on 11/10/2012 16:06 Erik Cederstrand said the following: > Hello, > > I'm looking at some Clang Static Analyzer reports in the kernel, and a lot of > them point back to a null pointer dereference in __pcpu_type > (sys/amd64/include/pcpu.h:102) which is defined as: > > 102 /* > 103 * Evaluates to the type of the per-cpu variable name. > 104 */ > 105 #define __pcpu_type(name) > \ > 106 __typeof(((struct pcpu *)0)->name) > > > Which indeed looks like a NULL pointer dereference. Looking at the latest > commit message there, I'm sure the code is correct, but I'm unsure why the > null pointer is OK. I'd appreciate an explanation :-)
Read about __typeof [1]. It's evaluated at compile time, so actual value of an expression does not matter at all. [1] http://gcc.gnu.org/onlinedocs/gcc/Typeof.html -- Andriy Gapon _______________________________________________ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "freebsd-hackers-unsubscr...@freebsd.org"
