linux-kernel - Re: [net-next PATCH v2 4/4] netdev: use napi_schedule bool instead of napi_schedule_prep/__napi

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <CANn89iLtYZJPOQE7OkAbEdmhT8qjzAJ+27poa__3c8Nf0M6u_w@mail.gmail.com>
Date:   Thu, 5 Oct 2023 18:16:26 +0200
From:   Eric Dumazet <edumazet@...gle.com>
To:     Christian Marangi <ansuelsmth@...il.com>
Cc:     Jason Gunthorpe <jgg@...pe.ca>, Leon Romanovsky <leon@...nel.org>,
        Wolfgang Grandegger <wg@...ndegger.com>,
        Marc Kleine-Budde <mkl@...gutronix.de>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Chris Snook <chris.snook@...il.com>,
        Raju Rangoju <rajur@...lsio.com>,
        Jeroen de Borst <jeroendb@...gle.com>,
        Praveen Kaligineedi <pkaligineedi@...gle.com>,
        Shailend Chand <shailend@...gle.com>,
        Douglas Miller <dougmill@...ux.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Nicholas Piggin <npiggin@...il.com>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Nick Child <nnac123@...ux.ibm.com>,
        Haren Myneni <haren@...ux.ibm.com>,
        Rick Lindsley <ricklind@...ux.ibm.com>,
        Dany Madden <danymadden@...ibm.com>,
        Thomas Falcon <tlfalcon@...ux.ibm.com>,
        Tariq Toukan <tariqt@...dia.com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Jose Abreu <joabreu@...opsys.com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Krzysztof Halasa <khalasa@...p.pl>,
        Kalle Valo <kvalo@...nel.org>,
        Jeff Johnson <quic_jjohnson@...cinc.com>,
        Gregory Greenman <gregory.greenman@...el.com>,
        Chandrashekar Devegowda <chandrashekar.devegowda@...el.com>,
        Intel Corporation <linuxwwan@...el.com>,
        Chiranjeevi Rapolu <chiranjeevi.rapolu@...ux.intel.com>,
        Liu Haijun <haijun.liu@...iatek.com>,
        M Chetan Kumar <m.chetan.kumar@...ux.intel.com>,
        Ricardo Martinez <ricardo.martinez@...ux.intel.com>,
        Loic Poulain <loic.poulain@...aro.org>,
        Sergey Ryazanov <ryazanov.s.a@...il.com>,
        Johannes Berg <johannes@...solutions.net>,
        Yuanjun Gong <ruc_gongyuanjun@....com>,
        Simon Horman <horms@...nel.org>, Rob Herring <robh@...nel.org>,
        Ziwei Xiao <ziweixiao@...gle.com>,
        Rushil Gupta <rushilg@...gle.com>,
        Coco Li <lixiaoyan@...gle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Junfeng Guo <junfeng.guo@...el.com>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>, Wei Fang <wei.fang@....com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Yuri Karpov <YKarpov@...ras.ru>,
        Zhengchao Shao <shaozhengchao@...wei.com>,
        Andrew Lunn <andrew@...n.ch>,
        Zheng Zengkai <zhengzengkai@...wei.com>,
        Lee Jones <lee@...nel.org>,
        Maximilian Luz <luzmaximilian@...il.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Dawei Li <set_pte_at@...look.com>,
        Anjaneyulu <pagadala.yesu.anjaneyulu@...el.com>,
        Benjamin Berg <benjamin.berg@...el.com>,
        linux-rdma@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-can@...r.kernel.org, netdev@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org,
        linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org, ath10k@...ts.infradead.org,
        linux-wireless@...r.kernel.org
Subject: Re: [net-next PATCH v2 4/4] netdev: use napi_schedule bool instead of napi_schedule_prep/__napi_schedule

On Tue, Oct 3, 2023 at 8:36 PM Christian Marangi <ansuelsmth@...il.com> wrote:
>
> Replace if condition of napi_schedule_prep/__napi_schedule and use bool
> from napi_schedule directly where possible.
>
> Signed-off-by: Christian Marangi <ansuelsmth@...il.com>
> ---
>  drivers/net/ethernet/atheros/atlx/atl1.c     | 4 +---
>  drivers/net/ethernet/toshiba/tc35815.c       | 4 +---
>  drivers/net/wireless/intel/iwlwifi/pcie/rx.c | 4 +---
>  3 files changed, 3 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/net/ethernet/atheros/atlx/atl1.c b/drivers/net/ethernet/atheros/atlx/atl1.c
> index 02aa6fd8ebc2..a9014d7932db 100644
> --- a/drivers/net/ethernet/atheros/atlx/atl1.c
> +++ b/drivers/net/ethernet/atheros/atlx/atl1.c
> @@ -2446,7 +2446,7 @@ static int atl1_rings_clean(struct napi_struct *napi, int budget)
>
>  static inline int atl1_sched_rings_clean(struct atl1_adapter* adapter)
>  {
> -       if (!napi_schedule_prep(&adapter->napi))
> +       if (!napi_schedule(&adapter->napi))
>                 /* It is possible in case even the RX/TX ints are disabled via IMR
>                  * register the ISR bits are set anyway (but do not produce IRQ).
>                  * To handle such situation the napi functions used to check is
> @@ -2454,8 +2454,6 @@ static inline int atl1_sched_rings_clean(struct atl1_adapter* adapter)
>                  */
>                 return 0;
>
> -       __napi_schedule(&adapter->napi);
> -
>         /*
>          * Disable RX/TX ints via IMR register if it is
>          * allowed. NAPI handler must reenable them in same
> diff --git a/drivers/net/ethernet/toshiba/tc35815.c b/drivers/net/ethernet/toshiba/tc35815.c
> index 14cf6ecf6d0d..a8b8a0e13f9a 100644
> --- a/drivers/net/ethernet/toshiba/tc35815.c
> +++ b/drivers/net/ethernet/toshiba/tc35815.c
> @@ -1436,9 +1436,7 @@ static irqreturn_t tc35815_interrupt(int irq, void *dev_id)
>         if (!(dmactl & DMA_IntMask)) {
>                 /* disable interrupts */
>                 tc_writel(dmactl | DMA_IntMask, &tr->DMA_Ctl);
> -               if (napi_schedule_prep(&lp->napi))
> -                       __napi_schedule(&lp->napi);
> -               else {
> +               if (!napi_schedule(&lp->napi)) {
>                         printk(KERN_ERR "%s: interrupt taken in poll\n",
>                                dev->name);
>                         BUG();

Hmmm... could you also remove this BUG() ? I think this code path can be taken
if some applications are using busy polling.

Or simply rewrite this with the traditional

if (napi_schedule_prep(&lp->napi)) {
   /* disable interrupts */
   tc_writel(dmactl | DMA_IntMask, &tr->DMA_Ctl);
    __napi_schedule(&lp->napi);
}



> diff --git a/drivers/net/wireless/intel/iwlwifi/pcie/rx.c b/drivers/net/wireless/intel/iwlwifi/pcie/rx.c
> index 23b5a0adcbd6..146bc7bd14fb 100644
> --- a/drivers/net/wireless/intel/iwlwifi/pcie/rx.c
> +++ b/drivers/net/wireless/intel/iwlwifi/pcie/rx.c
> @@ -1660,9 +1660,7 @@ irqreturn_t iwl_pcie_irq_rx_msix_handler(int irq, void *dev_id)
>         IWL_DEBUG_ISR(trans, "[%d] Got interrupt\n", entry->entry);
>
>         local_bh_disable();
> -       if (napi_schedule_prep(&rxq->napi))
> -               __napi_schedule(&rxq->napi);
> -       else
> +       if (!napi_schedule(&rxq->napi))
>                 iwl_pcie_clear_irq(trans, entry->entry);

Same remark here about twisted logic.

>         local_bh_enable();
>
> --
> 2.40.1
>