* [PATCH net-next v2] net: wwan: t7xx: fix GFP_KERNEL usage in spin_lock context
@ 2022-05-17 6:48 Ziyang Xuan
2022-05-17 8:35 ` Sergey Ryazanov
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Ziyang Xuan @ 2022-05-17 6:48 UTC (permalink / raw)
To: chandrashekar.devegowda, linuxwwan, chiranjeevi.rapolu,
haijun.liu, m.chetan.kumar, ricardo.martinez, loic.poulain,
ryazanov.s.a, johannes, davem, edumazet, kuba, pabeni, netdev
t7xx_cldma_clear_rxq() call t7xx_cldma_alloc_and_map_skb() in spin_lock
context, But __dev_alloc_skb() in t7xx_cldma_alloc_and_map_skb() uses
GFP_KERNEL, that will introduce scheduling factor in spin_lock context.
Because t7xx_cldma_clear_rxq() is called after stopping CLDMA, so we can
remove the spin_lock from t7xx_cldma_clear_rxq().
Fixes: 39d439047f1d ("net: wwan: t7xx: Add control DMA interface")
Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>
---
drivers/net/wwan/t7xx/t7xx_hif_cldma.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/net/wwan/t7xx/t7xx_hif_cldma.c b/drivers/net/wwan/t7xx/t7xx_hif_cldma.c
index 46066dcd2607..7493285a9606 100644
--- a/drivers/net/wwan/t7xx/t7xx_hif_cldma.c
+++ b/drivers/net/wwan/t7xx/t7xx_hif_cldma.c
@@ -782,10 +782,12 @@ static int t7xx_cldma_clear_rxq(struct cldma_ctrl *md_ctrl, int qnum)
struct cldma_queue *rxq = &md_ctrl->rxq[qnum];
struct cldma_request *req;
struct cldma_gpd *gpd;
- unsigned long flags;
int ret = 0;
- spin_lock_irqsave(&rxq->ring_lock, flags);
+ /* CLDMA has been stopped. There is not any CLDMA IRQ, holding
+ * ring_lock is not needed. Thus we can use functions that may
+ * introduce scheduling.
+ */
t7xx_cldma_q_reset(rxq);
list_for_each_entry(req, &rxq->tr_ring->gpd_ring, entry) {
gpd = req->gpd;
@@ -808,7 +810,6 @@ static int t7xx_cldma_clear_rxq(struct cldma_ctrl *md_ctrl, int qnum)
t7xx_cldma_gpd_set_data_ptr(req->gpd, req->mapped_buff);
}
- spin_unlock_irqrestore(&rxq->ring_lock, flags);
return ret;
}
--
2.25.1
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH net-next v2] net: wwan: t7xx: fix GFP_KERNEL usage in spin_lock context
2022-05-17 6:48 [PATCH net-next v2] net: wwan: t7xx: fix GFP_KERNEL usage in spin_lock context Ziyang Xuan
@ 2022-05-17 8:35 ` Sergey Ryazanov
2022-05-17 8:50 ` Loic Poulain
2022-05-18 18:09 ` Ilpo Järvinen
2 siblings, 0 replies; 6+ messages in thread
From: Sergey Ryazanov @ 2022-05-17 8:35 UTC (permalink / raw)
To: Ziyang Xuan
Cc: Devegowda, Chandrashekar, Intel Corporation, chiranjeevi.rapolu,
Haijun Liu (刘海军),
M Chetan Kumar, Ricardo Martinez, Loic Poulain, Johannes Berg,
David Miller, Eric Dumazet, Jakub Kicinski, Paolo Abeni, netdev
On Tue, May 17, 2022 at 9:30 AM Ziyang Xuan
<william.xuanziyang@huawei.com> wrote:
> t7xx_cldma_clear_rxq() call t7xx_cldma_alloc_and_map_skb() in spin_lock
> context, But __dev_alloc_skb() in t7xx_cldma_alloc_and_map_skb() uses
> GFP_KERNEL, that will introduce scheduling factor in spin_lock context.
>
> Because t7xx_cldma_clear_rxq() is called after stopping CLDMA, so we can
> remove the spin_lock from t7xx_cldma_clear_rxq().
>
> Fixes: 39d439047f1d ("net: wwan: t7xx: Add control DMA interface")
> Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>
Reviewed-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH net-next v2] net: wwan: t7xx: fix GFP_KERNEL usage in spin_lock context
2022-05-17 6:48 [PATCH net-next v2] net: wwan: t7xx: fix GFP_KERNEL usage in spin_lock context Ziyang Xuan
2022-05-17 8:35 ` Sergey Ryazanov
@ 2022-05-17 8:50 ` Loic Poulain
2022-05-18 4:39 ` Ziyang Xuan (William)
2022-05-18 18:09 ` Ilpo Järvinen
2 siblings, 1 reply; 6+ messages in thread
From: Loic Poulain @ 2022-05-17 8:50 UTC (permalink / raw)
To: Ziyang Xuan
Cc: chandrashekar.devegowda, linuxwwan, chiranjeevi.rapolu,
haijun.liu, m.chetan.kumar, ricardo.martinez, ryazanov.s.a,
johannes, davem, edumazet, kuba, pabeni, netdev
Hi Ziyang,
On Tue, 17 May 2022 at 08:30, Ziyang Xuan <william.xuanziyang@huawei.com> wrote:
>
> t7xx_cldma_clear_rxq() call t7xx_cldma_alloc_and_map_skb() in spin_lock
> context, But __dev_alloc_skb() in t7xx_cldma_alloc_and_map_skb() uses
> GFP_KERNEL, that will introduce scheduling factor in spin_lock context.
>
> Because t7xx_cldma_clear_rxq() is called after stopping CLDMA, so we can
> remove the spin_lock from t7xx_cldma_clear_rxq().
>
> Fixes: 39d439047f1d ("net: wwan: t7xx: Add control DMA interface")
> Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>
> ---
You should normally indicate what changed in this v2.
> drivers/net/wwan/t7xx/t7xx_hif_cldma.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/wwan/t7xx/t7xx_hif_cldma.c b/drivers/net/wwan/t7xx/t7xx_hif_cldma.c
> index 46066dcd2607..7493285a9606 100644
> --- a/drivers/net/wwan/t7xx/t7xx_hif_cldma.c
> +++ b/drivers/net/wwan/t7xx/t7xx_hif_cldma.c
> @@ -782,10 +782,12 @@ static int t7xx_cldma_clear_rxq(struct cldma_ctrl *md_ctrl, int qnum)
> struct cldma_queue *rxq = &md_ctrl->rxq[qnum];
> struct cldma_request *req;
> struct cldma_gpd *gpd;
> - unsigned long flags;
> int ret = 0;
>
> - spin_lock_irqsave(&rxq->ring_lock, flags);
> + /* CLDMA has been stopped. There is not any CLDMA IRQ, holding
> + * ring_lock is not needed.
If it makes sense to explain why we don't need locking, the next
sentence is not needed:
> Thus we can use functions that may
> + * introduce scheduling.
> + */
> t7xx_cldma_q_reset(rxq);
> list_for_each_entry(req, &rxq->tr_ring->gpd_ring, entry) {
> gpd = req->gpd;
> @@ -808,7 +810,6 @@ static int t7xx_cldma_clear_rxq(struct cldma_ctrl *md_ctrl, int qnum)
>
> t7xx_cldma_gpd_set_data_ptr(req->gpd, req->mapped_buff);
> }
> - spin_unlock_irqrestore(&rxq->ring_lock, flags);
>
> return ret;
> }
> --
> 2.25.1
>
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH net-next v2] net: wwan: t7xx: fix GFP_KERNEL usage in spin_lock context
2022-05-17 8:50 ` Loic Poulain
@ 2022-05-18 4:39 ` Ziyang Xuan (William)
0 siblings, 0 replies; 6+ messages in thread
From: Ziyang Xuan (William) @ 2022-05-18 4:39 UTC (permalink / raw)
To: Loic Poulain
Cc: chandrashekar.devegowda, linuxwwan, chiranjeevi.rapolu,
haijun.liu, m.chetan.kumar, ricardo.martinez, ryazanov.s.a,
johannes, davem, edumazet, kuba, pabeni, netdev
> Hi Ziyang,
>
> On Tue, 17 May 2022 at 08:30, Ziyang Xuan <william.xuanziyang@huawei.com> wrote:
>>
>> t7xx_cldma_clear_rxq() call t7xx_cldma_alloc_and_map_skb() in spin_lock
>> context, But __dev_alloc_skb() in t7xx_cldma_alloc_and_map_skb() uses
>> GFP_KERNEL, that will introduce scheduling factor in spin_lock context.
>>
>> Because t7xx_cldma_clear_rxq() is called after stopping CLDMA, so we can
>> remove the spin_lock from t7xx_cldma_clear_rxq().
>>
>> Fixes: 39d439047f1d ("net: wwan: t7xx: Add control DMA interface")
>> Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>
>> ---
>
> You should normally indicate what changed in this v2.
>
>> drivers/net/wwan/t7xx/t7xx_hif_cldma.c | 7 ++++---
>> 1 file changed, 4 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/net/wwan/t7xx/t7xx_hif_cldma.c b/drivers/net/wwan/t7xx/t7xx_hif_cldma.c
>> index 46066dcd2607..7493285a9606 100644
>> --- a/drivers/net/wwan/t7xx/t7xx_hif_cldma.c
>> +++ b/drivers/net/wwan/t7xx/t7xx_hif_cldma.c
>> @@ -782,10 +782,12 @@ static int t7xx_cldma_clear_rxq(struct cldma_ctrl *md_ctrl, int qnum)
>> struct cldma_queue *rxq = &md_ctrl->rxq[qnum];
>> struct cldma_request *req;
>> struct cldma_gpd *gpd;
>> - unsigned long flags;
>> int ret = 0;
>>
>> - spin_lock_irqsave(&rxq->ring_lock, flags);
>> + /* CLDMA has been stopped. There is not any CLDMA IRQ, holding
>> + * ring_lock is not needed.
>
> If it makes sense to explain why we don't need locking, the next
> sentence is not needed:
I want to remind the possible developer if he or she want to add spin_lock
here again in future, he or she should check whether there is a scheduling
factor or not here firstly.
>
>
>> Thus we can use functions that may
>> + * introduce scheduling.
>> + */
>> t7xx_cldma_q_reset(rxq);
>> list_for_each_entry(req, &rxq->tr_ring->gpd_ring, entry) {
>> gpd = req->gpd;
>> @@ -808,7 +810,6 @@ static int t7xx_cldma_clear_rxq(struct cldma_ctrl *md_ctrl, int qnum)
>>
>> t7xx_cldma_gpd_set_data_ptr(req->gpd, req->mapped_buff);
>> }
>> - spin_unlock_irqrestore(&rxq->ring_lock, flags);
>>
>> return ret;
>> }
>> --
>> 2.25.1
>>
> .
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH net-next v2] net: wwan: t7xx: fix GFP_KERNEL usage in spin_lock context
2022-05-17 6:48 [PATCH net-next v2] net: wwan: t7xx: fix GFP_KERNEL usage in spin_lock context Ziyang Xuan
2022-05-17 8:35 ` Sergey Ryazanov
2022-05-17 8:50 ` Loic Poulain
@ 2022-05-18 18:09 ` Ilpo Järvinen
2022-05-19 4:20 ` Ziyang Xuan (William)
2 siblings, 1 reply; 6+ messages in thread
From: Ilpo Järvinen @ 2022-05-18 18:09 UTC (permalink / raw)
To: Ziyang Xuan
Cc: chandrashekar.devegowda, linuxwwan, chiranjeevi.rapolu,
haijun.liu, m.chetan.kumar, ricardo.martinez, loic.poulain,
ryazanov.s.a, johannes, davem, edumazet, kuba, pabeni, Netdev
On Tue, 17 May 2022, Ziyang Xuan wrote:
> t7xx_cldma_clear_rxq() call t7xx_cldma_alloc_and_map_skb() in spin_lock
> context, But __dev_alloc_skb() in t7xx_cldma_alloc_and_map_skb() uses
> GFP_KERNEL, that will introduce scheduling factor in spin_lock context.
>
> Because t7xx_cldma_clear_rxq() is called after stopping CLDMA, so we can
> remove the spin_lock from t7xx_cldma_clear_rxq().
>
Perhaps Suggested-by: ... would have been appropriate too.
> Fixes: 39d439047f1d ("net: wwan: t7xx: Add control DMA interface")
> Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>
--
i.
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH net-next v2] net: wwan: t7xx: fix GFP_KERNEL usage in spin_lock context
2022-05-18 18:09 ` Ilpo Järvinen
@ 2022-05-19 4:20 ` Ziyang Xuan (William)
0 siblings, 0 replies; 6+ messages in thread
From: Ziyang Xuan (William) @ 2022-05-19 4:20 UTC (permalink / raw)
To: Ilpo Järvinen
Cc: chandrashekar.devegowda, linuxwwan, chiranjeevi.rapolu,
haijun.liu, m.chetan.kumar, ricardo.martinez, loic.poulain,
ryazanov.s.a, johannes, davem, edumazet, kuba, pabeni, Netdev
> On Tue, 17 May 2022, Ziyang Xuan wrote:
>
>> t7xx_cldma_clear_rxq() call t7xx_cldma_alloc_and_map_skb() in spin_lock
>> context, But __dev_alloc_skb() in t7xx_cldma_alloc_and_map_skb() uses
>> GFP_KERNEL, that will introduce scheduling factor in spin_lock context.
>>
>> Because t7xx_cldma_clear_rxq() is called after stopping CLDMA, so we can
>> remove the spin_lock from t7xx_cldma_clear_rxq().
>>
>
> Perhaps Suggested-by: ... would have been appropriate too.
Yes，I will send the v3 patch.
>
>> Fixes: 39d439047f1d ("net: wwan: t7xx: Add control DMA interface")
>> Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>
>
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2022-05-19 4:20 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2022-05-17 6:48 [PATCH net-next v2] net: wwan: t7xx: fix GFP_KERNEL usage in spin_lock context Ziyang Xuan
2022-05-17 8:35 ` Sergey Ryazanov
2022-05-17 8:50 ` Loic Poulain
2022-05-18 4:39 ` Ziyang Xuan (William)
2022-05-18 18:09 ` Ilpo Järvinen
2022-05-19 4:20 ` Ziyang Xuan (William)
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