From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 319FD48C8AE for ; Thu, 8 Oct 2026 09:17:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791451077; cv=none; b=i5Kev7EpbLMGmkU5lcD0z0Dcm590/XzMDxQi9lQc6Fg5t0ZGj1/tNEj9L9TIev5V1WXvzvaBCykOIBMtoXrljqnNSNpRu4eM9zFzjsFqKXYqnfXv6XjNfVPeI6zgZPOM5hjrdaMKDRisbIXvZLOe1zDL2/+ddPUkBp2mPrlL7nA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791451077; c=relaxed/simple; bh=BythzgJZcCsED2Q0dVtAj8TkAWAh4Q0vRRYNVZq7wi8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=UiSlCc2tOByzWYTpWI/lhEThi6kMg2TPcac/BAD2S+Xq32RuIIJaDpti9j2Il5bX0e/+X7CIqudhOSvRBUxHRkZgqaKj5TYdunXWNUGsQAIsCBORjedkAMXBq0HMSPVfd5n6LT+rpZ5I5d/mmNMNi4UtaOOmOSzKWei3Rcde+rk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=C4HJQnHZ; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="C4HJQnHZ" Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 0A3121477; Thu, 8 Oct 2026 02:17:42 -0700 (PDT) Received: from [10.211.55.3] (unknown [10.57.55.7]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0DDD83F959; Thu, 8 Oct 2026 02:17:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1791451065; bh=BythzgJZcCsED2Q0dVtAj8TkAWAh4Q0vRRYNVZq7wi8=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=C4HJQnHZA+/S0SAYFkSRCDzEWC0XS1yVIvox5ZhV0zkchd1+inr9I9jZSEyjrQZrP 2Kaa1b8L1T7/yFaJ2sPVT3jKJqDcLhQTf5PkJgj1Tp38m/fjOWckzEbz3WIBPZeBMk lqfnAo95OEYylCQitjOkr5e03w61sDRZ8hr7ZMoc= Message-ID: <7490d5e6-ac9b-4f23-b58d-60eec2882e60@arm.com> Date: Thu, 8 Oct 2026 10:17:33 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Thunderbird Daily Subject: Re: [PATCH] arm_mpam: make the mon_sel guard conditional only To: Sasha Levin , James Morse , Nathan Chancellor , Jonathan Cameron , Andre Przywara , Gavin Shan Cc: "kernelci.org bot" , Reinette Chatre , Fenghua Yu , Nick Desaulniers , Bill Wendling , Justin Stitt , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev References: <20261003121251.3942666-1-sashal@kernel.org> Content-Language: en-US From: Ben Horgan In-Reply-To: <20261003121251.3942666-1-sashal@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Sasha, Thanks for the report and fix. On 03/10/2026 13:12, Sasha Levin wrote: > Building arm64 allmodconfig with clang fails: > > drivers/resctrl/mpam_internal.h:207:7: error: ignoring return value > of function declared with 'warn_unused_result' attribute > [-Werror,-Wunused-result] > 207 | mpam_mon_sel_lock(_T), mpam_mon_sel_unlock(_T)); > > mpam_mon_sel_lock() is __must_check and can fail: for an MSC accessed > through the MPAM-Fb firmware interface it returns false when called > from a context that cannot sleep. The mon_sel guard was defined with > DEFINE_GUARD(), which calls it unconditionally and discards the > result, so a guard(mon_sel) user would carry on without the lock and > release it on scope exit. The unconditional guard only exists as the > base for the conditional mon_sel_lock variant, which is the one > actually used. > > Define mon_sel_lock directly as a conditional guard class instead, as > posix-timers does for lock_timer: the constructor returns NULL when > the lock cannot be taken, and the destructor only releases a lock > that was taken. ACQUIRE(mon_sel_lock, ...) works as before, including > ACQUIRE_ERR() returning -EBUSY on failure, and there is no > unconditional variant left to misuse. > > Reported-by: kernelci.org bot > Closes: https://d.kernelci.org/i/maestro:66f869ecbbb5b8592562ffd89f049c5ddf682547 > Closes: https://d.kernelci.org/i/maestro:647269216758644837afcaac8e67d8dbe713a0e2 > Fixes: 0db1715e4c9c ("arm_mpam: propagate MSC access errors for hw_probe functions") > Assisted-by: LLM > Signed-off-by: Sasha Levin > --- > drivers/resctrl/mpam_internal.h | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_internal.h > index ee7c3953a9b6c..be1795b29aca2 100644 > --- a/drivers/resctrl/mpam_internal.h > +++ b/drivers/resctrl/mpam_internal.h > @@ -203,9 +203,10 @@ static inline int mpam_mon_sel_lock_init(struct device *dev, > return devm_mutex_init(dev, &msc->mon_sel_mutex); > } > > -DEFINE_GUARD(mon_sel, struct mpam_msc *, > - mpam_mon_sel_lock(_T), mpam_mon_sel_unlock(_T)); > -DEFINE_GUARD_COND(mon_sel, _lock, mpam_mon_sel_lock(_T), _RET); > +DEFINE_CLASS(mon_sel_lock, struct mpam_msc *, > + _T ? mpam_mon_sel_unlock(_T) : (void)0, Could this line be an if statement? That looks to be common in other users of DEFINE_CLASS(). if (_T) mpam_mon_sel_unlock(_T) Thanks, Ben > + mpam_mon_sel_lock(msc) ? msc : NULL, struct mpam_msc *msc); > +DEFINE_CLASS_IS_COND_GUARD(mon_sel_lock); > > /* Bits for mpam features bitmaps */ > enum mpam_device_features {