Messages in this thread | | | Date | Wed, 10 Jan 2007 14:43:56 -0800 (PST) | From | Linus Torvalds <> | Subject | Re: [PATCH] mm: pagefault_{disable,enable}() |
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On Wed, 10 Jan 2007, Geert Uytterhoeven wrote: > > > The REAL problem seems to be that the m68k preempt.h (or rather, to be > > exact, asm/thread_info.h) doesn't do things right, and while it exposes > > "inc_preempt_count()", it doesn't expose enough information to actually > > use it. > > > > I think your "current_thread_info()" is broken. > > But struct task_struct is defined in <linux/sched.h>, which cannot be included > in <asm/thread_info.h> due to include recursion hell.
But why do you need "struct task_struct" at all?
The reason this doesn't happen on other platforms is that they don't use "struct task_struct". They use "struct thread_info", which is where the preemption counter is.
The problem on m68k i sthat broken indirection through "current", which is unnecessary. Isn't the thread structure on the stack on m68k too? So you could do what x86 does, and just do
movel %a7,%d0 andl $STACK_MASK,%d0
or something, and thus go directly to the thread-info rather than load it off the task pointer.
Or, if worst comes to worst, you can just hardcode the offset of the thread-info pointer in the "struct task_struct". It's the second word after "state". Ugly, but less so than forcing everybody who does NOT want to have that big <linux/sched.h> dependency to get it.
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