Return-path: Received: from smtprelay0082.hostedemail.com ([216.40.44.82]:46490 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753834AbdCBRuV (ORCPT ); Thu, 2 Mar 2017 12:50:21 -0500 Message-ID: <1488476770.2179.6.camel@perches.com> (sfid-20170302_185217_512980_40B5B950) Subject: Re: [PATCH 24/26] ocfs2: reduce stack size with KASAN From: Joe Perches To: Arnd Bergmann , kasan-dev@googlegroups.com Cc: Andrey Ryabinin , Alexander Potapenko , Dmitry Vyukov , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, linux-wireless@vger.kernel.org, kernel-build-reports@lists.linaro.org, "David S . Miller" Date: Thu, 02 Mar 2017 09:46:10 -0800 In-Reply-To: <20170302163834.2273519-25-arnd@arndb.de> References: <20170302163834.2273519-1-arnd@arndb.de> <20170302163834.2273519-25-arnd@arndb.de> Content-Type: text/plain; charset="ISO-8859-1" Mime-Version: 1.0 Sender: linux-wireless-owner@vger.kernel.org List-ID: On Thu, 2017-03-02 at 17:38 +0100, Arnd Bergmann wrote: > The internal logging infrastructure in ocfs2 causes special warning code to be > used with KASAN, which produces rather large stack frames: > fs/ocfs2/super.c: In function 'ocfs2_fill_super': > fs/ocfs2/super.c:1219:1: error: the frame size of 3264 bytes is larger than 3072 bytes [-Werror=frame-larger-than=] At least by default it doesn't seem to. gcc 6.2 allyesconfig, CONFIG_KASAN=y with either CONFIG_KASAN_INLINE or CONFIG_KASAN_OUTLINE gcc doesn't emit a stack warning > By simply passing the mask by value instead of reference, we can avoid the > problem completely. Any idea why that's so? > On 64-bit architectures, this is also more efficient, Efficient true, but the same overall stack no? > while on the less common (at least among ocfs2 users) 32-bit architectures, > I'm guessing that the resulting code is comparable to what it was before. > > The current version was introduced by Joe Perches as an optimization, maybe > he can see if my change regresses compared to his. I don't see it. > Cc: Joe Perches > Fixes: 7c2bd2f930ae ("ocfs2: reduce object size of mlog uses") > Signed-off-by: Arnd Bergmann > --- > fs/ocfs2/cluster/masklog.c | 10 +++++----- > fs/o cfs2/cluster/masklog.h | 4 ++-- > 2 files changed, 7 insertions(+), 7 deletions(-) > > diff --git a/fs/ocfs2/cluster/masklog.c b/fs/ocfs2/cluster/masklog.c > index d331c2386b94..9720c5443e4d 100644 > --- a/fs/ocfs2/cluster/masklog.c > +++ b/fs/ocfs2/cluster/masklog.c > @@ -64,7 +64,7 @@ static ssize_t mlog_mask_store(u64 mask, const char *buf, size_t count) > return count; > } > > -void __mlog_printk(const u64 *mask, const char *func, int line, > +void __mlog_printk(const u64 mask, const char *func, int line, > const char *fmt, ...) > { > struct va_format vaf; > @@ -72,14 +72,14 @@ void __mlog_printk(const u64 *mask, const char *func, int line, > const char *level; > const char *prefix = ""; > > - if (!__mlog_test_u64(*mask, mlog_and_bits) || > - __mlog_test_u64(*mask, mlog_not_bits)) > + if (!__mlog_test_u64(mask, mlog_and_bits) || > + __mlog_test_u64(mask, mlog_not_bits)) > return; > > - if (*mask & ML_ERROR) { > + if (mask & ML_ERROR) { > level = KERN_ERR; > prefix = "ERROR: "; > - } else if (*mask & ML_NOTICE) { > + } else if (mask & ML_NOTICE) { > level = KERN_NOTICE; > } else { > level = KERN_INFO; > diff --git a/fs/ocfs2/cluster/masklog.h b/fs/ocfs2/cluster/masklog.h > index 308ea0eb35fd..0d0f4bf2c3d8 100644 > --- a/fs/ocfs2/cluster/masklog.h > +++ b/fs/ocfs2/cluster/masklog.h > @@ -163,7 +163,7 @@ extern struct mlog_bits mlog_and_bits, mlog_not_bits; > #endif > > __printf(4, 5) > -void __mlog_printk(const u64 *m, const char *func, int line, > +void __mlog_printk(const u64 m, const char *func, int line, > const char *fmt, ...); > > /* > @@ -174,7 +174,7 @@ void __mlog_printk(const u64 *m, const char *func, int line, > do { \ > u64 _m = MLOG_MASK_PREFIX | (mask); \ > if (_m & ML_ALLOWED_BITS) \ > - __mlog_printk(&_m, __func__, __LINE__, fmt, \ > + __mlog_printk(_m, __func__, __LINE__, fmt, \ > ##__VA_ARGS__); \ > } while (0) >