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Date: Tue, 23 Apr 2013 11:52:12 -0400 From: Theodore Ts'o <tytso@....edu> To: Linus Torvalds <torvalds@...ux-foundation.org> Cc: David Laight <David.Laight@...lab.com>, Ingo Molnar <mingo@...nel.org>, "H. Peter Anvin" <hpa@...or.com>, Thomas Gleixner <tglx@...utronix.de>, David Miller <davem@...emloft.net>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, the arch/x86 maintainers <x86@...nel.org>, Network Development <netdev@...r.kernel.org>, "linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org> Subject: Re: Unsigned widening casts of binary "not" operations.. On Tue, Apr 23, 2013 at 08:42:49AM -0700, Linus Torvalds wrote: > The best case is for code that does bitmasking ops like this to avoid > any casts (implicit or explicit) by just avoiding mixed types. That > was, to a large degree, my hope for the sparse patch, but it's > nontrivial. Many types are rather "natural" (ie constants have a > natural "int" type, sizeof() is size_t, etc) and in other cases you > want to do the same ops for two different types (with the case that > caused me to start to look at it being the "align to page boundary" > for a virtual address vs a PAE phys_addr_t) so you can't really avoid > mixing things in some circumstances. Maybe it's worth creating a magic helper function, called something like mask_out() that handles the casting automatically, and it makes it clear to a reader what you're trying to do? - Ted -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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