Messages in this thread | | | Date | Wed, 23 Feb 2005 18:22:04 +0000 | From | Jamie Lokier <> | Subject | Re: [PATCH/RFC] Futex mmap_sem deadlock |
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Olof Johansson wrote: > On Wed, Feb 23, 2005 at 07:54:06AM -0800, Linus Torvalds wrote: > > > > Otherwise, a preempt attempt in get_user would not be seen > > > until some future preempt_enable was executed. > > > > True. I guess we should have a "preempt_check_resched()" there too. That's > > what "kunmap_atomic()" does too (which is what we rely on in the other > > case we do this..) > > Ok, this is getting complex enough to warrant get_user_inatomic(), > which means adding it to every arch's uaccess.h. > > Below patch does so. Unfortunately I don't have a Viro setup with cross > compilers for nearly every arch, so I can't make sure it doesn't break > anything. But since I pasted the same code everywhere it shouldn't.
My turn to say uglee.
Firstly, get_user_inatomic is the wrong name.
"inatomic" in __copy_from_user_inatomic means it's called inside a non-premptable region (in atomic...).
Your macro get_user_inatomic is _not_ called inside a non-preemptable region, so it shouldn't be called "inatomic".
(A better name is get_user_no_paging).
Secondly, does this _one_ use (it's not likely to be used elsewhere) justify copying & pasting the same code into every asm-*/uaccess, especially when the code is not in any way arch-specific?
I suggest putting it into futex.c, and make it an inline function which takes "u32 __user *".
-- Jamie - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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