linux-kernel - Re: [PATCH RFC] mailbox: move controller timer to per-channel timers

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Date:   Fri, 7 Apr 2017 20:39:35 +0530
From:   Jassi Brar <jassisinghbrar@...il.com>
To:     Alexey Klimov <alexey.klimov@....com>
Cc:     Sudeep Holla <sudeep.holla@....com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Jassi Brar <jaswinder.singh@...aro.org>
Subject: Re: [PATCH RFC] mailbox: move controller timer to per-channel timers

On Thu, Apr 6, 2017 at 11:01 PM, Alexey Klimov <alexey.klimov@....com> wrote:
> When mailbox controller provides two or more channels and
> they are actively used by mailbox client(s) it's very easy
> to trigger the warning in hrtimer_forward():
>
> [  247.853060] WARNING: CPU: 6 PID: 0 at kernel/time/hrtimer.c:805 hrtimer_forward+0x88/0xd8
> [  247.853549] Modules linked in:
> [  247.853907] CPU: 6 PID: 0 Comm: swapper/6 Tainted: G        W       4.11.0-rc2-00362-g93afaa4513bb-dirty #13
> [  247.854472] Hardware name: linux,dummy-virt (DT)
> [  247.854699] task: ffff80001d89d780 task.stack: ffff80001d8c4000
> [  247.854999] PC is at hrtimer_forward+0x88/0xd8
> [  247.855280] LR is at txdone_hrtimer+0xd4/0xf8
> [  247.855551] pc : [<ffff0000081039f0>] lr : [<ffff00000881b874>] pstate: 200001c5
> [  247.855857] sp : ffff80001efbdeb0
> [  247.856072] x29: ffff80001efbdeb0 x28: ffff80001efc3140
> [  247.856358] x27: ffff00000881b7a0 x26: 00000039ac93e8b6
> [  247.856604] x25: ffff000008e756be x24: ffff80001c4a1348
> [  247.856882] x23: 0000000000000001 x22: 00000000000000f8
> [  247.857189] x21: ffff80001c4a1318 x20: ffff80001d327110
> [  247.857509] x19: 00000000000f4240 x18: 0000000000000030
> [  247.857808] x17: 0000ffffaecdf370 x16: ffff0000081ccc80
> [  247.858000] x15: 0000000000000010 x14: 00000000fffffff0
> [  247.858186] x13: ffff000008f488e0 x12: 000000000002e3eb
> [  247.858381] x11: ffff000008979690 x10: 0000000000000000
> [  247.858573] x9 : 0000000000000001 x8 : ffff80001efc66e0
> [  247.858758] x7 : ffff80001efc6708 x6 : 00000005be7732f2
> [  247.858943] x5 : 0000000000000001 x4 : ffff80001c4a1348
> [  247.859130] x3 : 00000039ac94952a x2 : 00000000000f4240
> [  247.859315] x1 : 00000039ac98243c x0 : 0000000000038f12
> [  247.859582] ---[ end trace d61812426ec3c30b ]---
>
> To fix this current patch migrates hr timers to be per-channel
> instead of using only one timer per-controller.
>
I think we can do by just checking if hrtimer_active() returns false
before we do hrtimer_start() in msg_submit() ?

Thanks.