Messages in this thread | | | Date | Mon, 4 Jun 2018 16:54:44 -0400 (EDT) | From | Mikulas Patocka <> | Subject | Re: [PATCH] branch-check: fix long->int truncation when profiling branches |
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On Mon, 4 Jun 2018, Steven Rostedt wrote:
> On Wed, 30 May 2018 08:19:22 -0400 (EDT) > Mikulas Patocka <mpatocka@redhat.com> 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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