diff mbox series

[7/9] ethernet: stmicro: Simplify PCI devres usage

Message ID 20240819165148.58201-9-pstanner@redhat.com (mailing list archive)
State New, archived
Headers show
Series PCI: Remove pcim_iounmap_regions() | expand

Commit Message

Philipp Stanner Aug. 19, 2024, 4:51 p.m. UTC 
stmicro uses PCI devres in the wrong way. Resources requested
through pcim_* functions don't need to be cleaned up manually in the
remove() callback or in the error unwind path of a probe() function.

Moreover, there is an unnecessary loop which only requests and ioremaps
BAR 0, but iterates over all BARs nevertheless.

Furthermore, pcim_iomap_regions() and pcim_iomap_table() have been
deprecated by the PCI subsystem in commit e354bb84a4c1 ("PCI: Deprecate
pcim_iomap_table(), pcim_iomap_regions_request_all()").

Replace these functions with pcim_iomap_region().

Remove the unnecessary manual pcim_* cleanup calls.

Remove the unnecessary loop over all BARs.

Signed-off-by: Philipp Stanner <pstanner@redhat.com>
---
 .../ethernet/stmicro/stmmac/dwmac-loongson.c  | 25 +++++--------------
 .../net/ethernet/stmicro/stmmac/stmmac_pci.c  | 18 +++++--------
 2 files changed, 12 insertions(+), 31 deletions(-)

Comments

Andy Shevchenko Aug. 19, 2024, 6:28 p.m. UTC | #1 
On Mon, Aug 19, 2024 at 06:51:47PM +0200, Philipp Stanner wrote:
> stmicro uses PCI devres in the wrong way. Resources requested
> through pcim_* functions don't need to be cleaned up manually in the
> remove() callback or in the error unwind path of a probe() function.
> 
> Moreover, there is an unnecessary loop which only requests and ioremaps
> BAR 0, but iterates over all BARs nevertheless.
> 
> Furthermore, pcim_iomap_regions() and pcim_iomap_table() have been
> deprecated by the PCI subsystem in commit e354bb84a4c1 ("PCI: Deprecate
> pcim_iomap_table(), pcim_iomap_regions_request_all()").
> 
> Replace these functions with pcim_iomap_region().
> 
> Remove the unnecessary manual pcim_* cleanup calls.
> 
> Remove the unnecessary loop over all BARs.

...

loongson_dwmac_probe()

> +	memset(&res, 0, sizeof(res));
> +	res.addr = pcim_iomap_region(pdev, 0, pci_name(pdev));
> +	if (IS_ERR(res.addr)) {
> +		ret = PTR_ERR(res.addr);
> +		goto err_disable_device;

It seems your series reveals issues in the error paths of .probe():s
in many drivers...

If we use pcim variant to enable device, why do we need to explicitly
disable it?

>  	}

...

loongson_dwmac_remove()

>  	pci_disable_msi(pdev);
>  	pci_disable_device(pdev);

Not sure why we need these either...
Philipp Stanner Aug. 20, 2024, 7:52 a.m. UTC | #2 
On Mon, 2024-08-19 at 21:28 +0300, Andy Shevchenko wrote:
> On Mon, Aug 19, 2024 at 06:51:47PM +0200, Philipp Stanner wrote:
> > stmicro uses PCI devres in the wrong way. Resources requested
> > through pcim_* functions don't need to be cleaned up manually in
> > the
> > remove() callback or in the error unwind path of a probe()
> > function.
> > 
> > Moreover, there is an unnecessary loop which only requests and
> > ioremaps
> > BAR 0, but iterates over all BARs nevertheless.
> > 
> > Furthermore, pcim_iomap_regions() and pcim_iomap_table() have been
> > deprecated by the PCI subsystem in commit e354bb84a4c1 ("PCI:
> > Deprecate
> > pcim_iomap_table(), pcim_iomap_regions_request_all()").
> > 
> > Replace these functions with pcim_iomap_region().
> > 
> > Remove the unnecessary manual pcim_* cleanup calls.
> > 
> > Remove the unnecessary loop over all BARs.
> 
> ...
> 
> loongson_dwmac_probe()
> 
> > +	memset(&res, 0, sizeof(res));
> > +	res.addr = pcim_iomap_region(pdev, 0, pci_name(pdev));
> > +	if (IS_ERR(res.addr)) {
> > +		ret = PTR_ERR(res.addr);
> > +		goto err_disable_device;
> 
> It seems your series reveals issues in the error paths of .probe():s
> in many drivers...
> 
> If we use pcim variant to enable device, why do we need to explicitly
> disable it?

No.

> 
> >  	}
> 
> ...
> 
> loongson_dwmac_remove()
> 
> >  	pci_disable_msi(pdev);
> >  	pci_disable_device(pdev);
> 
> Not sure why we need these either...

It's complicated.

The code uses pciM_enable_device(), but here in remove
pci_disable_device().

pcim_enable_device() sets up a disable callback which only calls
pci_disable_device() if pcim_pin_device() has not been called.

This code doesn't seem to call pcim_pin_device(), so I think
pci_disable_device() could be removed.


I definitely would not feel confident touching pci_disable_msi(),
though. The AFAIK biggest problem remaining in PCI devres is that the
MSI code base implicitly calls into devres, see here [1]


P.


[1] https://lore.kernel.org/all/ee44ea7ac760e73edad3f20b30b4d2fff66c1a85.camel@redhat.com/
Andy Shevchenko Aug. 20, 2024, 10:37 a.m. UTC | #3 
On Tue, Aug 20, 2024 at 09:52:40AM +0200, Philipp Stanner wrote:
> On Mon, 2024-08-19 at 21:28 +0300, Andy Shevchenko wrote:
> > On Mon, Aug 19, 2024 at 06:51:47PM +0200, Philipp Stanner wrote:

...

> > loongson_dwmac_probe()
> > 
> > > +	memset(&res, 0, sizeof(res));
> > > +	res.addr = pcim_iomap_region(pdev, 0, pci_name(pdev));
> > > +	if (IS_ERR(res.addr)) {
> > > +		ret = PTR_ERR(res.addr);
> > > +		goto err_disable_device;
> > 
> > It seems your series reveals issues in the error paths of .probe():s
> > in many drivers...
> > 
> > If we use pcim variant to enable device, why do we need to explicitly
> > disable it?
> 
> No.

Can you elaborate? No issues being revealed, or no need to disable it
explicitly, or...?

> > >  	}

...

> > loongson_dwmac_remove()
> > 
> > >  	pci_disable_msi(pdev);
> > >  	pci_disable_device(pdev);
> > 
> > Not sure why we need these either...
> 
> It's complicated.
> 
> The code uses pciM_enable_device(), but here in remove
> pci_disable_device().
> 
> pcim_enable_device() sets up a disable callback which only calls
> pci_disable_device() if pcim_pin_device() has not been called.
> 
> This code doesn't seem to call pcim_pin_device(), so I think
> pci_disable_device() could be removed.
> 
> 
> I definitely would not feel confident touching pci_disable_msi(),
> though. The AFAIK biggest problem remaining in PCI devres is that the
> MSI code base implicitly calls into devres, see here [1]

But isn't it a busyness of PCI core to call pci_disable_msi() at the right
moment? Okay, I admit that there might be devices that require a special
workflow WRT MSI, is this the case here?

> [1] https://lore.kernel.org/all/ee44ea7ac760e73edad3f20b30b4d2fff66c1a85.camel@redhat.com/
Philipp Stanner Aug. 20, 2024, 10:53 a.m. UTC | #4 
On Tue, 2024-08-20 at 13:37 +0300, Andy Shevchenko wrote:
> On Tue, Aug 20, 2024 at 09:52:40AM +0200, Philipp Stanner wrote:
> > On Mon, 2024-08-19 at 21:28 +0300, Andy Shevchenko wrote:
> > > On Mon, Aug 19, 2024 at 06:51:47PM +0200, Philipp Stanner wrote:
> 
> ...
> 
> > > loongson_dwmac_probe()
> > > 
> > > > +	memset(&res, 0, sizeof(res));
> > > > +	res.addr = pcim_iomap_region(pdev, 0, pci_name(pdev));
> > > > +	if (IS_ERR(res.addr)) {
> > > > +		ret = PTR_ERR(res.addr);
> > > > +		goto err_disable_device;
> > > 
> > > It seems your series reveals issues in the error paths of
> > > .probe():s
> > > in many drivers...
> > > 
> > > If we use pcim variant to enable device, why do we need to
> > > explicitly
> > > disable it?
> > 
> > No.
> 
> Can you elaborate? No issues being revealed, or no need to disable it
> explicitly, or...?

Oh, my bad, I overlooked your "why" in that question.

We do not explicitly have to disable it. It's wrong / unnecessary, as
many of the other calls you criticized in this series.

pcim_enable_device() (in pci/devres.c) calls devm_add_action(...,
pcim_disable_device,  ...), which will disable the device on driver
detach.

So the call of pci_disable_device() above is redundant. We could remove
it.

> 
> > > >  	}
> 
> ...
> 
> > > loongson_dwmac_remove()
> > > 
> > > >  	pci_disable_msi(pdev);
> > > >  	pci_disable_device(pdev);
> > > 
> > > Not sure why we need these either...
> > 
> > It's complicated.
> > 
> > The code uses pciM_enable_device(), but here in remove
> > pci_disable_device().
> > 
> > pcim_enable_device() sets up a disable callback which only calls
> > pci_disable_device() if pcim_pin_device() has not been called.
> > 
> > This code doesn't seem to call pcim_pin_device(), so I think
> > pci_disable_device() could be removed.
> > 
> > 
> > I definitely would not feel confident touching pci_disable_msi(),
> > though. The AFAIK biggest problem remaining in PCI devres is that
> > the
> > MSI code base implicitly calls into devres, see here [1]
> 
> But isn't it a busyness of PCI core to call pci_disable_msi() at the
> right
> moment? Okay, I admit that there might be devices that require a
> special
> workflow WRT MSI, is this the case here?

I don't know enough about how MSI is intended to be used.

From what I've seen in the code base, pcim_setup_msi_release() does
register a devres callback that will indeed call pci_disable_msi()
after some intermediate calls.

But in my honest opinion, that code is _very_ broken. I was thinking
about how we might clean it up, but couldn't come up with an idea yet.

Only after the code in pci/msi/ has been cleanly separated from
implicit devres I myself would start touching function calls related to
MSI.

That being said, I suspect that one can remove pci_disable_msi() in the
line above. But the risk-benefit-ratio doesn't pay off for me.

P.


> 
> > [1]
> > https://lore.kernel.org/all/ee44ea7ac760e73edad3f20b30b4d2fff66c1a85.camel@redhat.com/
>
diff mbox series

Patch

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-loongson.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-loongson.c
index 9e40c28d453a..5d42a9fad672 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-loongson.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-loongson.c
@@ -50,7 +50,7 @@  static int loongson_dwmac_probe(struct pci_dev *pdev, const struct pci_device_id
 	struct plat_stmmacenet_data *plat;
 	struct stmmac_resources res;
 	struct device_node *np;
-	int ret, i, phy_mode;
+	int ret, phy_mode;
 
 	np = dev_of_node(&pdev->dev);
 
@@ -88,14 +88,11 @@  static int loongson_dwmac_probe(struct pci_dev *pdev, const struct pci_device_id
 		goto err_put_node;
 	}
 
-	/* Get the base address of device */
-	for (i = 0; i < PCI_STD_NUM_BARS; i++) {
-		if (pci_resource_len(pdev, i) == 0)
-			continue;
-		ret = pcim_iomap_regions(pdev, BIT(0), pci_name(pdev));
-		if (ret)
-			goto err_disable_device;
-		break;
+	memset(&res, 0, sizeof(res));
+	res.addr = pcim_iomap_region(pdev, 0, pci_name(pdev));
+	if (IS_ERR(res.addr)) {
+		ret = PTR_ERR(res.addr);
+		goto err_disable_device;
 	}
 
 	plat->bus_id = of_alias_get_id(np, "ethernet");
@@ -116,8 +113,6 @@  static int loongson_dwmac_probe(struct pci_dev *pdev, const struct pci_device_id
 
 	loongson_default_data(plat);
 	pci_enable_msi(pdev);
-	memset(&res, 0, sizeof(res));
-	res.addr = pcim_iomap_table(pdev)[0];
 
 	res.irq = of_irq_get_byname(np, "macirq");
 	if (res.irq < 0) {
@@ -158,18 +153,10 @@  static void loongson_dwmac_remove(struct pci_dev *pdev)
 {
 	struct net_device *ndev = dev_get_drvdata(&pdev->dev);
 	struct stmmac_priv *priv = netdev_priv(ndev);
-	int i;
 
 	of_node_put(priv->plat->mdio_node);
 	stmmac_dvr_remove(&pdev->dev);
 
-	for (i = 0; i < PCI_STD_NUM_BARS; i++) {
-		if (pci_resource_len(pdev, i) == 0)
-			continue;
-		pcim_iounmap_regions(pdev, BIT(i));
-		break;
-	}
-
 	pci_disable_msi(pdev);
 	pci_disable_device(pdev);
 }
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_pci.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_pci.c
index 352b01678c22..f89a8a54c4e8 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_pci.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_pci.c
@@ -188,11 +188,11 @@  static int stmmac_pci_probe(struct pci_dev *pdev,
 		return ret;
 	}
 
-	/* Get the base address of device */
+	/* Request the base address BAR of device */
 	for (i = 0; i < PCI_STD_NUM_BARS; i++) {
 		if (pci_resource_len(pdev, i) == 0)
 			continue;
-		ret = pcim_iomap_regions(pdev, BIT(i), pci_name(pdev));
+		ret = pcim_request_region(pdev, i, pci_name(pdev));
 		if (ret)
 			return ret;
 		break;
@@ -205,7 +205,10 @@  static int stmmac_pci_probe(struct pci_dev *pdev,
 		return ret;
 
 	memset(&res, 0, sizeof(res));
-	res.addr = pcim_iomap_table(pdev)[i];
+	/* Get the base address of device */
+	res.addr = pcim_iomap(pdev, i, 0);
+	if (!res.addr)
+		return -ENOMEM;
 	res.wol_irq = pdev->irq;
 	res.irq = pdev->irq;
 
@@ -231,16 +234,7 @@  static int stmmac_pci_probe(struct pci_dev *pdev,
  */
 static void stmmac_pci_remove(struct pci_dev *pdev)
 {
-	int i;
-
 	stmmac_dvr_remove(&pdev->dev);
-
-	for (i = 0; i < PCI_STD_NUM_BARS; i++) {
-		if (pci_resource_len(pdev, i) == 0)
-			continue;
-		pcim_iounmap_regions(pdev, BIT(i));
-		break;
-	}
 }
 
 static int __maybe_unused stmmac_pci_suspend(struct device *dev)