linux-kernel - Re: [PATCH 13/15] net: jme: Convert tasklet API to new bottom half workqueue mechanism

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Message-ID: <ba3b8f5907c071e40be68758f2a11662008713e8.camel@redhat.com>
Date: Tue, 25 Jun 2024 12:38:51 +0200
From: Paolo Abeni <pabeni@...hat.com>
To: Allen Pais <allen.lkml@...il.com>, kuba@...nel.org, Guo-Fu Tseng
	 <cooldavid@...ldavid.org>, "David S. Miller" <davem@...emloft.net>, Eric
	Dumazet <edumazet@...gle.com>
Cc: jes@...ined-monkey.org, kda@...ux-powerpc.org, cai.huoqing@...ux.dev, 
 dougmill@...ux.ibm.com, npiggin@...il.com, christophe.leroy@...roup.eu, 
 aneesh.kumar@...nel.org, naveen.n.rao@...ux.ibm.com, nnac123@...ux.ibm.com,
  tlfalcon@...ux.ibm.com, marcin.s.wojtas@...il.com, mlindner@...vell.com, 
 stephen@...workplumber.org, nbd@....name, sean.wang@...iatek.com, 
 Mark-MC.Lee@...iatek.com, lorenzo@...nel.org, matthias.bgg@...il.com, 
 angelogioacchino.delregno@...labora.com, borisp@...dia.com, 
 bryan.whitehead@...rochip.com, UNGLinuxDriver@...rochip.com, 
 louis.peens@...igine.com, richardcochran@...il.com,
 linux-rdma@...r.kernel.org,  linux-kernel@...r.kernel.org,
 linux-acenic@...site.dk, linux-net-drivers@....com,  netdev@...r.kernel.org
Subject: Re: [PATCH 13/15] net: jme: Convert tasklet API to new bottom half
 workqueue mechanism

On Thu, 2024-06-20 at 22:05 -0700, Allen Pais wrote:
> Migrate tasklet APIs to the new bottom half workqueue mechanism. It
> replaces all occurrences of tasklet usage with the appropriate workqueue
> APIs throughout the jme driver. This transition ensures compatibility
> with the latest design and enhances performance.
> 
> Signed-off-by: Allen Pais <allen.lkml@...il.com>
> ---
>  drivers/net/ethernet/jme.c | 72 +++++++++++++++++++-------------------
>  drivers/net/ethernet/jme.h |  8 ++---
>  2 files changed, 40 insertions(+), 40 deletions(-)
> 
> diff --git a/drivers/net/ethernet/jme.c b/drivers/net/ethernet/jme.c
> index b06e24562973..b1a92b851b3b 100644
> --- a/drivers/net/ethernet/jme.c
> +++ b/drivers/net/ethernet/jme.c
> @@ -1141,7 +1141,7 @@ jme_dynamic_pcc(struct jme_adapter *jme)
>  
>  	if (unlikely(dpi->attempt != dpi->cur && dpi->cnt > 5)) {
>  		if (dpi->attempt < dpi->cur)
> -			tasklet_schedule(&jme->rxclean_task);
> +			queue_work(system_bh_wq, &jme->rxclean_bh_work);
>  		jme_set_rx_pcc(jme, dpi->attempt);
>  		dpi->cur = dpi->attempt;
>  		dpi->cnt = 0;
> @@ -1182,9 +1182,9 @@ jme_shutdown_nic(struct jme_adapter *jme)
>  }
>  
>  static void
> -jme_pcc_tasklet(struct tasklet_struct *t)
> +jme_pcc_bh_work(struct work_struct *work)
>  {
> -	struct jme_adapter *jme = from_tasklet(jme, t, pcc_task);
> +	struct jme_adapter *jme = from_work(jme, work, pcc_bh_work);
>  	struct net_device *netdev = jme->dev;
>  
>  	if (unlikely(test_bit(JME_FLAG_SHUTDOWN, &jme->flags))) {
> @@ -1282,9 +1282,9 @@ static void jme_link_change_work(struct work_struct *work)
>  		jme_stop_shutdown_timer(jme);
>  
>  	jme_stop_pcc_timer(jme);
> -	tasklet_disable(&jme->txclean_task);
> -	tasklet_disable(&jme->rxclean_task);
> -	tasklet_disable(&jme->rxempty_task);
> +	disable_work_sync(&jme->txclean_bh_work);
> +	disable_work_sync(&jme->rxclean_bh_work);
> +	disable_work_sync(&jme->rxempty_bh_work);
>  
>  	if (netif_carrier_ok(netdev)) {
>  		jme_disable_rx_engine(jme);
> @@ -1304,7 +1304,7 @@ static void jme_link_change_work(struct work_struct *work)
>  		rc = jme_setup_rx_resources(jme);
>  		if (rc) {
>  			pr_err("Allocating resources for RX error, Device STOPPED!\n");
> -			goto out_enable_tasklet;
> +			goto out_enable_bh_work;
>  		}
>  
>  		rc = jme_setup_tx_resources(jme);
> @@ -1326,22 +1326,22 @@ static void jme_link_change_work(struct work_struct *work)
>  		jme_start_shutdown_timer(jme);
>  	}
>  
> -	goto out_enable_tasklet;
> +	goto out_enable_bh_work;
>  
>  err_out_free_rx_resources:
>  	jme_free_rx_resources(jme);
> -out_enable_tasklet:
> -	tasklet_enable(&jme->txclean_task);
> -	tasklet_enable(&jme->rxclean_task);
> -	tasklet_enable(&jme->rxempty_task);
> +out_enable_bh_work:
> +	enable_and_queue_work(system_bh_wq, &jme->txclean_bh_work);
> +	enable_and_queue_work(system_bh_wq, &jme->rxclean_bh_work);
> +	enable_and_queue_work(system_bh_wq, &jme->rxempty_bh_work);

This will unconditionally schedule the rxempty_bh_work and is AFAICS a
different behavior WRT prior this patch.

In turn the rxempty_bh_work() will emit (almost unconditionally) the
'RX Queue Full!' message, so the change should be visibile to the user.

I think you should queue the work only if it was queued at cancel time.
You likely need additional status to do that.

Thanks,

Paolo