Messages in this thread | | | Date | Thu, 15 Oct 2020 14:46:28 +0100 | From | Ionela Voinescu <> | Subject | Re: [PATCH] mailbox: cancel timer before starting it |
| |
Hi guys,
On Wednesday 23 Sep 2020 at 14:39:16 (+0200), Jerome Brunet wrote: > If the txdone is done by polling, it is possible for msg_submit() to start > the timer while txdone_hrtimer() callback is running. If the timer needs > recheduling, it could already be enqueued by the time hrtimer_forward_now() > is called, leading hrtimer to loudly complain. > > WARNING: CPU: 3 PID: 74 at kernel/time/hrtimer.c:932 hrtimer_forward+0xc4/0x110 > CPU: 3 PID: 74 Comm: kworker/u8:1 Not tainted 5.9.0-rc2-00236-gd3520067d01c-dirty #5 > Hardware name: Libre Computer AML-S805X-AC (DT) > Workqueue: events_freezable_power_ thermal_zone_device_check > pstate: 20000085 (nzCv daIf -PAN -UAO BTYPE=--) > pc : hrtimer_forward+0xc4/0x110 > lr : txdone_hrtimer+0xf8/0x118 > [...] > > Canceling the timer before starting it ensure that the timer callback is > not running when the timer is started, solving this race condition. > > Fixes: 0cc67945ea59 ("mailbox: switch to hrtimer for tx_complete polling") > Reported-by: Da Xue <da@libre.computer> > Signed-off-by: Jerome Brunet <jbrunet@baylibre.com> > --- > drivers/mailbox/mailbox.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c > index 0b821a5b2db8..34f9ab01caef 100644 > --- a/drivers/mailbox/mailbox.c > +++ b/drivers/mailbox/mailbox.c > @@ -82,9 +82,13 @@ static void msg_submit(struct mbox_chan *chan) > exit: > spin_unlock_irqrestore(&chan->lock, flags); > > - if (!err && (chan->txdone_method & TXDONE_BY_POLL)) > - /* kick start the timer immediately to avoid delays */ > + if (!err && (chan->txdone_method & TXDONE_BY_POLL)) { > + /* Disable the timer if already active ... */ > + hrtimer_cancel(&chan->mbox->poll_hrt); > + > + /* ... and kick start it immediately to avoid delays */ > hrtimer_start(&chan->mbox->poll_hrt, 0, HRTIMER_MODE_REL); > + } > } > > static void tx_tick(struct mbox_chan *chan, int r)
I've tracked a regression back to this commit. Details to reproduce:
- HEAD: (linux-next) * 62c04453381e Jerome Brunet 3 weeks ago mailbox: cancel timer before starting it
- Platform: arm64 Juno R0 and Juno R2 [1]
- Partial log: [ 0.000000] Booting Linux on physical CPU 0x0000000100 [0x410fd030] [ 0.000000] Linux version 5.9.0-rc8-01722-g62c04453381e () (aarch64-none-linux-gnu-gcc (GNU Toolchain for the A-profile Architecture 9.2-2019.12 (arm-9.10)) 9.2.1 20191025, GNU ld (GNU Toolchain for the A-profile Architecture 9.2-2019.12 (arm-9.10)) 2.33.1.20191209) #175 SMP PREEMPT Thu Oct 15 14:17:41 BST 2020 [ 0.000000] Machine model: ARM Juno development board (r0) [..] [ 1.714340] mhu 2b1f0000.mhu: ARM MHU Mailbox registered [ 1.722768] NET: Registered protocol family 17 [ 1.727364] 9pnet: Installing 9P2000 support [ 1.731689] Key type dns_resolver registered [ 1.735474] usb 1-1: new high-speed USB device number 2 using ehci-platform [ 1.736407] registered taskstats version 1 [ 1.747061] Loading compiled-in X.509 certificates [ 1.755885] scpi_protocol scpi: SCP Protocol 1.2 Firmware 1.21.0 version [ 1.770484] cpu cpu0: EM: created perf domain [ 1.778505] cpu cpu1: EM: created perf domain [ 1.807449] scpi_clocks scpi:clocks: failed to register clock 'pxlclk' [ 1.897593] hub 1-1:1.0: USB hub found [ 1.901656] hub 1-1:1.0: 4 ports detected [ 2.559453] atkbd serio0: keyboard reset failed on 1c060000.kmi [ 22.787431] rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: [ 22.793536] rcu: 1-...0: (1 ticks this GP) idle=222/1/0x4000000000000002 softirq=63/64 fqs=2626 [ 22.802421] (detected by 2, t=5255 jiffies, g=-991, q=9) [ 22.807823] Task dump for CPU 1: [ 22.811049] task:swapper/1 state:R running task stack: 0 pid: 0 ppid: 1 flags:0x0000002a [ 22.820980] Call trace: [ 22.823429] __switch_to+0x138/0x198 [ 23.583444] rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 1-... } 5443 jiffies s: 49 root: 0x2/. [ 23.593995] rcu: blocking rcu_node structures: [ 23.598449] Task dump for CPU 1: [ 23.601680] task:swapper/1 state:R running task stack: 0 pid: 0 ppid: 1 flags:0x0000002a [ 23.611619] Call trace: [ 23.614064] __switch_to+0x138/0x198 [ 85.807430] rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: [ 85.813534] rcu: 1-...0: (1 ticks this GP) idle=222/1/0x4000000000000002 softirq=63/64 fqs=10502 [ 85.822506] (detected by 2, t=21009 jiffies, g=-991, q=9) [ 85.827994] Task dump for CPU 1: [ 85.831220] task:swapper/1 state:R running task stack: 0 pid: 0 ppid: 1 flags:0x0000002a [ 85.841150] Call trace: [ 85.843596] __switch_to+0x138/0x198 [ 87.071446] rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 1-... } 21315 jiffies s: 49 root: 0x2/. [ 87.082088] rcu: blocking rcu_node structures: [ 87.086540] Task dump for CPU 1: [ 87.089773] task:swapper/1 state:R running task stack: 0 pid: 0 ppid: 1 flags:0x0000002a [ 87.099708] Call trace: [ 87.102155] __switch_to+0x138/0x198 [ 148.827442] rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: [ 148.833565] rcu: 1-...0: (1 ticks this GP) idle=222/1/0x4000000000000002 softirq=63/64 fqs=18377 [ 148.842543] (detected by 4, t=36762 jiffies, g=-991, q=9) [ 148.848037] Task dump for CPU 1: [ 148.851268] task:swapper/1 state:R running task stack: 0 pid: 0 ppid: 1 flags:0x0000002a [ 148.861207] Call trace: [ 148.863663] __switch_to+0x138/0x198 [ 150.559443] rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 1-... } 37187 jiffies s: 49 root: 0x2/. [ 150.570082] rcu: blocking rcu_node structures: [ 150.574535] Task dump for CPU 1: [ 150.577767] task:swapper/1 state:R running task stack: 0 pid: 0 ppid: 1 flags:0x0000002a [ 150.587705] Call trace: [ 150.590151] __switch_to+0x138/0x198
- Commit working as expected: * 558e4c36ec9f Krzysztof Kozlowski 7 weeks ago maiblox: mediatek: Fix handling of platform_get_irq() error
[1] https://developer.arm.com/tools-and-software/development-boards/juno-development-board
Thank you, Ionela.
> -- > 2.25.4 > > > _______________________________________________ > linux-amlogic mailing list > linux-amlogic@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-amlogic
| |