From: Nathan Chancellor <natechancellor@gmail.com>
To: Steven Rostedt <rostedt@goodmis.org>, Ingo Molnar <mingo@redhat.com>
Cc: linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com,
David Bolvansky <david.bolvansky@gmail.com>,
Nathan Chancellor <natechancellor@gmail.com>,
Nick Desaulniers <ndesaulniers@google.com>
Subject: [PATCH v2] tracing: Fix clang -Wint-in-bool-context warnings in IF_ASSIGN macro
Date: Thu, 26 Sep 2019 09:22:59 -0700
Message-ID: <20190926162258.466321-1-natechancellor@gmail.com> (raw)
In-Reply-To: <20190925172915.576755-1-natechancellor@gmail.com>
After r372664 in clang, the IF_ASSIGN macro causes a couple hundred
warnings along the lines of:
kernel/trace/trace_output.c:1331:2: warning: converting the enum
constant to a boolean [-Wint-in-bool-context]
kernel/trace/trace.h:409:3: note: expanded from macro
'trace_assign_type'
IF_ASSIGN(var, ent, struct ftrace_graph_ret_entry,
^
kernel/trace/trace.h:371:14: note: expanded from macro 'IF_ASSIGN'
WARN_ON(id && (entry)->type != id); \
^
264 warnings generated.
This warning can catch issues with constructs like:
if (state == A || B)
where the developer really meant:
if (state == A || state == B)
This is currently the only occurrence of the warning in the kernel
tree across defconfig, allyesconfig, allmodconfig for arm32, arm64,
and x86_64. Add the implicit '!= 0' to the WARN_ON statement to fix
the warnings and find potential issues in the future.
Link: https://github.com/llvm/llvm-project/commit/28b38c277a2941e9e891b2db30652cfd962f070b
Link: https://github.com/ClangBuiltLinux/linux/issues/686
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
---
v1 -> v2:
* Update commit message to give context behind the warning and explain
this is currently the only occurrence of this warning in the tree.
* Add Nick's Reviewed-by tag.
kernel/trace/trace.h | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 26b0a08f3c7d..f801d154ff6a 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -365,11 +365,11 @@ static inline struct trace_array *top_trace_array(void)
__builtin_types_compatible_p(typeof(var), type *)
#undef IF_ASSIGN
-#define IF_ASSIGN(var, entry, etype, id) \
- if (FTRACE_CMP_TYPE(var, etype)) { \
- var = (typeof(var))(entry); \
- WARN_ON(id && (entry)->type != id); \
- break; \
+#define IF_ASSIGN(var, entry, etype, id) \
+ if (FTRACE_CMP_TYPE(var, etype)) { \
+ var = (typeof(var))(entry); \
+ WARN_ON(id != 0 && (entry)->type != id); \
+ break; \
}
/* Will cause compile errors if type is not found. */
--
2.23.0
prev parent reply index
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-25 17:29 [PATCH] " Nathan Chancellor
2019-09-25 17:41 ` Nick Desaulniers
2019-09-25 23:41 ` Dávid Bolvanský
[not found] ` <CAOrgDVMqOqKtY-9FNV5iHWmz6GFqsH=ugwYp77Zwfr3Niw0ebg@mail.gmail.com>
2019-09-26 12:15 ` Steven Rostedt
2019-09-26 16:22 ` Nathan Chancellor [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190926162258.466321-1-natechancellor@gmail.com \
--to=natechancellor@gmail.com \
--cc=clang-built-linux@googlegroups.com \
--cc=david.bolvansky@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=ndesaulniers@google.com \
--cc=rostedt@goodmis.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
LKML Archive on lore.kernel.org
Archives are clonable:
git clone --mirror https://lore.kernel.org/lkml/0 lkml/git/0.git
git clone --mirror https://lore.kernel.org/lkml/1 lkml/git/1.git
git clone --mirror https://lore.kernel.org/lkml/2 lkml/git/2.git
git clone --mirror https://lore.kernel.org/lkml/3 lkml/git/3.git
git clone --mirror https://lore.kernel.org/lkml/4 lkml/git/4.git
git clone --mirror https://lore.kernel.org/lkml/5 lkml/git/5.git
git clone --mirror https://lore.kernel.org/lkml/6 lkml/git/6.git
git clone --mirror https://lore.kernel.org/lkml/7 lkml/git/7.git
git clone --mirror https://lore.kernel.org/lkml/8 lkml/git/8.git
git clone --mirror https://lore.kernel.org/lkml/9 lkml/git/9.git
# If you have public-inbox 1.1+ installed, you may
# initialize and index your mirror using the following commands:
public-inbox-init -V2 lkml lkml/ https://lore.kernel.org/lkml \
linux-kernel@vger.kernel.org
public-inbox-index lkml
Example config snippet for mirrors
Newsgroup available over NNTP:
nntp://nntp.lore.kernel.org/org.kernel.vger.linux-kernel
AGPL code for this site: git clone https://public-inbox.org/public-inbox.git