Messages in this thread | | | Date | Tue, 20 May 2008 02:45:35 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] consolidate all within() implementations |
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On Tue, 20 May 2008 10:08:32 +0200 Peter Oberparleiter <oberparleiter@googlemail.com> wrote:
> Harvey Harrison wrote: > > On Mon, 2008-05-19 at 10:45 +0200, Peter Oberparleiter wrote: > >> From: Peter Oberparleiter <peter.oberparleiter@de.ibm.com> > >> > >> This patch consolidates a number of different implementations of the > >> within() function which checks whether an address is within a specified > >> address range. > > > > Would it be that hard to just make them static inlines taking unsigned > > longs? > > I was hoping to get by without the spray of unsigned long casts that > entails the enforcement of this specific parameter type, seeing that > each implementation had it's own combination of longs and void *. > > On the other hand, an inline function would of course be the cleaner > approach, so if the code owners agree, here goes take #2: > > -- > > From: Peter Oberparleiter <peter.oberparleiter@de.ibm.com> > > This patch consolidates a number of different implementations of the > within() function which checks whether an address is within a specified > address range. Apart from parameter typing, existing implementations can > be classified in two categories which differ in the way the range is > specified: > > 1) by start and end address > 2) by start and size > > Case 1) is covered by addr_within() while 2) is covered by > addr_within_len(). > > Signed-off-by: Peter Oberparleiter <peter.oberparleiter@de.ibm.com> > --- > arch/x86/mm/pageattr.c | 20 ++++++++------------ > include/linux/kernel.h | 24 ++++++++++++++++++++++++ > kernel/lockdep.c | 12 +++++------- > kernel/module.c | 35 ++++++++++++++++++++--------------- > 4 files changed, 57 insertions(+), 34 deletions(-) > > Index: linux-2.6.26-rc3/include/linux/kernel.h > =================================================================== > --- linux-2.6.26-rc3.orig/include/linux/kernel.h > +++ linux-2.6.26-rc3/include/linux/kernel.h > @@ -434,6 +434,30 @@ static inline char *pack_hex_byte(char * > __val > __max ? __max: __val; }) > > /** > + * addr_within - check whether address is in start-and-end address range > + * @addr: address > + * @start: start address (included in range) > + * @end: end address (excluded from range) > + */ > +static inline int addr_within(unsigned long addr, unsigned long start, > + unsigned long end) > +{ > + return (addr >= start) && (addr < end); > +} > + > +/** > + * addr_within_len - check whether address is in start-and-length address range > + * @addr: address > + * @start: start of range > + * @len: number of bytes in range > + */ > +static inline int addr_within_len(unsigned long addr, unsigned long start, > + unsigned long len) > +{ > + return (addr >= start) && (addr < (start + len)); > +}
The kernel's use of unsigned long to represent pointers sometimes makes sense, but often gets us into a mess. It's OK in bootup code which fiddles with memory map layout because there is no reason why such code will ever dereference any of the addresses.
But I don't think we can assume this usage pattern when creating a kernel-wide facility in kernel.h.
So yes, I do think that an address-comparison tool like this should operate on void*'s. (They will need to be const void*'s).
> + if (addr_within_len((unsigned long) class->key, > + (unsigned long) start, size)) > + else if (addr_within_len((unsigned long) class->name, > + (unsigned long) start, size)) > + if (addr_within_len(addr, (unsigned long) mod->module_init, > + if (addr_within_len(addr, (unsigned long) mod->module_init, > + || addr_within_len(addr, (unsigned long) mod->module_core, > + if (addr_within_len(addr, (unsigned long) mod->module_init, > + addr_within_len(addr, (unsigned long) mod->module_core, > + if (addr_within_len(addr, (unsigned long) mod->module_init, > + addr_within_len(addr, (unsigned long) mod->module_core, > + if (addr_within_len(addr, (unsigned long) mod->module_core, > + if (addr_within_len(addr, (unsigned long) mod->module_init, > + || addr_within_len(addr, (unsigned long) mod->module_core,
And you've had to add a great pile of casts anwyay?
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