From: Loic Poulain <loic.poulain@linaro.org>
To: Ziyang Xuan <william.xuanziyang@huawei.com>
Cc: chandrashekar.devegowda@intel.com, linuxwwan@intel.com,
chiranjeevi.rapolu@linux.intel.com, haijun.liu@mediatek.com,
m.chetan.kumar@linux.intel.com, ricardo.martinez@linux.intel.com,
ryazanov.s.a@gmail.com, johannes@sipsolutions.net,
davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
pabeni@redhat.com, netdev@vger.kernel.org
Subject: Re: [PATCH net-next v2] net: wwan: t7xx: fix GFP_KERNEL usage in spin_lock context
Date: Tue, 17 May 2022 10:50:51 +0200 [thread overview]
Message-ID: <CAMZdPi-ibG9O9C2m3qVeEAbO6=TLA-8jZzX9Gbm2MQOwT_1vPg@mail.gmail.com> (raw)
In-Reply-To: <20220517064821.3966990-1-william.xuanziyang@huawei.com>
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
>
next prev parent reply other threads:[~2022-05-17 8:51 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
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 [this message]
2022-05-18 4:39 ` Ziyang Xuan (William)
2022-05-18 18:09 ` Ilpo Järvinen
2022-05-19 4:20 ` Ziyang Xuan (William)
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAMZdPi-ibG9O9C2m3qVeEAbO6=TLA-8jZzX9Gbm2MQOwT_1vPg@mail.gmail.com' \
--to=loic.poulain@linaro.org \
--cc=chandrashekar.devegowda@intel.com \
--cc=chiranjeevi.rapolu@linux.intel.com \
--cc=davem@davemloft.net \
--cc=edumazet@google.com \
--cc=haijun.liu@mediatek.com \
--cc=johannes@sipsolutions.net \
--cc=kuba@kernel.org \
--cc=linuxwwan@intel.com \
--cc=m.chetan.kumar@linux.intel.com \
--cc=netdev@vger.kernel.org \
--cc=pabeni@redhat.com \
--cc=ricardo.martinez@linux.intel.com \
--cc=ryazanov.s.a@gmail.com \
--cc=william.xuanziyang@huawei.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).