Messages in this thread | | | Date | Sat, 4 Mar 2006 00:43:23 +0100 | From | Adrian Bunk <> | Subject | Re: 2.6.16-rc regression: m68k CONFIG_RMW_INSNS=n compile broken |
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On Fri, Mar 03, 2006 at 03:22:42PM -0800, Linus Torvalds wrote: > > > On Sat, 4 Mar 2006, Adrian Bunk wrote: > > > > It seems the problem is that in the CONFIG_RMW_INSNS=n case, there's no > > cmpxchg #define in include/asm-m68k/system.h required for the > > atomic_add_unless #define in include/asm-m68k/atomic.h. > > Hmm. It seems like it never has been there.. Do you know what brought this > on? Was it Nick's RCU changes from "rcuref_dec_and_test()" to > "atomic_dec_and_test()" and friends?
It was Nick's commit 8426e1f6af0fd7f44d040af7263750c5a52f3cc3 that added atomic_inc_not_zero(), and Nick's patch that changed fs/file_table.c from rcuref_dec_and_test() to atomic_dec_and_test() exposed this problem.
> Judging by your error messages, I _think_ it's the "atomic_inc_not_zero()" > that gets expanded to a cmpxchg() that simply doesn't exist on m68k and > never has.
Exactly, that's what I wanted to say in my report.
> I guess we've never depended on cmpxchg before. Or am I missing something?
It seems this is the case.
And as far as I can see, m68k is the only architecture where cmpxchg isn't always available.
> Linus
cu Adrian
--
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