On Wed, 30 May 2018 08:19:22 -0400 (EDT) Mikulas Patocka <[email protected]> wrote:
> The function __builtin_expect returns long type (see the gcc > documentation), and so do macros likely and unlikely. Unfortunatelly, when > CONFIG_PROFILE_ANNOTATED_BRANCHES is selected, the macros likely and > unlikely expand to __branch_check__ and __branch_check__ truncates the Nice catch. > long type to int. This unintended truncation may cause bugs in various > kernel code (we found a bug in dm-writecache because of it), so it's I'm curious to what that bug was. > better to fix __branch_check__ to return long. > > Signed-off-by: Mikulas Patocka <[email protected]> > Cc: [email protected] Anyway, I can pull this in my tree and test it. -- Steve > > --- > include/linux/compiler.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > Index: linux-2.6/include/linux/compiler.h > =================================================================== > --- linux-2.6.orig/include/linux/compiler.h 2018-02-26 20:34:17.000000000 > +0100 > +++ linux-2.6/include/linux/compiler.h 2018-05-30 14:11:53.000000000 > +0200 > @@ -21,7 +21,7 @@ void ftrace_likely_update(struct ftrace_ > #define unlikely_notrace(x) __builtin_expect(!!(x), 0) > > #define __branch_check__(x, expect, is_constant) ({ \ > - int ______r; \ > + long ______r; \ > static struct ftrace_likely_data \ > __attribute__((__aligned__(4))) \ > > __attribute__((section("_ftrace_annotated_branch"))) \ -- dm-devel mailing list [email protected] https://www.redhat.com/mailman/listinfo/dm-devel
