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iomap: make the default iomap functions fail softer

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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: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Linus Torvalds 2007-05-04 20:44:23 -07:00
parent 4d4700707c
commit 6cbf0c704d
1 changed files with 20 additions and 7 deletions
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27
lib/iomap.c
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@ -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);