On Mon, 4 Jun 2018, Steven Rostedt wrote:
> On Wed, 30 May 2018 08:19:22 -0400 (EDT)
> Mikulas Patocka <mpatocka@xxxxxxxxxx> 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.
printk("%ld", writecache_has_error(wc))
... and writecache_has_error was defined as
#define writecache_has_error(wc) (unlikely(READ_ONCE((wc)->error)))
Mikulas
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