262265][    C4]  __irq_exit_rcu+0x108/0x124
[ 9436.262274][    C4]  __handle_domain_irq+0x118/0x1e4
[ 9436.262282][    C4]  gic_handle_irq.30369+0x6c/0x2bc
[ 9436.262286][    C4]  el0_irq_naked+0x60/0x6c

Signed-off-by: Mukesh Ojha <quic_mojha@quicinc.com>
---
This is further to the issue reported at 

https://lore.kernel.org/all/1699459797-21703-1-git-send-email-quic_mojha@quicinc.com/


 drivers/devfreq/devfreq.c | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 474d81831ad3..09b93104521b 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -461,10 +461,14 @@  static void devfreq_monitor(struct work_struct *work)
 	if (err)
 		dev_err(&devfreq->dev, "dvfs failed with (%d) error\n", err);
 
+	if (devfreq->stop_polling)
+		goto out;
+
 	queue_delayed_work(devfreq_wq, &devfreq->work,
 				msecs_to_jiffies(devfreq->profile->polling_ms));
-	mutex_unlock(&devfreq->lock);
 
+out:
+	mutex_unlock(&devfreq->lock);
 	trace_devfreq_monitor(devfreq);
 }
 
@@ -483,6 +487,7 @@  void devfreq_monitor_start(struct devfreq *devfreq)
 	if (IS_SUPPORTED_FLAG(devfreq->governor->flags, IRQ_DRIVEN))
 		return;
 
+	mutex_lock(&devfreq->lock);
 	switch (devfreq->profile->timer) {
 	case DEVFREQ_TIMER_DEFERRABLE:
 		INIT_DEFERRABLE_WORK(&devfreq->work, devfreq_monitor);
@@ -491,12 +496,16 @@  void devfreq_monitor_start(struct devfreq *devfreq)
 		INIT_DELAYED_WORK(&devfreq->work, devfreq_monitor);
 		break;
 	default:
-		return;
+		goto out;
 	}
 
 	if (devfreq->profile->polling_ms)
 		queue_delayed_work(devfreq_wq, &devfreq->work,
 			msecs_to_jiffies(devfreq->profile->polling_ms));
+
+	devfreq->stop_polling = false;
+out:
+	mutex_unlock(&devfreq->lock);
 }
 EXPORT_SYMBOL(devfreq_monitor_start);
 
@@ -513,6 +522,14 @@  void devfreq_monitor_stop(struct devfreq *devfreq)
 	if (IS_SUPPORTED_FLAG(devfreq->governor->flags, IRQ_DRIVEN))
 		return;
 
+	mutex_lock(&devfreq->lock);
+	if (devfreq->stop_polling) {
+		mutex_unlock(&devfreq->lock);
+		return;
+	}
+
+	devfreq->stop_polling = true;
+	mutex_unlock(&devfreq->lock);
 	cancel_delayed_work_sync(&devfreq->work);
 }
 EXPORT_SYMBOL(devfreq_monitor_stop);