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SubjectRe: ALSA: intel8x0: div by zero in snd_intel8x0_update()
On Fri, 14 May 2021 10:17:10 +0200,
Sergey Senozhatsky wrote:
>
> Hi,
>
> I'm running (sometimes) into the following problem during resume
>
> divide error: 0000 [#1] PREEMPT SMP NOPTI
> RIP: 0010:snd_intel8x0_interrupt+0x121/0x279
> Code: 42 8b 44 35 34 41 0f af c5 42 03 44 35 38 42 89 44 35 38 48 8b 0c 24 80 b9 60 03 00 00 00 78 0f 49 8d 0c 2e 48 83 c1 38 31 d2 <f7> 71 f4 89 11 42 8b 7c 35 48 44 01 ef 83 e7 1f 42 89 7c 35 48 48
> RSP: 0000:ffff9a0a80108eb0 EFLAGS: 00010046
> RAX: 0000000000000000 RBX: 0000000000000019 RCX: ffff90d8c5efc198
> RDX: 0000000000000000 RSI: ffff9a0a80549016 RDI: ffff9a0a80549024
> RBP: ffff90d8c5efc060 R08: 000000000000197a R09: 00000f604ed00191
> R10: 00000000000001e0 R11: ffffffff9468e1d8 R12: 0000000000000020
> R13: 0000000000000040 R14: 0000000000000100 R15: 0000000000000002
> FS: 00007a75c397aff8(0000) GS:ffff90d912d80000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007a77945d1000 CR3: 000000015bf46002 CR4: 0000000000360ea0
> Call Trace:
> <IRQ>
> __handle_irq_event_percpu+0xa0/0x1c0
> handle_irq_event_percpu+0x2d/0x70
> handle_irq_event+0x2c/0x48
> handle_fasteoi_irq+0xa1/0x161
> do_IRQ+0x51/0xd6
> common_interrupt+0xf/0xf
> </IRQ>
> RIP: 0033:0x7a7856462c59
> Code: 89 ca 48 2b 57 20 48 83 c2 10 31 c0 48 3b 57 28 48 0f 46 c1 c3 cc cc cc cc cc cc cc cc cc cc cc cc 64 48 8b 0c 25 00 00 00 00 <b8> f8 02 00 00 48 03 41 08 c3 cc cc cc cc cc cc cc cc cc cc cc cc
> RSP: 002b:00007a75c39794e8 EFLAGS: 00000246 ORIG_RAX: ffffffffffffffde
> RAX: 02fa413b24209c6c RBX: 0000017f19e1cf9e RCX: 00007a75c397aff8
> RDX: 00007a7855792472 RSI: 00007a7855790aa0 RDI: 0000000000000005
> RBP: 0000000000000005 R08: 0000000000000012 R09: 000000000000000d
> R10: 00000000009f86d2 R11: 000000000000197a R12: 0000017f19e40e7d
> R13: 000005ee937ae557 R14: 00007a7855790aa0 R15: 00007a7855792472
> Modules linked in:
> ---[ end trace 2ef6d63d0e3d757c ]---
> RIP: 0010:snd_intel8x0_interrupt+0x121/0x279
> Code: 42 8b 44 35 34 41 0f af c5 42 03 44 35 38 42 89 44 35 38 48 8b 0c 24 80 b9 60 03 00 00 00 78 0f 49 8d 0c 2e 48 83 c1 38 31 d2 <f7> 71 f4 89 11 42 8b 7c 35 48 44 01 ef 83 e7 1f 42 89 7c 35 48 48
> RSP: 0000:ffff9a0a80108eb0 EFLAGS: 00010046
> RAX: 0000000000000000 RBX: 0000000000000019 RCX: ffff90d8c5efc198
> RDX: 0000000000000000 RSI: ffff9a0a80549016 RDI: ffff9a0a80549024
> RBP: ffff90d8c5efc060 R08: 000000000000197a R09: 00000f604ed00191
> R10: 00000000000001e0 R11: ffffffff9468e1d8 R12: 0000000000000020
> R13: 0000000000000040 R14: 0000000000000100 R15: 0000000000000002
> FS: 00007a75c397aff8(0000) GS:ffff90d912d80000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007a77945d1000 CR3: 000000015bf46002 CR4: 0000000000360ea0
>
> This corresponds to
>
> ichdev->position %= ichdev->size;
>
> in snd_intel8x0_update().
>
> A print out of that ichdev looks as follows
>
> snd_intel8x0 0000:00:18.0: lvi_frag = 0, frags = 0, size = 0, period_size = 0x0, period_size1 = 0x0

This sounds like some spurious IRQ that casually hits during the
resume. It's strange that, even if it's a spurious IRQ, it contains
the proper update bits for the stream. Is that on a real hardware or
on a VM?

In anyway, the patch like below might cover enough.


Takashi

--- a/sound/pci/intel8x0.c
+++ b/sound/pci/intel8x0.c
@@ -691,6 +691,9 @@ static inline void snd_intel8x0_update(struct intel8x0 *chip, struct ichdev *ich
int status, civ, i, step;
int ack = 0;

+ if (!ichdev->substream || ichdev->suspended)
+ return;
+
spin_lock_irqsave(&chip->reg_lock, flags);
status = igetbyte(chip, port + ichdev->roff_sr);
civ = igetbyte(chip, port + ICH_REG_OFF_CIV);
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