linux-kernel - Re: [PATCH] remoteproc: k3-r5: Fix driver shutdown

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Message-ID: <9ce9044c-085f-4eff-b142-ab36d39d90b4@siemens.com>
Date: Tue, 20 Aug 2024 11:39:06 +0200
From: Jan Kiszka <jan.kiszka@...mens.com>
To: Beleswar Prasad Padhi <b-padhi@...com>,
 Bjorn Andersson <andersson@...nel.org>,
 Mathieu Poirier <mathieu.poirier@...aro.org>,
 linux-remoteproc@...r.kernel.org
Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
 Apurva Nandan <a-nandan@...com>,
 "stable@...r.kernel.org" <stable@...r.kernel.org>, Nishanth Menon <nm@...com>
Subject: Re: [PATCH] remoteproc: k3-r5: Fix driver shutdown

On 20.08.24 11:30, Beleswar Prasad Padhi wrote:
> Hi Jan,
> 
> On 19-08-2024 22:17, Jan Kiszka wrote:
>> From: Jan Kiszka <jan.kiszka@...mens.com>
>>
>> When k3_r5_cluster_rproc_exit is run, core 1 is shutdown and removed
>> first. When core 0 should then be stopped before its removal, it will
>> find core1->rproc as NULL already and crashes. Happens on rmmod e.g.
> 
> 
> Did you check this on top of -next-20240820 tag? There was a series[0]
> which was merged recently which fixed this condition. I don't see this
> issue when trying on top of -next-20240820 tag.
> [0]: https://lore.kernel.org/all/20240808074127.2688131-1-b-padhi@ti.com/
> 

I didn't try those yet, I was on 6.11-rcX. But from reading them
quickly, I'm not seeing the two issues I found directly addressed there.

>>
>> Fixes: 3c8a9066d584 ("remoteproc: k3-r5: Do not allow core1 to power
>> up before core0 via sysfs")
>> CC: stable@...r.kernel.org
>> Signed-off-by: Jan Kiszka <jan.kiszka@...mens.com>
>> ---
>>
>> There might be one more because I can still make this driver crash
>> after an operator error. Were error scenarios tested at all?
> 
> 
> Can you point out what is this issue more specifically, and I can take
> this up then.

Try starting core1 before core0, and then again - system will hang or
crash while trying to wipe ATCM. I do not understand this problem yet -
same VA is used, and I cannot see where/how the region should have been
unmapped in between.

Jan

> 
>>
>>   drivers/remoteproc/ti_k3_r5_remoteproc.c | 3 ++-
>>   1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/remoteproc/ti_k3_r5_remoteproc.c
>> b/drivers/remoteproc/ti_k3_r5_remoteproc.c
>> index eb09d2e9b32a..9ebd7a34e638 100644
>> --- a/drivers/remoteproc/ti_k3_r5_remoteproc.c
>> +++ b/drivers/remoteproc/ti_k3_r5_remoteproc.c
>> @@ -646,7 +646,8 @@ static int k3_r5_rproc_stop(struct rproc *rproc)
>>           /* do not allow core 0 to stop before core 1 */
>>           core1 = list_last_entry(&cluster->cores, struct k3_r5_core,
>>                       elem);
>> -        if (core != core1 && core1->rproc->state != RPROC_OFFLINE) {
>> +        if (core != core1 && core1->rproc &&
>> +            core1->rproc->state != RPROC_OFFLINE) {
>>               dev_err(dev, "%s: can not stop core 0 before core 1\n",
>>                   __func__);
>>               ret = -EPERM;

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