[PATCH v3] PCI: Add pci_iounmap

[George Cherian]

In case if any architecture selects CONFIG_GENERIC_PCI_IOMAP and not
CONFIG_GENERIC_IOMAP, then the pci_iounmap function is reduced to a NULL
function. Due to this the managed release variants or even the explicit
pci_iounmap calls doesn't really remove the mappings.

This issue is seen on an arm64 based system. arm64 by default selects
only CONFIG_GENERIC_PCI_IOMAP and not CONFIG_GENERIC_IOMAP from this
'commit cb61f6769b88 ("ARM64: use GENERIC_PCI_IOMAP")'

Also '66eab4df288a ("lib: add GENERIC_PCI_IOMAP")' moved only  the iomap
functions to lib/pci_iomap.c. The pci_iounmap() was left in lib/iomap.c
as different achitectures has its own pci_iounmap implementation.
For architectures, which doesn't have pci_iounmap implemented, this
would lead to a potential leak. So provide a generic iounmap function in
lib/pci_iomap.c.

Simple bind/unbind test of any pci driver using pcim_iomap/pci_iomap,
would lead to the following error message after long hour tests

"allocation failed: out of vmalloc space - use vmalloc=<size> to
increase size."

Signed-off-by: George Cherian <george.cherian@xxxxxxxxxxx>
---
* Changes from v2
	- Get rid of the #ifdefs around pci_iounmap()
* Changes from v1
	- Fix the 0-day compilation error.
	- Mark the lib/iomap pci_iounmap call as weak incase
	if any architecture have there own implementation.
 include/asm-generic/io.h        | 4 ++++
 include/asm-generic/iomap.h     | 1 -
 include/asm-generic/pci_iomap.h | 1 +
 lib/pci_iomap.c                 | 6 ++++++
 4 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index dabf8cb7203b..5986b37226b7 100644
--- a/include/asm-generic/io.h
+++ b/include/asm-generic/io.h
@@ -915,12 +915,16 @@ static inline void iowrite64_rep(volatile void __iomem *addr,
 struct pci_dev;
 extern void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long max);
 
+#ifdef CONFIG_GENERIC_PCI_IOMAP
+extern void pci_iounmap(struct pci_dev *dev, void __iomem *p);
+#else
 #ifndef pci_iounmap
 #define pci_iounmap pci_iounmap
 static inline void pci_iounmap(struct pci_dev *dev, void __iomem *p)
 {
 }
 #endif
+#endif /* CONFIG_GENERIC_PCI_IOMAP */
 #endif /* CONFIG_GENERIC_IOMAP */
 
 /*
diff --git a/include/asm-generic/iomap.h b/include/asm-generic/iomap.h
index 649224664969..68c75e26edbd 100644
--- a/include/asm-generic/iomap.h
+++ b/include/asm-generic/iomap.h
@@ -104,7 +104,6 @@ extern void ioport_unmap(void __iomem *);
 #ifdef CONFIG_PCI
 /* Destroy a virtual mapping cookie for a PCI BAR (memory or IO) */
 struct pci_dev;
-extern void pci_iounmap(struct pci_dev *dev, void __iomem *);
 #elif defined(CONFIG_GENERIC_IOMAP)
 struct pci_dev;
 static inline void pci_iounmap(struct pci_dev *dev, void __iomem *addr)
diff --git a/include/asm-generic/pci_iomap.h b/include/asm-generic/pci_iomap.h
index d4f16dcc2ed7..3684307a6b44 100644
--- a/include/asm-generic/pci_iomap.h
+++ b/include/asm-generic/pci_iomap.h
@@ -18,6 +18,7 @@ extern void __iomem *pci_iomap_range(struct pci_dev *dev, int bar,
 extern void __iomem *pci_iomap_wc_range(struct pci_dev *dev, int bar,
 					unsigned long offset,
 					unsigned long maxlen);
+extern void pci_iounmap(struct pci_dev *dev, void __iomem *p);
 /* Create a virtual mapping cookie for a port on a given PCI device.
  * Do not call this directly, it exists to make it easier for architectures
  * to override */
diff --git a/lib/pci_iomap.c b/lib/pci_iomap.c
index 2d3eb1cb73b8..e97b73995af7 100644
--- a/lib/pci_iomap.c
+++ b/lib/pci_iomap.c
@@ -134,4 +134,10 @@ void __iomem *pci_iomap_wc(struct pci_dev *dev, int bar, unsigned long maxlen)
 	return pci_iomap_wc_range(dev, bar, 0, maxlen);
 }
 EXPORT_SYMBOL_GPL(pci_iomap_wc);
+
+void __weak pci_iounmap(struct pci_dev *dev, void __iomem *addr)
+{
+	iounmap(addr);
+}
+EXPORT_SYMBOL(pci_iounmap);
 #endif /* CONFIG_PCI */
-- 
2.25.1