From: Dean Nelson <dnelson@redhat.com>
Date: Wed, 26 May 2010 13:17:20 -0400
Subject: [pci] cleanup error return for pcix get/set mmrbc calls
Message-id: <20100526131720.5326.33711.send-patch@localhost.localdomain>
Patchwork-id: 25812
O-Subject: [RHEL5.6 PATCH 4/4] PCI: cleanup error return for pcix get and set
	mmrbc functions
Bugzilla: 578492
RH-Acked-by: Prarit Bhargava <prarit@redhat.com>
RH-Acked-by: Don Dutile <ddutile@redhat.com>

Resolves RHBZ 578492.

pcix_get_mmrbc() returns the maximum memory read byte count (mmrbc), if
successful, or an appropriate error value, if not.

Distinguishing errors from correct values and understanding the meaning of an
error can be somewhat confusing in that:

	correct values: 512, 1024, 2048, 4096
	errors: -EINVAL				-22
		PCIBIOS_FUNC_NOT_SUPPORTED	0x81
		PCIBIOS_BAD_VENDOR_ID		0x83
		PCIBIOS_DEVICE_NOT_FOUND	0x86
		PCIBIOS_BAD_REGISTER_NUMBER	0x87
		PCIBIOS_SET_FAILED		0x88
		PCIBIOS_BUFFER_TOO_SMALL	0x89

The PCIBIOS_ errors are returned from the PCI functions generated by the
PCI_OP_READ() and PCI_OP_WRITE() macros.

In a similar manner, pcix_set_mmrbc() also returns the PCIBIOS_ error values
returned from pci_read_config_[word|dword]() and pci_write_config_word().

Following pcix_get_max_mmrbc()'s example, the following patch simply returns
-EINVAL for all PCIBIOS_ errors encountered by pcix_get_mmrbc(), and -EINVAL
or -EIO for those encountered by pcix_set_mmrbc().

This simplification was chosen in light of the fact that none of the current
callers of these functions are interested in the specific type of error
encountered. In the future, should this change, one could simply create a
function that maps each PCIBIOS_ error to a corresponding unique errno value,
which could be called by pcix_get_max_mmrbc(), pcix_get_mmrbc(), and
pcix_set_mmrbc().

Additionally, this patch eliminates some unnecessary variables.

Backport of upstream commit:
http://git.kernel.org/linus/7c9e2b1c4784c6e574f69dbd904b2822f2e04d6e


diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 1722798..470312f 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1620,15 +1620,14 @@ EXPORT_SYMBOL_GPL(pci_reset_function);
 int
 pcix_get_max_mmrbc(struct pci_dev *dev)
 {
-	int err, cap;
+	int cap;
 	u32 stat;
 
 	cap = pci_find_capability(dev, PCI_CAP_ID_PCIX);
 	if (!cap)
 		return -EINVAL;
 
-	err = pci_read_config_dword(dev, cap + PCI_X_STATUS, &stat);
-	if (err)
+	if (pci_read_config_dword(dev, cap + PCI_X_STATUS, &stat))
 		return -EINVAL;
 
 	return 512 << ((stat & PCI_X_STATUS_MAX_READ) >> 21);
@@ -1645,18 +1644,17 @@ EXPORT_SYMBOL(pcix_get_max_mmrbc);
 int
 pcix_get_mmrbc(struct pci_dev *dev)
 {
-	int ret, cap;
+	int cap;
 	u16 cmd;
 
 	cap = pci_find_capability(dev, PCI_CAP_ID_PCIX);
 	if (!cap)
 		return -EINVAL;
 
-	ret = pci_read_config_word(dev, cap + PCI_X_CMD, &cmd);
-	if (!ret)
-		ret = 512 << ((cmd & PCI_X_CMD_MAX_READ) >> 2);
+	if (pci_read_config_word(dev, cap + PCI_X_CMD, &cmd))
+		return -EINVAL;
 
-	return ret;
+	return 512 << ((cmd & PCI_X_CMD_MAX_READ) >> 2);
 }
 EXPORT_SYMBOL(pcix_get_mmrbc);
 
@@ -1672,29 +1670,27 @@ EXPORT_SYMBOL(pcix_get_mmrbc);
 int
 pcix_set_mmrbc(struct pci_dev *dev, int mmrbc)
 {
-	int cap, err = -EINVAL;
+	int cap;
 	u32 stat, v, o;
 	u16 cmd;
 
 	if (mmrbc < 512 || mmrbc > 4096 || (mmrbc & (mmrbc-1)))
-		goto out;
+		return -EINVAL;
 
 	v = ffs(mmrbc) - 10;
 
 	cap = pci_find_capability(dev, PCI_CAP_ID_PCIX);
 	if (!cap)
-		goto out;
+		return -EINVAL;
 
-	err = pci_read_config_dword(dev, cap + PCI_X_STATUS, &stat);
-	if (err)
-		goto out;
+	if (pci_read_config_dword(dev, cap + PCI_X_STATUS, &stat))
+		return -EINVAL;
 
 	if (v > (stat & PCI_X_STATUS_MAX_READ) >> 21)
 		return -E2BIG;
 
-	err = pci_read_config_word(dev, cap + PCI_X_CMD, &cmd);
-	if (err)
-		goto out;
+	if (pci_read_config_word(dev, cap + PCI_X_CMD, &cmd))
+		return -EINVAL;
 
 	o = (cmd & PCI_X_CMD_MAX_READ) >> 2;
 	if (o != v) {
@@ -1704,10 +1700,10 @@ pcix_set_mmrbc(struct pci_dev *dev, int mmrbc)
 
 		cmd &= ~PCI_X_CMD_MAX_READ;
 		cmd |= v << 2;
-		err = pci_write_config_word(dev, cap + PCI_X_CMD, cmd);
+		if (pci_write_config_word(dev, cap + PCI_X_CMD, cmd))
+			return -EIO;
 	}
-out:
-	return err;
+	return 0;
 }
 EXPORT_SYMBOL(pcix_set_mmrbc);