Messages in this thread | | | Date | Mon, 29 Jul 2013 07:28:12 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH jiffies] Avoid undefined behavior from signed overflow |
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On Tue, Jul 30, 2013 at 12:01:03AM +1000, Kevin Easton wrote: > Quoting "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>: > > >On Mon, Jul 29, 2013 at 03:30:35PM +1000, caf@guarana.org wrote: > >>Quoting "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>: > >> > ... > >>> > >>>Note that the C standard considers the cast from signed to > >>>unsigned to be implementation-defined, see 6.3.1.3p3. > ... > >> > >>Don't worry, the case from signed to unsigned is actually well-defined - > >>the relevant part is 6.3.1.3p2 (in C99): > >> > >>>Otherwise, if the new type is unsigned, the value is converted by > >>>repeatedly adding or subtracting one more than the maximum value that > >>>can be represented in the new type until the value is in the range of > >>>the new type. > > > >Yep, but we are going in the other direction, from unsigned to signed. > > Ahh, there's an error in the commit message (it says signed to unsigned).
Good catch, fixed!
Thanx, Paul
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