PCI: Shrink decoding-disabled window while sizing BARs

__pci_read_base() disables decoding while sizing device BARs.  We can't
print while decoding is disabled, which leads to some rather messy exit
logic.

Coalesce the sizing logic to minimize the time decoding is disabled.  This
lets us print errors where they're detected.

The refactoring also takes advantage of the symmetry of obtaining the BAR's
extent (pci_size) and storing the result as the 'region' for both the
32-bit and 64-bit BARs, consolidating both cases.

No functional change intended.

[bhelgaas: move pci_size() up, per Thomas Petazzoni, Thierry Reding, Kevin Hilman]
Signed-off-by: Myron Stowe <myron.stowe@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Matthew Wilcox <willy@linux.intel.com>

drivers/pci/probe.c

@@ -175,7 +175,6 @@ int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type,
 	u64 l64, sz64, mask64;
 	u16 orig_cmd;
 	struct pci_bus_region region, inverted_region;
-	bool bar_too_big = false, bar_too_high = false, bar_invalid = false;
 
 	mask = type ? PCI_ROM_ADDRESS_MASK : ~0;
 
@@ -201,8 +200,8 @@ int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type,
 	 * memory BAR or a ROM, bit 0 must be clear; if it's an io BAR, bit
 	 * 1 must be clear.
 	 */
-	if (!sz || sz == 0xffffffff)
-		goto fail;
+	if (sz == 0xffffffff)
+		sz = 0;
 
 	/*
 	 * I don't know how l can have all bits set.  Copied from old code.
@@ -215,26 +214,22 @@ int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type,
 		res->flags = decode_bar(dev, l);
 		res->flags |= IORESOURCE_SIZEALIGN;
 		if (res->flags & IORESOURCE_IO) {
-			l &= PCI_BASE_ADDRESS_IO_MASK;
-			sz &= PCI_BASE_ADDRESS_IO_MASK;
-			mask = PCI_BASE_ADDRESS_IO_MASK & (u32) IO_SPACE_LIMIT;
+			l64 = l & PCI_BASE_ADDRESS_IO_MASK;
+			sz64 = sz & PCI_BASE_ADDRESS_IO_MASK;
+			mask64 = PCI_BASE_ADDRESS_IO_MASK & (u32)IO_SPACE_LIMIT;
 		} else {
-			l &= PCI_BASE_ADDRESS_MEM_MASK;
-			sz &= PCI_BASE_ADDRESS_MEM_MASK;
-			mask = (u32)PCI_BASE_ADDRESS_MEM_MASK;
+			l64 = l & PCI_BASE_ADDRESS_MEM_MASK;
+			sz64 = sz & PCI_BASE_ADDRESS_MEM_MASK;
+			mask64 = (u32)PCI_BASE_ADDRESS_MEM_MASK;
 		}
 	} else {
 		res->flags |= (l & IORESOURCE_ROM_ENABLE);
-		l &= PCI_ROM_ADDRESS_MASK;
-		sz &= PCI_ROM_ADDRESS_MASK;
-		mask = (u32)PCI_ROM_ADDRESS_MASK;
+		l64 = l & PCI_ROM_ADDRESS_MASK;
+		sz64 = sz & PCI_ROM_ADDRESS_MASK;
+		mask64 = (u32)PCI_ROM_ADDRESS_MASK;
 	}
 
 	if (res->flags & IORESOURCE_MEM_64) {
-		l64 = l;
-		sz64 = sz;
-		mask64 = mask | (u64)~0 << 32;
-
 		pci_read_config_dword(dev, pos + 4, &l);
 		pci_write_config_dword(dev, pos + 4, ~0);
 		pci_read_config_dword(dev, pos + 4, &sz);
@@ -242,18 +237,27 @@ int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type,
 
 		l64 |= ((u64)l << 32);
 		sz64 |= ((u64)sz << 32);
+		mask64 |= ((u64)~0 << 32);
+	}
 
-		sz64 = pci_size(l64, sz64, mask64);
+	if (!dev->mmio_always_on && (orig_cmd & PCI_COMMAND_DECODE_ENABLE))
+		pci_write_config_word(dev, PCI_COMMAND, orig_cmd);
 
-		if (!sz64)
-			goto fail;
+	if (!sz64)
+		goto fail;
+
+	sz64 = pci_size(l64, sz64, mask64);
+	if (!sz64)
+		goto fail;
 
+	if (res->flags & IORESOURCE_MEM_64) {
 		if ((sizeof(dma_addr_t) < 8 || sizeof(resource_size_t) < 8) &&
 		    sz64 > 0x100000000ULL) {
 			res->flags |= IORESOURCE_UNSET | IORESOURCE_DISABLED;
 			res->start = 0;
 			res->end = 0;
-			bar_too_big = true;
+			dev_err(&dev->dev, "reg 0x%x: can't handle BAR larger than 4GB (size %#010llx)\n",
+				pos, (unsigned long long)sz64);
 			goto out;
 		}
 
@@ -262,22 +266,15 @@ int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type,
 			res->flags |= IORESOURCE_UNSET;
 			res->start = 0;
 			res->end = sz64;
-			bar_too_high = true;
+			dev_info(&dev->dev, "reg 0x%x: can't handle BAR above 4GB (bus address %#010llx)\n",
+				 pos, (unsigned long long)l64);
 			goto out;
-		} else {
-			region.start = l64;
-			region.end = l64 + sz64;
 		}
-	} else {
-		sz = pci_size(l, sz, mask);
-
-		if (!sz)
-			goto fail;
-
-		region.start = l;
-		region.end = l + sz;
 	}
 
+	region.start = l64;
+	region.end = l64 + sz64;
+
 	pcibios_bus_to_resource(dev->bus, res, &region);
 	pcibios_resource_to_bus(dev->bus, &inverted_region, res);
 
@@ -296,7 +293,8 @@ int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type,
 		res->flags |= IORESOURCE_UNSET;
 		res->start = 0;
 		res->end = region.end - region.start;
-		bar_invalid = true;
+		dev_info(&dev->dev, "reg 0x%x: initial BAR value %#010llx invalid\n",
+			 pos, (unsigned long long)region.start);
 	}
 
 	goto out;
@@ -305,19 +303,6 @@ int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type,
 fail:
 	res->flags = 0;
 out:
-	if (!dev->mmio_always_on &&
-	    (orig_cmd & PCI_COMMAND_DECODE_ENABLE))
-		pci_write_config_word(dev, PCI_COMMAND, orig_cmd);
-
-	if (bar_too_big)
-		dev_err(&dev->dev, "reg 0x%x: can't handle BAR larger than 4GB (size %#010llx)\n",
-			pos, (unsigned long long) sz64);
-	if (bar_too_high)
-		dev_info(&dev->dev, "reg 0x%x: can't handle BAR above 4G (bus address %#010llx)\n",
-			 pos, (unsigned long long) l64);
-	if (bar_invalid)
-		dev_info(&dev->dev, "reg 0x%x: initial BAR value %#010llx invalid\n",
-			 pos, (unsigned long long) region.start);
 	if (res->flags)
 		dev_printk(KERN_DEBUG, &dev->dev, "reg 0x%x: %pR\n", pos, res);