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Commit 6cbf0c70 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

iomap: make the default iomap functions fail softer 



We used to BUG_ON() for a badly mapped IO port, which is certainly
correct, but actually made it harder to debug the case where the ATA
drivers had incorrectly mapped a nonconnected ATA port.

So make badly mapped ports trigger a WARN_ON(), and throw the IO away
instead (and return all ones for reads).  For things like broken driver
initialization - which is the most likely cause anyway - that should
mean that the machine comes up and is usable (at least that was the case
for the ATA breakage that triggered this patch).

It tends to be a whole lot easier to do a "dmesg" on a working machine
than to try to capture logs off a dead one.

Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4d470070

lib/iomap.c

+20 −7
Original line number Diff line number Diff line
@@ -35,20 +35,28 @@ 
#define PIO_RESERVED	0x40000UL

#endif



static void bad_io_access(unsigned long port, const char *access)

{

	static int count = 10;

	if (count) {

		count--;

		printk(KERN_ERR "Bad IO access at port %lx (%s)\n", port, access);

		WARN_ON(1);

	}

}



/*

 * Ugly macros are a way of life.

 */

#define VERIFY_PIO(port) BUG_ON((port & ~PIO_MASK) != PIO_OFFSET)



#define IO_COND(addr, is_pio, is_mmio) do {			\

	unsigned long port = (unsigned long __force)addr;	\

	if (port < PIO_RESERVED) {				\

		VERIFY_PIO(port);				\

	if (port >= PIO_RESERVED) {				\

		is_mmio;					\

	} else if (port > PIO_OFFSET) {				\

		port &= PIO_MASK;				\

		is_pio;						\

	} else {						\

		is_mmio;					\

	}							\

	} else							\

		bad_io_access(port, #is_pio );			\

} while (0)



#ifndef pio_read16be
@@ -64,22 +72,27 @@ 
unsigned int fastcall ioread8(void __iomem *addr)

{

	IO_COND(addr, return inb(port), return readb(addr));

	return 0xff;

}

unsigned int fastcall ioread16(void __iomem *addr)

{

	IO_COND(addr, return inw(port), return readw(addr));

	return 0xffff;

}

unsigned int fastcall ioread16be(void __iomem *addr)

{

	IO_COND(addr, return pio_read16be(port), return mmio_read16be(addr));

	return 0xffff;

}

unsigned int fastcall ioread32(void __iomem *addr)

{

	IO_COND(addr, return inl(port), return readl(addr));

	return 0xffffffff;

}

unsigned int fastcall ioread32be(void __iomem *addr)

{

	IO_COND(addr, return pio_read32be(port), return mmio_read32be(addr));

	return 0xffffffff;

}

EXPORT_SYMBOL(ioread8);

EXPORT_SYMBOL(ioread16);