linux-kernel - RE: [PATCH v2] driver: crypto: caam: replace this_cpu_ptr with raw_cpu

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Date:   Mon, 15 Nov 2021 02:54:36 +0000
From:   "Li, Meng" <Meng.Li@...driver.com>
To:     "horia.geanta@....com" <horia.geanta@....com>,
        "pankaj.gupta@....com" <pankaj.gupta@....com>,
        "herbert@...dor.apana.org.au" <herbert@...dor.apana.org.au>,
        "davem@...emloft.net" <davem@...emloft.net>
CC:     "linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v2] driver: crypto: caam: replace this_cpu_ptr with
 raw_cpu_ptr

Is there any comments about this patch?

Thanks,
Limeng

> -----Original Message-----
> From: Li, Meng <Meng.Li@...driver.com>
> Sent: Monday, November 1, 2021 11:14 AM
> To: horia.geanta@....com; pankaj.gupta@....com;
> herbert@...dor.apana.org.au; davem@...emloft.net
> Cc: linux-crypto@...r.kernel.org; linux-kernel@...r.kernel.org; Li, Meng
> <Meng.Li@...driver.com>
> Subject: [PATCH v2] driver: crypto: caam: replace this_cpu_ptr with
> raw_cpu_ptr
> 
> When enable the kernel debug config, there is below calltrace detected:
> BUG: using smp_processor_id() in preemptible [00000000] code:
> cryptomgr_test/339 caller is debug_smp_processor_id+0x20/0x30
> CPU: 9 PID: 339 Comm: cryptomgr_test Not tainted 5.10.63-yocto-standard
> #1 Hardware name: NXP Layerscape LX2160ARDB (DT) Call trace:
>  dump_backtrace+0x0/0x1a0
>  show_stack+0x24/0x30
>  dump_stack+0xf0/0x13c
>  check_preemption_disabled+0x100/0x110
>  debug_smp_processor_id+0x20/0x30
>  dpaa2_caam_enqueue+0x10c/0x25c
>  ......
>  cryptomgr_test+0x38/0x60
>  kthread+0x158/0x164
>  ret_from_fork+0x10/0x38
> According to the comment in commit ac5d15b4519f("crypto: caam/qi2
>  - use affine DPIOs "), because preemption is no longer disabled while trying
> to enqueue an FQID, it might be possible to run the enqueue on a different
> CPU(due to migration, when in process context), however this wouldn't be a
> functionality issue. But there will be above calltrace when enable kernel
> debug config. So, replace this_cpu_ptr with raw_cpu_ptr to avoid above call
> trace.
> 
> Fixes: ac5d15b4519f ("crypto: caam/qi2 - use affine DPIOs")
> Cc: stable@...r.kernel.org
> Signed-off-by: Meng Li <Meng.Li@...driver.com>
> ---
> v2:
> 
> Add comment to describe why the raw_cpu_ptr is safe.
>  drivers/crypto/caam/caamalg_qi2.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/crypto/caam/caamalg_qi2.c
> b/drivers/crypto/caam/caamalg_qi2.c
> index 8b8ed77d8715..6753f0e6e55d 100644
> --- a/drivers/crypto/caam/caamalg_qi2.c
> +++ b/drivers/crypto/caam/caamalg_qi2.c
> @@ -5470,7 +5470,7 @@ int dpaa2_caam_enqueue(struct device *dev,
> struct caam_request *req)
>  	dpaa2_fd_set_len(&fd, dpaa2_fl_get_len(&req->fd_flt[1]));
>  	dpaa2_fd_set_flc(&fd, req->flc_dma);
> 
> -	ppriv = this_cpu_ptr(priv->ppriv);
> +	ppriv = raw_cpu_ptr(priv->ppriv);
>  	for (i = 0; i < (priv->dpseci_attr.num_tx_queues << 1); i++) {
>  		err = dpaa2_io_service_enqueue_fq(ppriv->dpio, ppriv-
> >req_fqid,
>  						  &fd);
> --
> 2.17.1