Date: Wed, 2 Aug 2017 16:54:55 +0300 From: Konstantin Belousov <kostikbel@gmail.com> To: Hans Petter Selasky <hps@selasky.org> Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r321920 - head/sys/sys Message-ID: <20170802135455.GG1700@kib.kiev.ua> In-Reply-To: <37abc595-c80e-a8da-04a8-815f42c634de@selasky.org> References: <201708021014.v72AEHEk061037@repo.freebsd.org> <f7a4a90c-f1d8-b381-27fe-3cf76b574a29@selasky.org> <37abc595-c80e-a8da-04a8-815f42c634de@selasky.org>
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On Wed, Aug 02, 2017 at 02:38:50PM +0200, Hans Petter Selasky wrote: > On 08/02/17 14:36, Hans Petter Selasky wrote: > > On 08/02/17 12:14, Konstantin Belousov wrote: > >> +#define major(x) ((int)((dev_t)(x) >> 32)) /* major number */ > >> +#define minor(x) ((int)((x) & 0xffffffff)) /* minor number */ > >> +#define makedev(x, y) (((dev_t)(x) << 32) | (y)) /* create > >> dev_t */ > > > > One more comment on this issue: > > > > I think makedev(x, y) should be declared like this, to avoid issues when > > "y" is negative: > > > > #define makedev(x, y) (((dev_t)(x) << 32) | (unsigned int)(y)) > > /* create dev_t */ > > > > ??? > > > > --HPS > > > > > > And you'll probably want a final wrapping dev_t cast aswell. 128-bit > numbers are not yet there. > > #define makedev(x, y) ((dev_t)(((dev_t)(x) << 32) | (unsigned > int)(y))) > > /* create dev_t */ I agree with the usefulness of the y cast to unsigned type, but I am not sure what is the use of final dev_t cast. By the usual arithmetic conversion rules, the final type of the '|' is the highest rank type of the operands. Something unusual can only happen if int is wider than dev_t. So I am going to commit the following update. diff --git a/sys/sys/types.h b/sys/sys/types.h index fce57e412ed..30a08724443 100644 --- a/sys/sys/types.h +++ b/sys/sys/types.h @@ -366,7 +366,7 @@ __bitcount64(__uint64_t _x) #define major(x) ((int)((dev_t)(x) >> 32)) /* major number */ #define minor(x) ((int)((x) & 0xffffffff)) /* minor number */ -#define makedev(x, y) (((dev_t)(x) << 32) | (y)) /* create dev_t */ +#define makedev(x, y) (((dev_t)(x) << 32) | (unsigned)(y)) /* create dev_t */ /* * These declarations belong elsewhere, but are repeated here and in
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