Messages in this thread Patch in this message | | | Date | Wed, 23 Jun 2004 13:49:01 -0500 | Subject | [RFC] replace assorted ASSERT()s by something officially sanctioned | From | (Dean Nelson) |
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It doesn't appear that an officially 'sanctioned' version of ASSERT() or an ASSERT()-like macro exists.
And by the proliferation of its use in the linux 2.6 kernel (I saw over 3000 references to it), it would seem that BUG_ON() does not satisfy all of the requirements of the community.
One problem with BUG_ON() is that it is always enabled. And even though the compiler does a good job of minimizing the impact of the conditional expression, there are times when the conditional check requires the accessing of a cacheline that would not get accessed had the BUG_ON() not been enabled. And if that cacheline were one that is hotly contended for, one's performance can be adversely affected.
For debugging purposes it would be nice to have a version of BUG_ON() that was only enabled if DEBUG was set. This is what appears to be behind the use of the ASSERT()-like macros.
As an example of what I have in mind, I've included the following quilt patch.
Thanks, Dean
Index: linux/include/asm-i386/bug.h =================================================================== --- linux.orig/include/asm-i386/bug.h +++ linux/include/asm-i386/bug.h @@ -21,6 +21,12 @@ #define BUG_ON(condition) do { if (unlikely((condition)!=0)) BUG(); } while(0) +#ifdef DEBUG +#define DBUG_ON(condition) BUG_ON(condition) +#else +#define DBUG_ON(condition) +#endif + #define PAGE_BUG(page) do { \ BUG(); \ } while (0) - 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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