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

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Message-ID: <2bdd6000-82b4-4f57-a950-e9378c321154@ti.com>
Date: Tue, 20 Aug 2024 15:18:42 +0530
From: Beleswar Prasad Padhi <b-padhi@...com>
To: Jan Kiszka <jan.kiszka@...mens.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 20-08-2024 15:09, Jan Kiszka wrote:
> 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.

Check the comment by Andrew Davis[0], that addresses the above issue.

[0]: 
https://lore.kernel.org/all/0bba5293-a55d-4f13-887c-272a54d6e1ca@ti.com/

>
>>> 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
If you are trying to stop and then start the cores from sysfs, that is 
not yet supported. The hang is thus expected.
> 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;