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[216.228.121.64]) by mx.google.com with ESMTPS id m199si1122776ybm.111.2019.06.07.18.32.43 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 07 Jun 2019 18:32:43 -0700 (PDT) Received-SPF: pass (google.com: domain of jhubbard@nvidia.com designates 216.228.121.64 as permitted sender) client-ip=216.228.121.64; Authentication-Results: mx.google.com; dkim=pass header.i=@nvidia.com header.s=n1 header.b=GYKNG1gu; spf=pass (google.com: domain of jhubbard@nvidia.com designates 216.228.121.64 as permitted sender) smtp.mailfrom=jhubbard@nvidia.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=nvidia.com Received: from hqpgpgate102.nvidia.com (Not Verified[216.228.121.13]) by hqemgate15.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Fri, 07 Jun 2019 18:32:27 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate102.nvidia.com (PGP Universal service); Fri, 07 Jun 2019 18:32:42 -0700 X-PGP-Universal: processed; by hqpgpgate102.nvidia.com on Fri, 07 Jun 2019 18:32:42 -0700 Received: from [10.110.48.28] (172.20.13.39) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Sat, 8 Jun 2019 01:32:39 +0000 Subject: Re: [PATCH v3 hmm 05/11] mm/hmm: Remove duplicate condition test before wait_event_timeout To: Jason Gunthorpe CC: Jerome Glisse , Ralph Campbell , , , , Andrea Arcangeli , , References: <20190606184438.31646-1-jgg@ziepe.ca> <20190606184438.31646-6-jgg@ziepe.ca> <86962e22-88b1-c1bf-d704-d5a5053fa100@nvidia.com> <20190607133107.GF14802@ziepe.ca> From: John Hubbard Message-ID: <4c1a18b7-6dcb-7ce3-c178-9efd255e8056@nvidia.com> Date: Fri, 7 Jun 2019 18:32:38 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <20190607133107.GF14802@ziepe.ca> X-Originating-IP: [172.20.13.39] X-ClientProxiedBy: HQMAIL103.nvidia.com (172.20.187.11) To HQMAIL107.nvidia.com (172.20.187.13) Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1559957547; bh=xVgyj/Sltl83MtwATtJ5A8fGsNYheaZeYpyqP7L5KAE=; h=X-PGP-Universal:Subject:To:CC:References:From:Message-ID:Date: User-Agent:MIME-Version:In-Reply-To:X-Originating-IP: X-ClientProxiedBy:Content-Type:Content-Language: Content-Transfer-Encoding; b=GYKNG1guS/PHUsAd0J2qN9HUV4d3WKr9M1/GPzqHHGQhrOJ6/d/qZI2z5UvXkDVSn Ng/R0UmHQgBZALpk+QV7PGHkieBLm5sE+nOdT9PnB9vhI0YwIaj7FcafynhrREdkaC LVWTBVe98W53OWJnxbiRTu68ZRBvOMlVxzr34UOPe4fHKZMZJBuyJLUupa6MjR5L+i Vvc7YeCTnOwpFbhUOGQnW0FfnLcky93noaVhM7A3AWMPrAFOWIu7BhzYB1hrF1WCP3 WI5gua45CZvoJhs+zWsNFiKgRpZH45b1dnLmOB/r8OgGpM4n9GPBKWbsM20ZhqCDzl tB81whaCw2vig== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 6/7/19 6:31 AM, Jason Gunthorpe wrote: > The wait_event_timeout macro already tests the condition as its first > action, so there is no reason to open code another version of this, all > that does is skip the might_sleep() debugging in common cases, which is > not helpful. > > Further, based on prior patches, we can now simplify the required condition > test: > - If range is valid memory then so is range->hmm > - If hmm_release() has run then range->valid is set to false > at the same time as dead, so no reason to check both. > - A valid hmm has a valid hmm->mm. > > Allowing the return value of wait_event_timeout() (along with its internal > barriers) to compute the result of the function. > > Signed-off-by: Jason Gunthorpe > --- Reviewed-by: John Hubbard thanks, -- John Hubbard NVIDIA > v3 > - Simplify the wait_event_timeout to not check valid > --- > include/linux/hmm.h | 13 ++----------- > 1 file changed, 2 insertions(+), 11 deletions(-) > > diff --git a/include/linux/hmm.h b/include/linux/hmm.h > index 1d97b6d62c5bcf..26e7c477490c4e 100644 > --- a/include/linux/hmm.h > +++ b/include/linux/hmm.h > @@ -209,17 +209,8 @@ static inline unsigned long hmm_range_page_size(const struct hmm_range *range) > static inline bool hmm_range_wait_until_valid(struct hmm_range *range, > unsigned long timeout) > { > - /* Check if mm is dead ? */ > - if (range->hmm == NULL || range->hmm->dead || range->hmm->mm == NULL) { > - range->valid = false; > - return false; > - } > - if (range->valid) > - return true; > - wait_event_timeout(range->hmm->wq, range->valid || range->hmm->dead, > - msecs_to_jiffies(timeout)); > - /* Return current valid status just in case we get lucky */ > - return range->valid; > + return wait_event_timeout(range->hmm->wq, range->valid, > + msecs_to_jiffies(timeout)) != 0; > } > > /* >