Re: [PATCH net] forcedeth: Fix an error handling path in nv_probe()

Simon Horman
2023-05-22T11:18:16Z

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.

So I think we are good.