From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2E62D650 for ; Wed, 8 Nov 2023 01:02:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="nt2CDjhJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6DE5CC433C8; Wed, 8 Nov 2023 01:02:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1699405337; bh=YCzRL+kVqkfECP59e1QJcGLwwNjryJJh+Cs7cpeWcEw=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=nt2CDjhJwpkem9VZrZ5m/LnBJWzlcPt0G8R+/J6Om5IQsejFGlYCKYlj6udl4WwCB F2HnU4rmciaUff6HS8zKKGnwGmMcq67t/z78urCReiOgvAQB/1SFfB8qu7PMRWjmTB TObwr9QxHm4BzppdwOwlpc37JwLsGo/oaxlJ8lWFKgRDvZZtzCtOTdQZwAh471oPET 4y0Da5MkH4G5zGOe+aA+mBaZnLdUC2SXDGTnCZZGaC7mHs70bVpniL6aqGjA0AObJl KVext8xhjSbkkhvbpkpZDr9Yt3UW5F8RrEbBNxal1kpzaHhsD71dCxeoQjOuqhkBnQ 9oGT3NFU5cTZQ== Date: Wed, 8 Nov 2023 10:02:10 +0900 From: Masami Hiramatsu (Google) To: "wuqiang.matt" Cc: vgupta@kernel.org, bcain@quicinc.com, jonas@southpole.se, stefan.kristiansson@saunalahti.fi, shorne@gmail.com, geert@linux-m68k.org, andi.shyti@linux.intel.com, mingo@kernel.org, palmer@rivosinc.com, andrzej.hajda@intel.com, arnd@arndb.de, peterz@infradead.orgm, linux-snps-arc@lists.infradead.org, linux-kernel@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-openrisc@vger.kernel.org, linux-trace-kernel@vger.kernel.org, mattwu@163.com, linux@roeck-us.ne Subject: Re: [PATCH v2 1/4] locking/atomic: arc: data size checking in arch_cmpxchg Message-Id: <20231108100210.8118bdfe6fc67317f3638f1c@kernel.org> In-Reply-To: <20231104091615.4884-2-wuqiang.matt@bytedance.com> References: <20231104091615.4884-1-wuqiang.matt@bytedance.com> <20231104091615.4884-2-wuqiang.matt@bytedance.com> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Sat, 4 Nov 2023 17:16:12 +0800 "wuqiang.matt" wrote: > Macro __cmpxchg() renamed to __cmpxchg_32() to emphasize it's explicit > support of 32bit data size, BUILD_BUG_ON() added to avoid any possible > misuses with unsupported data types. > > In case CONFIG_ARC_HAS_LLSC is undefined, arch_cmpxchg() uses spinlock > to accomplish SMP-safety, so the BUILD_BUG_ON checking is uncecessary. > Looks good to me. Reviewed-by: Masami Hiramatsu (Google) > Signed-off-by: wuqiang.matt > --- > arch/arc/include/asm/cmpxchg.h | 12 ++++++------ > 1 file changed, 6 insertions(+), 6 deletions(-) > > diff --git a/arch/arc/include/asm/cmpxchg.h b/arch/arc/include/asm/cmpxchg.h > index e138fde067de..bf46514f6f12 100644 > --- a/arch/arc/include/asm/cmpxchg.h > +++ b/arch/arc/include/asm/cmpxchg.h > @@ -18,14 +18,16 @@ > * if (*ptr == @old) > * *ptr = @new > */ > -#define __cmpxchg(ptr, old, new) \ > +#define __cmpxchg_32(ptr, old, new) \ > ({ \ > __typeof__(*(ptr)) _prev; \ > \ > + BUILD_BUG_ON(sizeof(*(ptr)) != 4); \ > + \ > __asm__ __volatile__( \ > - "1: llock %0, [%1] \n" \ > + "1: llock %0, [%1] \n" \ > " brne %0, %2, 2f \n" \ > - " scond %3, [%1] \n" \ > + " scond %3, [%1] \n" \ > " bnz 1b \n" \ > "2: \n" \ > : "=&r"(_prev) /* Early clobber prevent reg reuse */ \ > @@ -47,7 +49,7 @@ > \ > switch(sizeof((_p_))) { \ > case 4: \ > - _prev_ = __cmpxchg(_p_, _o_, _n_); \ > + _prev_ = __cmpxchg_32(_p_, _o_, _n_); \ > break; \ > default: \ > BUILD_BUG(); \ > @@ -65,8 +67,6 @@ > __typeof__(*(ptr)) _prev_; \ > unsigned long __flags; \ > \ > - BUILD_BUG_ON(sizeof(_p_) != 4); \ > - \ > /* \ > * spin lock/unlock provide the needed smp_mb() before/after \ > */ \ > -- > 2.40.1 > -- Masami Hiramatsu (Google)