Re: [PATCH net-next v8 3/3] net: stmmac: Add driver support for DWMAC5 common safety IRQ

From: Suraj Jaiswal
Date: Mon Jan 08 2024 - 05:59:11 EST

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Hi Seren,
Please find updated comment.

Thanks
Suraj

On 1/8/2024 1:23 AM, Serge Semin wrote:
> On Wed, Dec 27, 2023 at 04:33:33PM +0530, Suraj Jaiswal wrote:
>> Hi Seren,
>> please find the updated comment .
>>
>> Thanks
>> Suraj
>>
>> On 12/26/2023 4:40 PM, Suraj Jaiswal wrote:
>>> Hi seren
>>> let me check below on test setup once & get back
>>>
>>> Thanks
>>> Suraj
>>>
>>> On 12/22/2023 8:05 PM, Serge Semin wrote:
>>>> On Fri, Dec 22, 2023 at 02:13:49PM +0530, Suraj Jaiswal wrote:
>>>>> HI Serge,
>>>>> please find commnet inline.
>>>>>
>>>>> Thanks
>>>>> Suraj
>>>>>
>>>>> On 12/21/2023 6:19 PM, Serge Semin wrote:
>>>>>> Hi Suraj
>>>>>>
>>>>>> On Thu, Dec 21, 2023 at 01:06:20PM +0530, Suraj Jaiswal wrote:
>>>>>>> Add support to listen HW safety IRQ like ECC(error
>>>>>>> correction code), DPP(data path parity), FSM(finite state
>>>>>>> machine) fault in common IRQ line.
>>>>>>>
>>>>>>> Signed-off-by: Suraj Jaiswal <quic_jsuraj@xxxxxxxxxxx>
>>>>>>
>>>>>> Thanks for taking my notes into account. One more comment is further
>>>>>> below.
>>>>>>
>>>>>>> ---
>>>>>>> drivers/net/ethernet/stmicro/stmmac/common.h | 1 +
>>>>>>> drivers/net/ethernet/stmicro/stmmac/stmmac.h | 3 ++
>>>>>>> .../net/ethernet/stmicro/stmmac/stmmac_main.c | 37 +++++++++++++++++++
>>>>>>> .../ethernet/stmicro/stmmac/stmmac_platform.c | 8 ++++
>>>>>>> 4 files changed, 49 insertions(+)
>>>>>>>
>>>>>>> diff --git a/drivers/net/ethernet/stmicro/stmmac/common.h b/drivers/net/ethernet/stmicro/stmmac/common.h
>>>>>>> index 721c1f8e892f..b9233b09b80f 100644
>>>>>>> --- a/drivers/net/ethernet/stmicro/stmmac/common.h
>>>>>>> +++ b/drivers/net/ethernet/stmicro/stmmac/common.h
>>>>>>> @@ -344,6 +344,7 @@ enum request_irq_err {
>>>>>>> REQ_IRQ_ERR_ALL,
>>>>>>> REQ_IRQ_ERR_TX,
>>>>>>> REQ_IRQ_ERR_RX,
>>>>>>> + REQ_IRQ_ERR_SFTY,
>>>>>>> REQ_IRQ_ERR_SFTY_UE,
>>>>>>> REQ_IRQ_ERR_SFTY_CE,
>>>>>>> REQ_IRQ_ERR_LPI,
>>>>>>> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac.h b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
>>>>>>> index 9f89acf31050..ca3d93851bed 100644
>>>>>>> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac.h
>>>>>>> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
>>>>>>> @@ -31,6 +31,7 @@ struct stmmac_resources {
>>>>>>> int wol_irq;
>>>>>>> int lpi_irq;
>>>>>>> int irq;
>>>>>>> + int sfty_irq;
>>>>>>> int sfty_ce_irq;
>>>>>>> int sfty_ue_irq;
>>>>>>> int rx_irq[MTL_MAX_RX_QUEUES];
>>>>>>> @@ -297,6 +298,7 @@ struct stmmac_priv {
>>>>>>> void __iomem *ptpaddr;
>>>>>>> void __iomem *estaddr;
>>>>>>> unsigned long active_vlans[BITS_TO_LONGS(VLAN_N_VID)];
>>>>>>> + int sfty_irq;
>>>>>>> int sfty_ce_irq;
>>>>>>> int sfty_ue_irq;
>>>>>>> int rx_irq[MTL_MAX_RX_QUEUES];
>>>>>>> @@ -305,6 +307,7 @@ struct stmmac_priv {
>>>>>>> char int_name_mac[IFNAMSIZ + 9];
>>>>>>> char int_name_wol[IFNAMSIZ + 9];
>>>>>>> char int_name_lpi[IFNAMSIZ + 9];
>>>>>>> + char int_name_sfty[IFNAMSIZ + 10];
>>>>>>> char int_name_sfty_ce[IFNAMSIZ + 10];
>>>>>>> char int_name_sfty_ue[IFNAMSIZ + 10];
>>>>>>> char int_name_rx_irq[MTL_MAX_TX_QUEUES][IFNAMSIZ + 14];
>>>>>>> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
>>>>>>> index 47de466e432c..7d4e827dfeab 100644
>>>>>>> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
>>>>>>> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
>>>>>>> @@ -3592,6 +3592,10 @@ static void stmmac_free_irq(struct net_device *dev,
>>>>>>> if (priv->wol_irq > 0 && priv->wol_irq != dev->irq)
>>>>>>> free_irq(priv->wol_irq, dev);
>>>>>>> fallthrough;
>>>>>>> + case REQ_IRQ_ERR_SFTY:
>>>>>>> + if (priv->sfty_irq > 0 && priv->sfty_irq != dev->irq)
>>>>>>> + free_irq(priv->sfty_irq, dev);
>>>>>>> + fallthrough;
>>>>>>> case REQ_IRQ_ERR_WOL:
>>>>>>> free_irq(dev->irq, dev);
>>>>>>> fallthrough;
>>>>>>> @@ -3661,6 +3665,23 @@ static int stmmac_request_irq_multi_msi(struct net_device *dev)
>>>>>>> }
>>>>>>> }
>>>>>>>
>>>>>>> + /* Request the common Safety Feature Correctible/Uncorrectible
>>>>>>> + * Error line in case of another line is used
>>>>>>> + */
>>>>>>> + if (priv->sfty_irq > 0 && priv->sfty_irq != dev->irq) {
>>>>>>> + int_name = priv->int_name_sfty;
>>>>>>> + sprintf(int_name, "%s:%s", dev->name, "safety");
>>>>>>> + ret = request_irq(priv->sfty_irq, stmmac_safety_interrupt,
>>>>>>> + 0, int_name, dev);
>>>>>>> + if (unlikely(ret < 0)) {
>>>>>>> + netdev_err(priv->dev,
>>>>>>> + "%s: alloc sfty MSI %d (error: %d)\n",
>>>>>>> + __func__, priv->sfty_irq, ret);
>>>>>>> + irq_err = REQ_IRQ_ERR_SFTY;
>>>>>>> + goto irq_error;
>>>>>>> + }
>>>>>>> + }
>>>>>>> +
>>>>>>> /* Request the Safety Feature Correctible Error line in
>>>>>>> * case of another line is used
>>>>>>> */
>>>>>>> @@ -3798,6 +3819,21 @@ static int stmmac_request_irq_single(struct net_device *dev)
>>>>>>> }
>>>>>>> }
>>>>>>>
>>>>>>> + /* Request the common Safety Feature Correctible/Uncorrectible
>>>>>>> + * Error line in case of another line is used
>>>>>>> + */
>>>>>>> + if (priv->sfty_irq > 0 && priv->sfty_irq != dev->irq) {
>>>>>>
>>>>>>> + ret = request_irq(priv->sfty_irq, stmmac_safety_interrupt,
>>>>>>> + IRQF_SHARED, dev->name, dev);
>>>>>>
>>>>>> Just noticed yesterday that stmmac_safety_interrupt() is also called
>>>>>> from the stmmac_interrupt() handler which is supposed to be registered
>>>>>> on the generic "mac" IRQ. Won't it cause races around the CSRs
>>>>>> (doubtfully but still worth to note) and the errors handling
>>>>>> (stmmac_global_err()) in case if both IRQs are raised simultaneously?
>>>>>> At the very least it looks suspicious and worth double-checking.
>>>>>>
>>>>>> I also found out that nobody seemed to care that the same handler is
>>>>>> registered on MAC, WoL and LPI IRQ lines. Hmm, no race-related
>>>>>> problems have been reported so far for the platforms with separate
>>>>>> WoL/LPI IRQs. It's either a lucky coincident or the IRQs are always
>>>>>> assigned to the same CPU or the IRQs handle is indeed free of races.
>>>>>> In anyway it looks suspicious too. At the very least AFAICS the DMA
>>>>>> IRQ-handler is indeed racy on the status CSR access. It isn't
>>>>>> cleared-on-read, but write-one-to-clear. So the statistics might be
>>>>>> calculated more than once for the same CSR state. There might be some
>>>>>> other problems I failed to spot on the first glance.
>>>>>>
>>>>>> David, Eric, Jacub, Paolo, your opinion about the note above?
>>>>>>
>>>>>> -Serge(y)
>>>>>>
>>>>
>>>>> <Suraj> We are adding common IRQ similar to already present code for correcteable/uncorrecable https://elixir.bootlin.com/linux/latest/source/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c#L3592.
>>>>
>>>> From that perspective your change in stmmac_request_irq_multi_msi() is
>>>> correct, but stmmac_request_irq_single() is another story. The first
>>>> one method implies assigning the individual IRQ handlers to all
>>>> available lines. The later method assigns the _common_ handler to all
>>>> the lines. The common handler already calls the Safety IRQ handler -
>>>> stmmac_safety_feat_interrupt(). So should the safety IRQ line is
>>>> separately available it's possible to have the Safety IRQ handlers
>>>> executed concurrently - in framework of the common IRQ events handling
>>>> (if safety IRQ is raised during the common IRQ being handled) and
>>>> individual Safety IRQ. It's prune to the race condition I pointed out
>>>> to in my message above. Did you consider that problem?
>>>>
>>>>> Also, we need the sfty IRQ handling as soon as the fault occured & that can only be handled if we have handler attached with sfty IRQ.
>>>>> stmmac_interrupt() will only be triggerd when interrupt triggered for rx/tx packet .
>>>>> while registerting with sfty IRQ will get triggered as soon as emac HW detect the fault.
>>>>
>>>> Please read my comment more carefully. The safety IRQ can be raised
>>>> during the common IRQ handling, thus the
>>>> stmmac_safety_feat_interrupt() method might get to be concurrently
>>>> executed.
>>>>
>>>> -Serge(y)
>>>>
>> <Suraj> Have testing this on device . We have added print in the both the places stmmac_interrupt() as well as sfty interrupt handler.
>> We can see that sfty interrupt handler is getting triggred first & stmmac_safety_feat_interrupt () code added in stmmac_intterupt() is not getting triggred because looks like interrupt status bit register is already getting cleared as part of sfty interrupt handler. So it looks good . Please let us know if any further comment.
>>
>> Please find the log below .
>>
>>
>> / # [ 1505.602173] sj: stmmac_safety_interrupt from sfty IRQ handler
>> [ 1505.607274] qcom-ethqos 23040000.ethernet eth1: Found correctable error in MTL: 'RXCES: MTL RX Memory Error'
>> [ 1505.617395] sj: stmmac_safety_interrupt from sfty IRQ handler
>> [ 1505.622494] qcom-ethqos 23040000.ethernet eth1: Found correctable error in MTL: 'TXCES: MTL TX Memory Error'
>> [ 1505.888913] sj: stmmac_safety_interrupt from sfty IRQ handler
>> [ 1505.894010] qcom-ethqos 23040000.ethernet eth1: Found correctable error in MTL: 'RXCES: MTL RX Memory Error'
>> [ 1506.605821] sj: stmmac_safety_interrupt from sfty IRQ handler
>> [ 1506.610919] qcom-ethqos 23040000.ethernet eth1: Found correctable error in MTL: 'RXCES: MTL RX Memory Error'
>> [ 1506.621034] sj: stmmac_safety_interrupt from sfty IRQ handler
>> [ 1506.626131] qcom-ethqos 23040000.ethernet eth1: Found correctable error in MTL: 'TXCES: MTL TX Memory Error'
>> [ 1507.613036] sj: stmmac_safety_interrupt from sfty IRQ handler
>> [ 1507.618133] qcom-ethqos 23040000.ethernet eth1: Found correctable error in MTL: 'RXCES: MTL RX Memory Error'
>> [ 1507.628249] sj: stmmac_safety_interrupt from sfty IRQ handler
>> [ 1507.633346] qcom-ethqos 23040000.ethernet eth1: Found correctable error in MTL: 'TXCES: MTL TX Memory Error'
>> [ 1508.619034] sj: stmmac_safety_interrupt from sfty IRQ handler
>> [ 1508.624132] qcom-ethqos 23040000.ethernet eth1: Found correctable error in MTL: 'RXCES: MTL RX Memory Error'
>> [ 1508.634245] sj: stmmac_safety_interrupt from sfty IRQ handler
>> [ 1508.639343] qcom-ethqos 23040000.ethernet eth1: Found correctable error in MTL: 'TXCES: MTL TX Memory Error'
>> [ 1509.631151] sj: stmmac_safety_interrupt from sfty IRQ handler
>> [ 1509.636249] qcom-ethqos 23040000.ethernet eth1: Found correctable error in MTL: 'RXCES: MTL RX Memory Error'
>>
>
> The log and the way you were trying to model out the problem don't
> prove that the race condition doesn't exist. They just indicate that
> your test-case doesn't catch the simultaneous MAC and Safety IRQs
> handling.
>
> Moreover AFAICS from the way the stmmac_ops->safety_feat_irq_status()
> callbacks are defined in DW QoS Eth and DW XGMAC modules, the race is
> there. Both
> dwmac5_safety_feat_irq_status()
> and
> dwxgmac3_safety_feat_irq_status()
> get to read the MTL and DMA Safety Interrupts Status register in order
> to check whether the Correctable/Uncorrectable errors have actually
> happened. After that the respective MAC, MTL or DMA error handlers are
> called, which get to clear the IRQs statue by reading and then writing
> the respective MAC DPP FRM, MTL/DMA ECC IRQ status registers. So if
> the stmmac_safety_feat_interrupt() method is concurrently called the
> driver at the very least may end up with printing the errors twice.
>
> -Serge(y)
>
<Suraj> We did not see issue reported 2 time in the verfication.
Also, we can add below change to completetly avoid call of sfty hadling as part of stmmac interrupt if irq is already defined like
below . Let me if below looks good .

static irqreturn_t stmmac_interrupt(int irq, void *dev_id)
{
struct net_device *dev = (struct net_device *)dev_id;
struct stmmac_priv *priv = netdev_priv(dev);

/* Check if adapter is up */
if (test_bit(STMMAC_DOWN, &priv->state))
return IRQ_HANDLED;

+ if (priv->sfty_irq <=0) {
/* Check if a fatal error happened */
if (stmmac_safety_feat_interrupt(priv))
return IRQ_HANDLED;
+ }
/* To handle Common interrupts */
stmmac_common_interrupt(priv);

/* To handle DMA interrupts */
stmmac_dma_interrupt(priv);

return IRQ_HANDLED;
}

>>>>>
>>>>>>> + if (unlikely(ret < 0)) {
>>>>>>> + netdev_err(priv->dev,
>>>>>>> + "%s: ERROR: allocating the sfty IRQ %d (%d)\n",
>>>>>>> + __func__, priv->sfty_irq, ret);
>>>>>>> + irq_err = REQ_IRQ_ERR_SFTY;
>>>>>>> + goto irq_error;
>>>>>>> + }
>>>>>>> + }
>>>>>>> +
>>>>>>> return 0;
>>>>>>>
>>>>>>> irq_error:
>>>>>>> @@ -7462,6 +7498,7 @@ int stmmac_dvr_probe(struct device *device,
>>>>>>> priv->dev->irq = res->irq;
>>>>>>> priv->wol_irq = res->wol_irq;
>>>>>>> priv->lpi_irq = res->lpi_irq;
>>>>>>> + priv->sfty_irq = res->sfty_irq;
>>>>>>> priv->sfty_ce_irq = res->sfty_ce_irq;
>>>>>>> priv->sfty_ue_irq = res->sfty_ue_irq;
>>>>>>> for (i = 0; i < MTL_MAX_RX_QUEUES; i++)
>>>>>>> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
>>>>>>> index 70eadc83ca68..ab250161fd79 100644
>>>>>>> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
>>>>>>> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
>>>>>>> @@ -743,6 +743,14 @@ int stmmac_get_platform_resources(struct platform_device *pdev,
>>>>>>> dev_info(&pdev->dev, "IRQ eth_lpi not found\n");
>>>>>>> }
>>>>>>>
>>>>>>> + stmmac_res->sfty_irq =
>>>>>>> + platform_get_irq_byname_optional(pdev, "sfty");
>>>>>>> + if (stmmac_res->sfty_irq < 0) {
>>>>>>> + if (stmmac_res->sfty_irq == -EPROBE_DEFER)
>>>>>>> + return -EPROBE_DEFER;
>>>>>>> + dev_info(&pdev->dev, "IRQ safety IRQ not found\n");
>>>>>>> + }
>>>>>>> +
>>>>>>> stmmac_res->addr = devm_platform_ioremap_resource(pdev, 0);
>>>>>>>
>>>>>>> return PTR_ERR_OR_ZERO(stmmac_res->addr);
>>>>>>> --
>>>>>>> 2.25.1
>>>>>>>
>>>>>>>
>>>

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