@@ -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);
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(-)