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Tue, 04 Aug 2026 01:30:32 -0700 (PDT) Received: from google.com ([2a00:79e0:2031:6:32eb:b46b:e9eb:65c5]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-38feda512fesm959039a91.9.2026.08.04.01.30.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 04 Aug 2026 01:30:32 -0700 (PDT) Date: Tue, 4 Aug 2026 17:30:27 +0900 From: Sergey Senozhatsky To: haoqin huang Cc: Sergey Senozhatsky , Minchan Kim , Jens Axboe , Nick Terrell , David Sterba , Andrew Morton , linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, Haoqin Huang , Rongwei Wang Subject: Re: [PATCH v5 3/4] zram: validate parameters in each backend's setup_params Message-ID: References: <20260730060133.80233-1-haoqinhuang7@gmail.com> <20260803141256.60599-1-haoqinhuang7@gmail.com> <20260803141256.60599-4-haoqinhuang7@gmail.com> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On (26/08/04 15:02), haoqin huang wrote: > On Tue, Aug 4, 2026 at 1:37 PM Sergey Senozhatsky > wrote: > > > > On (26/08/03 22:12), Haoqin Huang wrote: > > > static int deflate_setup_params(struct zcomp_params *params) > > > { > > > + if (params->dict_sz) { > > > + pr_err("deflate: dictionary is not supported\n"); > > > + return -EOPNOTSUPP; > > > + } > > > + > > > if (params->level == ZCOMP_PARAM_NOT_SET) > > > params->level = Z_DEFAULT_COMPRESSION; > > > > If we want to be pedantic, then {} should also be added to the "if" > > in this case. And in other similar cases. > > > > Okay, thanks for the reminder. I will add {} to the if-branch for consistency. Thanks. > > > + else if (params->level < Z_DEFAULT_COMPRESSION || > > > + params->level > Z_BEST_COMPRESSION) { > > > + pr_err("deflate: invalid compression level %d\n", params->level); > > > + return -EINVAL; > > > + } > > > + > > > > [..] > > > + else if (params->level < 1 || params->level > LZ4HC_MAX_CLEVEL) { > > > + pr_err("lz4hc: invalid compression level %d\n", params->level); > > > + return -EINVAL; > > > + } > > > > Let's add a small comment justifying/explaining that "1" constant? > > For the lz4hc comment, how about: > /* > * LZ4HC_compress_generic() clamps levels below 1 to > * LZ4HC_DEFAULT_CLEVEL, so < 1 is the real lower bound. > */ > Does that look reasonable? I suppose we want to document the fact that LZ4HC_MIN_CLEVEL (which would be naturally expected here) is set to 3 and cuts off levels 1 and 2 which are perfectly valid. Maybe just say something like that, for simplicity.