linux-kernel - Re: [PATCH] driver: soc: dpio: use the whole functions to protect critical zone

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Date:   Tue, 19 Oct 2021 20:42:27 -0500
From:   Li Yang <leoyang.li@....com>
To:     Meng.Li@...driver.com
Cc:     Youri Querry <youri.querry_1@....com>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        lkml <linux-kernel@...r.kernel.org>,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] driver: soc: dpio: use the whole functions to protect
 critical zone

On Mon, Oct 18, 2021 at 10:07 PM <Meng.Li@...driver.com> wrote:
>
> From: Meng Li <Meng.Li@...driver.com>
>
> In orininal code, use 2 function spin_lock() and local_irq_save() to
> protect the critical zone. But when enable the kernel debug config,
> there are below inconsistent lock state detected.
> ================================
> WARNING: inconsistent lock state
> 5.10.63-yocto-standard #1 Not tainted
> --------------------------------
> inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
> lock_torture_wr/226 [HC0[0]:SC1[5]:HE1:SE0] takes:
> ffff002005b2dd80 (&p->access_spinlock){+.?.}-{3:3}, at: qbman_swp_enqueue_multiple_mem_back+0x44/0x270
> {SOFTIRQ-ON-W} state was registered at:
>   lock_acquire.part.0+0xf8/0x250
>   lock_acquire+0x68/0x84
>   _raw_spin_lock+0x68/0x90
>   qbman_swp_enqueue_multiple_mem_back+0x44/0x270
>   ......
>   cryptomgr_test+0x38/0x60
>   kthread+0x158/0x164
>   ret_from_fork+0x10/0x38
> irq event stamp: 4498
> hardirqs last  enabled at (4498): [<ffff800010fcf980>] _raw_spin_unlock_irqrestore+0x90/0xb0
> hardirqs last disabled at (4497): [<ffff800010fcffc4>] _raw_spin_lock_irqsave+0xd4/0xe0
> softirqs last  enabled at (4458): [<ffff8000100108c4>] __do_softirq+0x674/0x724
> softirqs last disabled at (4465): [<ffff80001005b2a4>] __irq_exit_rcu+0x190/0x19c
>
> other info that might help us debug this:
>  Possible unsafe locking scenario:
>        CPU0
>        ----
>   lock(&p->access_spinlock);
>   <Interrupt>
>     lock(&p->access_spinlock);
>  *** DEADLOCK ***
>
> So, in order to avoid deadlock, use the whole functinos

s/functinos/functions/

> spin_lock_irqsave/spin_unlock_irqrestore() to protect critical zone.
>
> Fixes: 3b2abda7d28c ("soc: fsl: dpio: Replace QMAN array mode with ring mode enqueue")
> Cc: stable@...r.kernel.org
> Signed-off-by: Meng Li <Meng.Li@...driver.com>

Applied for fix.  Thanks.

> ---
>  drivers/soc/fsl/dpio/qbman-portal.c | 9 +++------
>  1 file changed, 3 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/soc/fsl/dpio/qbman-portal.c b/drivers/soc/fsl/dpio/qbman-portal.c
> index 845e91416b58..a56dbe4de34f 100644
> --- a/drivers/soc/fsl/dpio/qbman-portal.c
> +++ b/drivers/soc/fsl/dpio/qbman-portal.c
> @@ -785,8 +785,7 @@ int qbman_swp_enqueue_multiple_mem_back(struct qbman_swp *s,
>         int i, num_enqueued = 0;
>         unsigned long irq_flags;
>
> -       spin_lock(&s->access_spinlock);
> -       local_irq_save(irq_flags);
> +       spin_lock_irqsave(&s->access_spinlock, irq_flags);
>
>         half_mask = (s->eqcr.pi_ci_mask>>1);
>         full_mask = s->eqcr.pi_ci_mask;
> @@ -797,8 +796,7 @@ int qbman_swp_enqueue_multiple_mem_back(struct qbman_swp *s,
>                 s->eqcr.available = qm_cyc_diff(s->eqcr.pi_ring_size,
>                                         eqcr_ci, s->eqcr.ci);
>                 if (!s->eqcr.available) {
> -                       local_irq_restore(irq_flags);
> -                       spin_unlock(&s->access_spinlock);
> +                       spin_unlock_irqrestore(&s->access_spinlock, irq_flags);
>                         return 0;
>                 }
>         }
> @@ -837,8 +835,7 @@ int qbman_swp_enqueue_multiple_mem_back(struct qbman_swp *s,
>         dma_wmb();
>         qbman_write_register(s, QBMAN_CINH_SWP_EQCR_PI,
>                                 (QB_RT_BIT)|(s->eqcr.pi)|s->eqcr.pi_vb);
> -       local_irq_restore(irq_flags);
> -       spin_unlock(&s->access_spinlock);
> +       spin_unlock_irqrestore(&s->access_spinlock, irq_flags);
>
>         return num_enqueued;
>  }
> --
> 2.17.1
>