[PATCH v3 0/3] Fix find_first_zero_bit() usage

[PATCH v3 0/3] Fix find_first_zero_bit() usage

[Niklas Cassel]

find_first_zero_bit()'s parameter 'size' is defined in bits,
not in bytes.

Calling find_first_zero_bit() with the wrong size unit
will lead to insidious bugs.

Fix all uses of find_first_zero_bit() called with
sizeof() as size argument in drivers/pci.

Also had to fix broken error handling in pci_epc_epf_link()
in order to do proper error handling for find_first_zero_bit().

Niklas Cassel (3):
  PCI: designware-ep: Fix find_first_zero_bit() usage
  PCI: endpoint: Fix error handling in pci_epc_epf_link()
  PCI: endpoint: Fix find_first_zero_bit() usage

 drivers/pci/dwc/pcie-designware-ep.c | 22 ++++++++++++++--------
 drivers/pci/dwc/pcie-designware.h    |  7 +++++--
 drivers/pci/endpoint/pci-ep-cfs.c    | 14 +++++++++-----
 3 files changed, 28 insertions(+), 15 deletions(-)

-- 
2.14.2

[PATCH v3 1/3] PCI: designware-ep: Fix find_first_zero_bit() usage

[Niklas Cassel]

find_first_zero_bit()'s parameter 'size' is defined in bits,
not in bytes.

find_first_zero_bit() was called with size in bytes rather than bits,
which thus defined a too low upper limit, causing
dw_pcie_ep_inbound_atu() to assign iatu index #4 to both bar 4
and bar 5, which made bar 5 overwrite the settings set by bar 4.

Fix this by using bitmaps with a static upper limit (MAX_IATUS).
256 was chosen since according to the databook, that is the
maximum number of iATUs supported by the IP.

Additionally, make sure that ep->num_ob_windows and ep->num_ib_windows,
which are obtained from device tree, are less than the maximum number of
iATUs (MAX_IATUS).

Fixes: f8aed6ec624f ("PCI: dwc: designware: Add EP mode support")
Signed-off-by: Niklas Cassel <niklas.cassel@axis.com>
---
 drivers/pci/dwc/pcie-designware-ep.c | 22 ++++++++++++++--------
 drivers/pci/dwc/pcie-designware.h    |  7 +++++--
 2 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/drivers/pci/dwc/pcie-designware-ep.c b/drivers/pci/dwc/pcie-designware-ep.c
index d53d5f168363..8b14e7db5487 100644
--- a/drivers/pci/dwc/pcie-designware-ep.c
+++ b/drivers/pci/dwc/pcie-designware-ep.c
@@ -70,8 +70,7 @@ static int dw_pcie_ep_inbound_atu(struct dw_pcie_ep *ep, enum pci_barno bar,
 	u32 free_win;
 	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
 
-	free_win = find_first_zero_bit(&ep->ib_window_map,
-				       sizeof(ep->ib_window_map));
+	free_win = find_first_zero_bit(ep->ib_window_map, ep->num_ib_windows);
 	if (free_win >= ep->num_ib_windows) {
 		dev_err(pci->dev, "no free inbound window\n");
 		return -EINVAL;
@@ -85,7 +84,7 @@ static int dw_pcie_ep_inbound_atu(struct dw_pcie_ep *ep, enum pci_barno bar,
 	}
 
 	ep->bar_to_atu[bar] = free_win;
-	set_bit(free_win, &ep->ib_window_map);
+	set_bit(free_win, ep->ib_window_map);
 
 	return 0;
 }
@@ -96,8 +95,7 @@ static int dw_pcie_ep_outbound_atu(struct dw_pcie_ep *ep, phys_addr_t phys_addr,
 	u32 free_win;
 	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
 
-	free_win = find_first_zero_bit(&ep->ob_window_map,
-				       sizeof(ep->ob_window_map));
+	free_win = find_first_zero_bit(ep->ob_window_map, ep->num_ob_windows);
 	if (free_win >= ep->num_ob_windows) {
 		dev_err(pci->dev, "no free outbound window\n");
 		return -EINVAL;
@@ -106,7 +104,7 @@ static int dw_pcie_ep_outbound_atu(struct dw_pcie_ep *ep, phys_addr_t phys_addr,
 	dw_pcie_prog_outbound_atu(pci, free_win, PCIE_ATU_TYPE_MEM,
 				  phys_addr, pci_addr, size);
 
-	set_bit(free_win, &ep->ob_window_map);
+	set_bit(free_win, ep->ob_window_map);
 	ep->outbound_addr[free_win] = phys_addr;
 
 	return 0;
@@ -121,7 +119,7 @@ static void dw_pcie_ep_clear_bar(struct pci_epc *epc, enum pci_barno bar)
 	dw_pcie_ep_reset_bar(pci, bar);
 
 	dw_pcie_disable_atu(pci, atu_index, DW_PCIE_REGION_INBOUND);
-	clear_bit(atu_index, &ep->ib_window_map);
+	clear_bit(atu_index, ep->ib_window_map);
 }
 
 static int dw_pcie_ep_set_bar(struct pci_epc *epc, enum pci_barno bar,
@@ -175,7 +173,7 @@ static void dw_pcie_ep_unmap_addr(struct pci_epc *epc, phys_addr_t addr)
 		return;
 
 	dw_pcie_disable_atu(pci, atu_index, DW_PCIE_REGION_OUTBOUND);
-	clear_bit(atu_index, &ep->ob_window_map);
+	clear_bit(atu_index, ep->ob_window_map);
 }
 
 static int dw_pcie_ep_map_addr(struct pci_epc *epc, phys_addr_t addr,
@@ -298,12 +296,20 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep)
 		dev_err(dev, "unable to read *num-ib-windows* property\n");
 		return ret;
 	}
+	if (ep->num_ib_windows > MAX_IATUS) {
+		dev_err(dev, "invalid *num-ib-windows*\n");
+		return -EINVAL;
+	}
 
 	ret = of_property_read_u32(np, "num-ob-windows", &ep->num_ob_windows);
 	if (ret < 0) {
 		dev_err(dev, "unable to read *num-ob-windows* property\n");
 		return ret;
 	}
+	if (ep->num_ob_windows > MAX_IATUS) {
+		dev_err(dev, "invalid *num-ob-windows*\n");
+		return -EINVAL;
+	}
 
 	addr = devm_kzalloc(dev, sizeof(phys_addr_t) * ep->num_ob_windows,
 			    GFP_KERNEL);
diff --git a/drivers/pci/dwc/pcie-designware.h b/drivers/pci/dwc/pcie-designware.h
index e5d9d77b778e..189f45264c2a 100644
--- a/drivers/pci/dwc/pcie-designware.h
+++ b/drivers/pci/dwc/pcie-designware.h
@@ -113,6 +113,9 @@
 #define MAX_MSI_IRQS			32
 #define MAX_MSI_CTRLS			(MAX_MSI_IRQS / 32)
 
+/* Maximum number of inbound/outbound iATUs */
+#define MAX_IATUS			256
+
 struct pcie_port;
 struct dw_pcie;
 struct dw_pcie_ep;
@@ -192,8 +195,8 @@ struct dw_pcie_ep {
 	size_t			page_size;
 	u8			bar_to_atu[6];
 	phys_addr_t		*outbound_addr;
-	unsigned long		ib_window_map;
-	unsigned long		ob_window_map;
+	DECLARE_BITMAP(ib_window_map, MAX_IATUS);
+	DECLARE_BITMAP(ob_window_map, MAX_IATUS);
 	u32			num_ib_windows;
 	u32			num_ob_windows;
 };
-- 
2.14.2

[PATCH v3 2/3] PCI: endpoint: Fix error handling in pci_epc_epf_link()

[Niklas Cassel]

The error handling in pci_epc_epf_link() was broken,
since the clean up code for pci_epc_add_epf() did clear_bit(),
even though the matching set_bit() is done after pci_epc_add_epf().

Also, clear_bit() should be done before pci_epc_remove_epf(),
since clean up code should normally do things in the reverse order.

Fixes: d74679911610 ("PCI: endpoint: Introduce configfs entry for configuring EP functions")
Signed-off-by: Niklas Cassel <niklas.cassel@axis.com>
---
 drivers/pci/endpoint/pci-ep-cfs.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/endpoint/pci-ep-cfs.c b/drivers/pci/endpoint/pci-ep-cfs.c
index 4f74386c1ced..e1f5adc9e113 100644
--- a/drivers/pci/endpoint/pci-ep-cfs.c
+++ b/drivers/pci/endpoint/pci-ep-cfs.c
@@ -106,7 +106,7 @@ static int pci_epc_epf_link(struct config_item *epc_item,
 	epf = epf_group->epf;
 	ret = pci_epc_add_epf(epc, epf);
 	if (ret)
-		goto err_add_epf;
+		return ret;
 
 	func_no = find_first_zero_bit(&epc_group->function_num_map,
 				      sizeof(epc_group->function_num_map));
@@ -120,10 +120,8 @@ static int pci_epc_epf_link(struct config_item *epc_item,
 	return 0;
 
 err_epf_bind:
-	pci_epc_remove_epf(epc, epf);
-
-err_add_epf:
 	clear_bit(func_no, &epc_group->function_num_map);
+	pci_epc_remove_epf(epc, epf);
 
 	return ret;
 }
-- 
2.14.2

[PATCH v3 3/3] PCI: endpoint: Fix find_first_zero_bit() usage

[Niklas Cassel]

find_first_zero_bit()'s parameter 'size' is defined in bits,
not in bytes.

Calling find_first_zero_bit() with the wrong size unit
will lead to insidious bugs.

Fix this by calling find_first_zero_bit() with size
BITS_PER_LONG, rather than sizeof().

Also add proper error handling for find_first_zero_bit(),
since this was missing.

Fixes: d74679911610 ("PCI: endpoint: Introduce configfs entry for configuring EP functions")
Signed-off-by: Niklas Cassel <niklas.cassel@axis.com>
---
 drivers/pci/endpoint/pci-ep-cfs.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/endpoint/pci-ep-cfs.c b/drivers/pci/endpoint/pci-ep-cfs.c
index e1f5adc9e113..0a22a7976580 100644
--- a/drivers/pci/endpoint/pci-ep-cfs.c
+++ b/drivers/pci/endpoint/pci-ep-cfs.c
@@ -109,7 +109,12 @@ static int pci_epc_epf_link(struct config_item *epc_item,
 		return ret;
 
 	func_no = find_first_zero_bit(&epc_group->function_num_map,
-				      sizeof(epc_group->function_num_map));
+				      BITS_PER_LONG);
+	if (func_no >= BITS_PER_LONG) {
+		ret = -EINVAL;
+		dev_err(&epc->dev, "failed to link endpoint function device\n");
+		goto err_func_no;
+	}
 	set_bit(func_no, &epc_group->function_num_map);
 	epf->func_no = func_no;
 
@@ -121,6 +126,7 @@ static int pci_epc_epf_link(struct config_item *epc_item,
 
 err_epf_bind:
 	clear_bit(func_no, &epc_group->function_num_map);
+err_func_no:
 	pci_epc_remove_epf(epc, epf);
 
 	return ret;
-- 
2.14.2

Re: [PATCH v3 2/3] PCI: endpoint: Fix error handling in pci_epc_epf_link()

[Lorenzo Pieralisi]

On Mon, Nov 27, 2017 at 04:49:54PM +0100, Niklas Cassel wrote:
> The error handling in pci_epc_epf_link() was broken,

s/was/is

(ie commit logs should be written in the present tense)

> since the clean up code for pci_epc_add_epf() did clear_bit(),

s/did/calls (see above)

> even though the matching set_bit() is done after pci_epc_add_epf().
> 
> Also, clear_bit() should be done before pci_epc_remove_epf(),
> since clean up code should normally do things in the reverse order.
> 
> Fixes: d74679911610 ("PCI: endpoint: Introduce configfs entry for configuring EP functions")
> Signed-off-by: Niklas Cassel <niklas.cassel@axis.com>
> ---
>  drivers/pci/endpoint/pci-ep-cfs.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)

Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

> diff --git a/drivers/pci/endpoint/pci-ep-cfs.c b/drivers/pci/endpoint/pci-ep-cfs.c
> index 4f74386c1ced..e1f5adc9e113 100644
> --- a/drivers/pci/endpoint/pci-ep-cfs.c
> +++ b/drivers/pci/endpoint/pci-ep-cfs.c
> @@ -106,7 +106,7 @@ static int pci_epc_epf_link(struct config_item *epc_item,
>  	epf = epf_group->epf;
>  	ret = pci_epc_add_epf(epc, epf);
>  	if (ret)
> -		goto err_add_epf;
> +		return ret;
>  
>  	func_no = find_first_zero_bit(&epc_group->function_num_map,
>  				      sizeof(epc_group->function_num_map));
> @@ -120,10 +120,8 @@ static int pci_epc_epf_link(struct config_item *epc_item,
>  	return 0;
>  
>  err_epf_bind:
> -	pci_epc_remove_epf(epc, epf);
> -
> -err_add_epf:
>  	clear_bit(func_no, &epc_group->function_num_map);
> +	pci_epc_remove_epf(epc, epf);
>  
>  	return ret;
>  }
> -- 
> 2.14.2
> 

Re: [PATCH v3 1/3] PCI: designware-ep: Fix find_first_zero_bit() usage

[Lorenzo Pieralisi]

On Mon, Nov 27, 2017 at 04:49:53PM +0100, Niklas Cassel wrote:
> find_first_zero_bit()'s parameter 'size' is defined in bits,
> not in bytes.
> 
> find_first_zero_bit() was called with size in bytes rather than bits,
> which thus defined a too low upper limit, causing
> dw_pcie_ep_inbound_atu() to assign iatu index #4 to both bar 4
> and bar 5, which made bar 5 overwrite the settings set by bar 4.

Same comments about past tense usage.

> Fix this by using bitmaps with a static upper limit (MAX_IATUS).

I think that given that we have the size from FW (num_ib/ob_windows),
you should allocate them dynamically (sorry for asking another respin).

> 256 was chosen since according to the databook, that is the

Nit: I think "datasheet" is more appropriate than "databook" here.

> maximum number of iATUs supported by the IP.
> 
> Additionally, make sure that ep->num_ob_windows and ep->num_ib_windows,
> which are obtained from device tree, are less than the maximum number of

s/less/smaller

> iATUs (MAX_IATUS).
> 
> Fixes: f8aed6ec624f ("PCI: dwc: designware: Add EP mode support")
> Signed-off-by: Niklas Cassel <niklas.cassel@axis.com>
> ---
>  drivers/pci/dwc/pcie-designware-ep.c | 22 ++++++++++++++--------
>  drivers/pci/dwc/pcie-designware.h    |  7 +++++--
>  2 files changed, 19 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/pci/dwc/pcie-designware-ep.c b/drivers/pci/dwc/pcie-designware-ep.c
> index d53d5f168363..8b14e7db5487 100644
> --- a/drivers/pci/dwc/pcie-designware-ep.c
> +++ b/drivers/pci/dwc/pcie-designware-ep.c
> @@ -70,8 +70,7 @@ static int dw_pcie_ep_inbound_atu(struct dw_pcie_ep *ep, enum pci_barno bar,
>  	u32 free_win;
>  	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
>  
> -	free_win = find_first_zero_bit(&ep->ib_window_map,
> -				       sizeof(ep->ib_window_map));
> +	free_win = find_first_zero_bit(ep->ib_window_map, ep->num_ib_windows);
>  	if (free_win >= ep->num_ib_windows) {
>  		dev_err(pci->dev, "no free inbound window\n");
>  		return -EINVAL;
> @@ -85,7 +84,7 @@ static int dw_pcie_ep_inbound_atu(struct dw_pcie_ep *ep, enum pci_barno bar,
>  	}
>  
>  	ep->bar_to_atu[bar] = free_win;
> -	set_bit(free_win, &ep->ib_window_map);
> +	set_bit(free_win, ep->ib_window_map);
>  
>  	return 0;
>  }
> @@ -96,8 +95,7 @@ static int dw_pcie_ep_outbound_atu(struct dw_pcie_ep *ep, phys_addr_t phys_addr,
>  	u32 free_win;
>  	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
>  
> -	free_win = find_first_zero_bit(&ep->ob_window_map,
> -				       sizeof(ep->ob_window_map));
> +	free_win = find_first_zero_bit(ep->ob_window_map, ep->num_ob_windows);
>  	if (free_win >= ep->num_ob_windows) {
>  		dev_err(pci->dev, "no free outbound window\n");
>  		return -EINVAL;
> @@ -106,7 +104,7 @@ static int dw_pcie_ep_outbound_atu(struct dw_pcie_ep *ep, phys_addr_t phys_addr,
>  	dw_pcie_prog_outbound_atu(pci, free_win, PCIE_ATU_TYPE_MEM,
>  				  phys_addr, pci_addr, size);
>  
> -	set_bit(free_win, &ep->ob_window_map);
> +	set_bit(free_win, ep->ob_window_map);
>  	ep->outbound_addr[free_win] = phys_addr;
>  
>  	return 0;
> @@ -121,7 +119,7 @@ static void dw_pcie_ep_clear_bar(struct pci_epc *epc, enum pci_barno bar)
>  	dw_pcie_ep_reset_bar(pci, bar);
>  
>  	dw_pcie_disable_atu(pci, atu_index, DW_PCIE_REGION_INBOUND);
> -	clear_bit(atu_index, &ep->ib_window_map);
> +	clear_bit(atu_index, ep->ib_window_map);
>  }
>  
>  static int dw_pcie_ep_set_bar(struct pci_epc *epc, enum pci_barno bar,
> @@ -175,7 +173,7 @@ static void dw_pcie_ep_unmap_addr(struct pci_epc *epc, phys_addr_t addr)
>  		return;
>  
>  	dw_pcie_disable_atu(pci, atu_index, DW_PCIE_REGION_OUTBOUND);
> -	clear_bit(atu_index, &ep->ob_window_map);
> +	clear_bit(atu_index, ep->ob_window_map);
>  }
>  
>  static int dw_pcie_ep_map_addr(struct pci_epc *epc, phys_addr_t addr,
> @@ -298,12 +296,20 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep)
>  		dev_err(dev, "unable to read *num-ib-windows* property\n");
>  		return ret;
>  	}
> +	if (ep->num_ib_windows > MAX_IATUS) {
> +		dev_err(dev, "invalid *num-ib-windows*\n");
> +		return -EINVAL;
> +	}
>  
>  	ret = of_property_read_u32(np, "num-ob-windows", &ep->num_ob_windows);
>  	if (ret < 0) {
>  		dev_err(dev, "unable to read *num-ob-windows* property\n");
>  		return ret;
>  	}
> +	if (ep->num_ob_windows > MAX_IATUS) {
> +		dev_err(dev, "invalid *num-ob-windows*\n");
> +		return -EINVAL;
> +	}
>  
>  	addr = devm_kzalloc(dev, sizeof(phys_addr_t) * ep->num_ob_windows,
>  			    GFP_KERNEL);
> diff --git a/drivers/pci/dwc/pcie-designware.h b/drivers/pci/dwc/pcie-designware.h
> index e5d9d77b778e..189f45264c2a 100644
> --- a/drivers/pci/dwc/pcie-designware.h
> +++ b/drivers/pci/dwc/pcie-designware.h
> @@ -113,6 +113,9 @@
>  #define MAX_MSI_IRQS			32
>  #define MAX_MSI_CTRLS			(MAX_MSI_IRQS / 32)
>  
> +/* Maximum number of inbound/outbound iATUs */
> +#define MAX_IATUS			256
> +
>  struct pcie_port;
>  struct dw_pcie;
>  struct dw_pcie_ep;
> @@ -192,8 +195,8 @@ struct dw_pcie_ep {
>  	size_t			page_size;
>  	u8			bar_to_atu[6];
>  	phys_addr_t		*outbound_addr;
> -	unsigned long		ib_window_map;
> -	unsigned long		ob_window_map;
> +	DECLARE_BITMAP(ib_window_map, MAX_IATUS);
> +	DECLARE_BITMAP(ob_window_map, MAX_IATUS);

Only comment I have on the patch is, make the bitmap dynamic ie allocate
them using eg:

ib_window_map = kzalloc(BITS_TO_LONG(num_ib_windows) * sizeof(long),
GFP_KERNEL);

it is a common pattern in the kernel. I just do not like preallocating
static arrays if we know the real size.

It is correct to check the number of ib/ob windows parsed from DT
against MAX_IATUS, since that's a HW limitation therefore a FW (DT)
bug if they are exceeded.

find_first_zero_bit() should use num_ib/ob_windows as size parameter
(ie current patch is correct).

Thanks,
Lorenzo

>  	u32			num_ib_windows;
>  	u32			num_ob_windows;
>  };
> -- 
> 2.14.2
> 

Re: [PATCH v3 3/3] PCI: endpoint: Fix find_first_zero_bit() usage

[Lorenzo Pieralisi]

On Mon, Nov 27, 2017 at 04:49:55PM +0100, Niklas Cassel wrote:
> find_first_zero_bit()'s parameter 'size' is defined in bits,
> not in bytes.
> 
> Calling find_first_zero_bit() with the wrong size unit
> will lead to insidious bugs.
> 
> Fix this by calling find_first_zero_bit() with size BITS_PER_LONG,
> rather than sizeof().
> 
> Also add proper error handling for find_first_zero_bit(), since this
> was missing.

"Fix this by calling find_first_zero_bit() with size BITS_PER_LONG,
rather than sizeof() and add missing find_first_zero_bit() return
handling"

> Fixes: d74679911610 ("PCI: endpoint: Introduce configfs entry for configuring EP functions")
> Signed-off-by: Niklas Cassel <niklas.cassel@axis.com>
> ---
>  drivers/pci/endpoint/pci-ep-cfs.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/endpoint/pci-ep-cfs.c b/drivers/pci/endpoint/pci-ep-cfs.c
> index e1f5adc9e113..0a22a7976580 100644
> --- a/drivers/pci/endpoint/pci-ep-cfs.c
> +++ b/drivers/pci/endpoint/pci-ep-cfs.c
> @@ -109,7 +109,12 @@ static int pci_epc_epf_link(struct config_item *epc_item,
>  		return ret;
>  
>  	func_no = find_first_zero_bit(&epc_group->function_num_map,
> -				      sizeof(epc_group->function_num_map));
> +				      BITS_PER_LONG);
> +	if (func_no >= BITS_PER_LONG) {
> +		ret = -EINVAL;
> +		dev_err(&epc->dev, "failed to link endpoint function device\n");

I would not log the error for the time being or make it more explicit:

dev_error(&epc->dev, "unsupported number of functions, failed to link
endpoint function device\n");

Side note: we _do_ know the max number of functions the epc supports
(epc->max_functions) when this code is called so we do know the
bitmap size - we can rework this code path based on that (@kishon,
thoughts ?).

Other than that:

Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

> +		goto err_func_no;
> +	}
>  	set_bit(func_no, &epc_group->function_num_map);
>  	epf->func_no = func_no;
>  
> @@ -121,6 +126,7 @@ static int pci_epc_epf_link(struct config_item *epc_item,
>  
>  err_epf_bind:
>  	clear_bit(func_no, &epc_group->function_num_map);
> +err_func_no:
>  	pci_epc_remove_epf(epc, epf);
>  
>  	return ret;
> -- 
> 2.14.2
> 

RE: [PATCH v3 3/3] PCI: endpoint: Fix find_first_zero_bit() usage

[David Laight]

From: Niklas Cassel
> Sent: 27 November 2017 15:50
> find_first_zero_bit()'s parameter 'size' is defined in bits,
> not in bytes.
> 
> Calling find_first_zero_bit() with the wrong size unit
> will lead to insidious bugs.
> 
> Fix this by calling find_first_zero_bit() with size
> BITS_PER_LONG, rather than sizeof().
> 
> Also add proper error handling for find_first_zero_bit(),
> since this was missing.
> 
> Fixes: d74679911610 ("PCI: endpoint: Introduce configfs entry for configuring EP functions")
> Signed-off-by: Niklas Cassel <niklas.cassel@axis.com>
> ---
>  drivers/pci/endpoint/pci-ep-cfs.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/endpoint/pci-ep-cfs.c b/drivers/pci/endpoint/pci-ep-cfs.c
> index e1f5adc9e113..0a22a7976580 100644
> --- a/drivers/pci/endpoint/pci-ep-cfs.c
> +++ b/drivers/pci/endpoint/pci-ep-cfs.c
> @@ -109,7 +109,12 @@ static int pci_epc_epf_link(struct config_item *epc_item,
>  		return ret;
> 
>  	func_no = find_first_zero_bit(&epc_group->function_num_map,
> -				      sizeof(epc_group->function_num_map));
> +				      BITS_PER_LONG);

Surely this should be either 8 * sizeof() or you should use ffz()
that takes a numeric argument rather than the function designed
for arbitrary size bitmaps.

	David

Re: [PATCH v3 3/3] PCI: endpoint: Fix find_first_zero_bit() usage

[Lorenzo Pieralisi]

On Tue, Nov 28, 2017 at 09:53:12AM +0000, David Laight wrote:
> From: Niklas Cassel
> > Sent: 27 November 2017 15:50
> > find_first_zero_bit()'s parameter 'size' is defined in bits,
> > not in bytes.
> > 
> > Calling find_first_zero_bit() with the wrong size unit
> > will lead to insidious bugs.
> > 
> > Fix this by calling find_first_zero_bit() with size
> > BITS_PER_LONG, rather than sizeof().
> > 
> > Also add proper error handling for find_first_zero_bit(),
> > since this was missing.
> > 
> > Fixes: d74679911610 ("PCI: endpoint: Introduce configfs entry for configuring EP functions")
> > Signed-off-by: Niklas Cassel <niklas.cassel@axis.com>
> > ---
> >  drivers/pci/endpoint/pci-ep-cfs.c | 8 +++++++-
> >  1 file changed, 7 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/pci/endpoint/pci-ep-cfs.c b/drivers/pci/endpoint/pci-ep-cfs.c
> > index e1f5adc9e113..0a22a7976580 100644
> > --- a/drivers/pci/endpoint/pci-ep-cfs.c
> > +++ b/drivers/pci/endpoint/pci-ep-cfs.c
> > @@ -109,7 +109,12 @@ static int pci_epc_epf_link(struct config_item *epc_item,
> >  		return ret;
> > 
> >  	func_no = find_first_zero_bit(&epc_group->function_num_map,
> > -				      sizeof(epc_group->function_num_map));
> > +				      BITS_PER_LONG);
> 
> Surely this should be either 8 * sizeof() or you should use ffz()
> that takes a numeric argument rather than the function designed
> for arbitrary size bitmaps.

Do you see a problem with this code ? It can be made a bitmap by
allocating it using epc->max_functions as bitmap number of bits
and that can be made on top of the code above that would go in
as a fix unless you strongly object to it, as Joe mentioned
both ffz+| and find_first_zero_bit()+set_bit() are ok with me as
long as we choose one and fix the issue.

Thanks,
Lorenzo

Re: [PATCH v3 1/3] PCI: designware-ep: Fix find_first_zero_bit() usage

[Lorenzo Pieralisi]

On Mon, Nov 27, 2017 at 04:55:05PM +0000, Lorenzo Pieralisi wrote:
> On Mon, Nov 27, 2017 at 04:49:53PM +0100, Niklas Cassel wrote:
> > find_first_zero_bit()'s parameter 'size' is defined in bits,
> > not in bytes.
> > 
> > find_first_zero_bit() was called with size in bytes rather than bits,
> > which thus defined a too low upper limit, causing
> > dw_pcie_ep_inbound_atu() to assign iatu index #4 to both bar 4
> > and bar 5, which made bar 5 overwrite the settings set by bar 4.
> 
> Same comments about past tense usage.
> 
> > Fix this by using bitmaps with a static upper limit (MAX_IATUS).
> 
> I think that given that we have the size from FW (num_ib/ob_windows),
> you should allocate them dynamically (sorry for asking another respin).
> 
> > 256 was chosen since according to the databook, that is the
> 
> Nit: I think "datasheet" is more appropriate than "databook" here.
> 
> > maximum number of iATUs supported by the IP.
> > 
> > Additionally, make sure that ep->num_ob_windows and ep->num_ib_windows,
> > which are obtained from device tree, are less than the maximum number of
> 
> s/less/smaller
> 
> > iATUs (MAX_IATUS).
> > 
> > Fixes: f8aed6ec624f ("PCI: dwc: designware: Add EP mode support")
> > Signed-off-by: Niklas Cassel <niklas.cassel@axis.com>
> > ---
> >  drivers/pci/dwc/pcie-designware-ep.c | 22 ++++++++++++++--------
> >  drivers/pci/dwc/pcie-designware.h    |  7 +++++--
> >  2 files changed, 19 insertions(+), 10 deletions(-)
> > 
> > diff --git a/drivers/pci/dwc/pcie-designware-ep.c b/drivers/pci/dwc/pcie-designware-ep.c
> > index d53d5f168363..8b14e7db5487 100644
> > --- a/drivers/pci/dwc/pcie-designware-ep.c
> > +++ b/drivers/pci/dwc/pcie-designware-ep.c
> > @@ -70,8 +70,7 @@ static int dw_pcie_ep_inbound_atu(struct dw_pcie_ep *ep, enum pci_barno bar,
> >  	u32 free_win;
> >  	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
> >  
> > -	free_win = find_first_zero_bit(&ep->ib_window_map,
> > -				       sizeof(ep->ib_window_map));
> > +	free_win = find_first_zero_bit(ep->ib_window_map, ep->num_ib_windows);
> >  	if (free_win >= ep->num_ib_windows) {
> >  		dev_err(pci->dev, "no free inbound window\n");
> >  		return -EINVAL;
> > @@ -85,7 +84,7 @@ static int dw_pcie_ep_inbound_atu(struct dw_pcie_ep *ep, enum pci_barno bar,
> >  	}
> >  
> >  	ep->bar_to_atu[bar] = free_win;
> > -	set_bit(free_win, &ep->ib_window_map);
> > +	set_bit(free_win, ep->ib_window_map);
> >  
> >  	return 0;
> >  }
> > @@ -96,8 +95,7 @@ static int dw_pcie_ep_outbound_atu(struct dw_pcie_ep *ep, phys_addr_t phys_addr,
> >  	u32 free_win;
> >  	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
> >  
> > -	free_win = find_first_zero_bit(&ep->ob_window_map,
> > -				       sizeof(ep->ob_window_map));
> > +	free_win = find_first_zero_bit(ep->ob_window_map, ep->num_ob_windows);
> >  	if (free_win >= ep->num_ob_windows) {
> >  		dev_err(pci->dev, "no free outbound window\n");
> >  		return -EINVAL;
> > @@ -106,7 +104,7 @@ static int dw_pcie_ep_outbound_atu(struct dw_pcie_ep *ep, phys_addr_t phys_addr,
> >  	dw_pcie_prog_outbound_atu(pci, free_win, PCIE_ATU_TYPE_MEM,
> >  				  phys_addr, pci_addr, size);
> >  
> > -	set_bit(free_win, &ep->ob_window_map);
> > +	set_bit(free_win, ep->ob_window_map);
> >  	ep->outbound_addr[free_win] = phys_addr;
> >  
> >  	return 0;
> > @@ -121,7 +119,7 @@ static void dw_pcie_ep_clear_bar(struct pci_epc *epc, enum pci_barno bar)
> >  	dw_pcie_ep_reset_bar(pci, bar);
> >  
> >  	dw_pcie_disable_atu(pci, atu_index, DW_PCIE_REGION_INBOUND);
> > -	clear_bit(atu_index, &ep->ib_window_map);
> > +	clear_bit(atu_index, ep->ib_window_map);
> >  }
> >  
> >  static int dw_pcie_ep_set_bar(struct pci_epc *epc, enum pci_barno bar,
> > @@ -175,7 +173,7 @@ static void dw_pcie_ep_unmap_addr(struct pci_epc *epc, phys_addr_t addr)
> >  		return;
> >  
> >  	dw_pcie_disable_atu(pci, atu_index, DW_PCIE_REGION_OUTBOUND);
> > -	clear_bit(atu_index, &ep->ob_window_map);
> > +	clear_bit(atu_index, ep->ob_window_map);
> >  }
> >  
> >  static int dw_pcie_ep_map_addr(struct pci_epc *epc, phys_addr_t addr,
> > @@ -298,12 +296,20 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep)
> >  		dev_err(dev, "unable to read *num-ib-windows* property\n");
> >  		return ret;
> >  	}
> > +	if (ep->num_ib_windows > MAX_IATUS) {
> > +		dev_err(dev, "invalid *num-ib-windows*\n");
> > +		return -EINVAL;
> > +	}
> >  
> >  	ret = of_property_read_u32(np, "num-ob-windows", &ep->num_ob_windows);
> >  	if (ret < 0) {
> >  		dev_err(dev, "unable to read *num-ob-windows* property\n");
> >  		return ret;
> >  	}
> > +	if (ep->num_ob_windows > MAX_IATUS) {
> > +		dev_err(dev, "invalid *num-ob-windows*\n");
> > +		return -EINVAL;
> > +	}
> >  
> >  	addr = devm_kzalloc(dev, sizeof(phys_addr_t) * ep->num_ob_windows,
> >  			    GFP_KERNEL);
> > diff --git a/drivers/pci/dwc/pcie-designware.h b/drivers/pci/dwc/pcie-designware.h
> > index e5d9d77b778e..189f45264c2a 100644
> > --- a/drivers/pci/dwc/pcie-designware.h
> > +++ b/drivers/pci/dwc/pcie-designware.h
> > @@ -113,6 +113,9 @@
> >  #define MAX_MSI_IRQS			32
> >  #define MAX_MSI_CTRLS			(MAX_MSI_IRQS / 32)
> >  
> > +/* Maximum number of inbound/outbound iATUs */
> > +#define MAX_IATUS			256
> > +
> >  struct pcie_port;
> >  struct dw_pcie;
> >  struct dw_pcie_ep;
> > @@ -192,8 +195,8 @@ struct dw_pcie_ep {
> >  	size_t			page_size;
> >  	u8			bar_to_atu[6];
> >  	phys_addr_t		*outbound_addr;
> > -	unsigned long		ib_window_map;
> > -	unsigned long		ob_window_map;
> > +	DECLARE_BITMAP(ib_window_map, MAX_IATUS);
> > +	DECLARE_BITMAP(ob_window_map, MAX_IATUS);
> 
> Only comment I have on the patch is, make the bitmap dynamic ie allocate
> them using eg:
> 
> ib_window_map = kzalloc(BITS_TO_LONG(num_ib_windows) * sizeof(long),
> GFP_KERNEL);
> 
> it is a common pattern in the kernel. I just do not like preallocating
> static arrays if we know the real size.
> 
> It is correct to check the number of ib/ob windows parsed from DT
> against MAX_IATUS, since that's a HW limitation therefore a FW (DT)
> bug if they are exceeded.
> 
> find_first_zero_bit() should use num_ib/ob_windows as size parameter
> (ie current patch is correct).

Hi Niklas,

May I ask you please to update this series to the latest review comments
and send out a v4 so that Bjorn can pull it please ?

Thanks,
Lorenzo