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authorMikulas Patocka <mpatocka@redhat.com>2018-05-30 15:19:22 +0300
committerSteven Rostedt (VMware) <rostedt@goodmis.org>2018-06-05 00:28:20 +0300
commit2026d35741f2c3ece73c11eb7e4a15d7c2df9ebe (patch)
treef05eb8233131e271c1844dd17c8053e450d607b7 /include/linux/compiler.h
parenta9235b544a0ae95fbd56443bdbd251358c7df4c5 (diff)
downloadlinux-2026d35741f2c3ece73c11eb7e4a15d7c2df9ebe.tar.xz
branch-check: fix long->int truncation when profiling branches
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.prod.int.rdu2.redhat.com Cc: Ingo Molnar <mingo@redhat.com> Cc: stable@vger.kernel.org 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>
Diffstat (limited to 'include/linux/compiler.h')
-rw-r--r--include/linux/compiler.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index ab4711c63601..42506e4d1f53 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -21,7 +21,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
#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"))) \