netdev - Re: [PATCH net] forcedeth: Fix an error handling path in nv

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Date: Tue, 23 May 2023 10:39:21 +0200
From: Simon Horman <simon.horman@...igine.com>
To: Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc: Dan Carpenter <dan.carpenter@...aro.org>,
	Rain River <rain.1986.08.12@...il.com>,
	Zhu Yanjun <zyjzyj2000@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Ayaz Abdulla <aabdulla@...dia.com>, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH net] forcedeth: Fix an error handling path in nv_probe()

On Mon, May 22, 2023 at 07:13:43PM +0200, Christophe JAILLET wrote:
> Le 22/05/2023 à 13:10, Simon Horman a écrit :
> > On Mon, May 22, 2023 at 01:35:38PM +0300, Dan Carpenter wrote:
> > > On Mon, May 22, 2023 at 12:12:48PM +0200, Simon Horman wrote:
> > > > On Sat, May 20, 2023 at 10:30:17AM +0200, Christophe JAILLET wrote:
> > > > > If an error occures after calling nv_mgmt_acquire_sema(), it should be
> > > > > undone with a corresponding nv_mgmt_release_sema() call.
> > > > 
> > > > nit: s/occures/occurs/
> > > > 
> > > > > 
> > > > > Add it in the error handling path of the probe as already done in the
> > > > > remove function.
> > > > 
> > > > I was going to ask what happens if nv_mgmt_acquire_sema() fails.
> > > > Then I realised that it always returns 0.
> > > > 
> > > > Perhaps it would be worth changing it's return type to void at some point.
> > > > 
> > > 
> > > What? No?  It returns true on success and false on failure.
> > > 
> > > drivers/net/ethernet/nvidia/forcedeth.c
> > >    5377  static int nv_mgmt_acquire_sema(struct net_device *dev)
> > >    5378  {
> > >    5379          struct fe_priv *np = netdev_priv(dev);
> > >    5380          u8 __iomem *base = get_hwbase(dev);
> > >    5381          int i;
> > >    5382          u32 tx_ctrl, mgmt_sema;
> > >    5383
> > >    5384          for (i = 0; i < 10; i++) {
> > >    5385                  mgmt_sema = readl(base + NvRegTransmitterControl) & NVREG_XMITCTL_MGMT_SEMA_MASK;
> > >    5386                  if (mgmt_sema == NVREG_XMITCTL_MGMT_SEMA_FREE)
> > >    5387                          break;
> > >    5388                  msleep(500);
> > >    5389          }
> > >    5390
> > >    5391          if (mgmt_sema != NVREG_XMITCTL_MGMT_SEMA_FREE)
> > >    5392                  return 0;
> > >    5393
> > >    5394          for (i = 0; i < 2; i++) {
> > >    5395                  tx_ctrl = readl(base + NvRegTransmitterControl);
> > >    5396                  tx_ctrl |= NVREG_XMITCTL_HOST_SEMA_ACQ;
> > >    5397                  writel(tx_ctrl, base + NvRegTransmitterControl);
> > >    5398
> > >    5399                  /* verify that semaphore was acquired */
> > >    5400                  tx_ctrl = readl(base + NvRegTransmitterControl);
> > >    5401                  if (((tx_ctrl & NVREG_XMITCTL_HOST_SEMA_MASK) == NVREG_XMITCTL_HOST_SEMA_ACQ) &&
> > >    5402                      ((tx_ctrl & NVREG_XMITCTL_MGMT_SEMA_MASK) == NVREG_XMITCTL_MGMT_SEMA_FREE)) {
> > >    5403                          np->mgmt_sema = 1;
> > >    5404                          return 1;
> > >                                  ^^^^^^^^^
> > > Success path.
> > > 
> > >    5405                  } else
> > >    5406                          udelay(50);
> > >    5407          }
> > >    5408
> > >    5409          return 0;
> > >    5410  }
> > 
> > Thanks Dan,
> > 
> > my eyes deceived me.
> > 
> > In that case, my question is: what if nv_mgmt_acquire_sema() fails?
> > But I think the answer is that nv_mgmt_release_sema() will do
> > nothing because mgmt_sema is not set.
> 
> At least, it is my understanding.
> 
> Can you fix the typo s/occures/occurs/ when applying the patch, or do you
> really need a v2 only for that?

It's beyond my powers to fix things in that way.
But I'd say there is no need to respin just for a spelling error.

FWIIW,

Reviewed-by: Simon Horman <simon.horman@...igine.com>