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| author | Mikulas Patocka <mpatocka@redhat.com> | 2018-05-30 15:19:22 +0300 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2018-11-20 21:05:09 +0300 |
| commit | 09f916460041ebc16c78e58cd6aca2af0571bb4e (patch) | |
| tree | 9f221b212cef9afdedf8d6367dd1bb903c07b968 | |
| parent | d67598ec188e82e056598f1da37610357981eed6 (diff) | |
| download | linux-09f916460041ebc16c78e58cd6aca2af0571bb4e.tar.xz | |
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>
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>
| -rw-r--r-- | include/linux/compiler.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 36fc145ffbb6..0d45dad6941a 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -105,7 +105,7 @@ 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"))) \ |