3.16.61-rc1 review patch. If anyone has any objections, please let me know.
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From: Mikulas Patocka mpatocka@redhat.com
commit 2026d35741f2c3ece73c11eb7e4a15d7c2df9ebe upstream.
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 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 better to fix __branch_check__ to return long.
Link: http://lkml.kernel.org/r/alpine.LRH.2.02.1805300818140.24812@file01.intranet...
Cc: Ingo Molnar mingo@redhat.com Fixes: 1f0d69a9fc815 ("tracing: profile likely and unlikely annotations") Signed-off-by: Mikulas Patocka mpatocka@redhat.com Signed-off-by: Steven Rostedt (VMware) rostedt@goodmis.org [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- include/linux/compiler.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -105,7 +105,7 @@ void ftrace_likely_update(struct ftrace_ #define unlikely_notrace(x) __builtin_expect(!!(x), 0)
#define __branch_check__(x, expect) ({ \ - int ______r; \ + long ______r; \ static struct ftrace_branch_data \ __attribute__((__aligned__(4))) \ __attribute__((section("_ftrace_annotated_branch"))) \