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authorMikulas Patocka <mpatocka@redhat.com>2018-05-30 08:19:22 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-07-03 11:23:07 +0200
commit3e4fab744be24bf88dac651c5878c831743c0fbe (patch)
treec03dffc553e5efe21e618e5cbf37ff470756ed70 /include
parent95f871342295f2a616fb28d5e0cf72939fe5db5d (diff)
branch-check: fix long->int truncation when profiling branches
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.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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include')
-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 5ce911db7d88..4f3dfabb680f 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -113,7 +113,7 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);
#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"))) \