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[88.208.79.100]) by smtp.gmail.com with ESMTPSA id z9sm32619727wmg.46.2020.09.08.05.24.56 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 08 Sep 2020 05:24:57 -0700 (PDT) Sender: Michal Meloun Reply-To: meloun.michal@gmail.com Subject: Re: svn commit: r365445 - head/sys/cam/mmc To: Andriy Gapon , src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org References: <202009080546.0885kAgk006783@repo.freebsd.org> <34826ee7-12a9-d309-1fee-cd2e95744603@FreeBSD.org> From: Michal Meloun Message-ID: <67be7fa5-30dd-b7ee-1076-9c29195d83d3@gmail.com> Date: Tue, 8 Sep 2020 14:24:59 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <34826ee7-12a9-d309-1fee-cd2e95744603@FreeBSD.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 4Bm4983Lm7z4fx4 X-Spamd-Bar: -- Authentication-Results: mx1.freebsd.org; dkim=pass header.d=gmail.com header.s=20161025 header.b=o3zss6EI; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (mx1.freebsd.org: domain of melounmichal@gmail.com designates 2a00:1450:4864:20::444 as permitted sender) smtp.mailfrom=melounmichal@gmail.com X-Spamd-Result: default: False [-2.54 / 15.00]; HAS_REPLYTO(0.00)[meloun.michal@gmail.com]; RCVD_VIA_SMTP_AUTH(0.00)[]; TO_DN_SOME(0.00)[]; R_SPF_ALLOW(-0.20)[+ip6:2a00:1450:4000::/36:c]; FREEMAIL_FROM(0.00)[gmail.com]; RCVD_COUNT_THREE(0.00)[3]; DKIM_TRACE(0.00)[gmail.com:+]; DMARC_POLICY_ALLOW(-0.50)[gmail.com,none]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; FREEMAIL_ENVFROM(0.00)[gmail.com]; ASN(0.00)[asn:15169, ipnet:2a00:1450::/32, country:US]; MID_RHS_MATCH_FROM(0.00)[]; TAGGED_FROM(0.00)[]; DWL_DNSWL_NONE(0.00)[gmail.com:dkim]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-0.99)[-0.990]; R_DKIM_ALLOW(-0.20)[gmail.com:s=20161025]; FROM_HAS_DN(0.00)[]; RCPT_COUNT_THREE(0.00)[4]; TO_MATCH_ENVRCPT_ALL(0.00)[]; NEURAL_HAM_LONG(-1.00)[-0.998]; MIME_GOOD(-0.10)[text/plain]; FREEMAIL_REPLYTO(0.00)[gmail.com]; REPLYTO_DOM_EQ_FROM_DOM(0.00)[]; NEURAL_SPAM_SHORT(0.45)[0.451]; RCVD_IN_DNSWL_NONE(0.00)[2a00:1450:4864:20::444:from]; RCVD_TLS_ALL(0.00)[]; MAILMAN_DEST(0.00)[svn-src-head,svn-src-all] X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.33 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 08 Sep 2020 12:25:01 -0000 On 08.09.2020 9:10, Andriy Gapon wrote: > On 08/09/2020 08:46, Andriy Gapon wrote: >> Author: avg >> Date: Tue Sep 8 05:46:10 2020 >> New Revision: 365445 >> URL: https://svnweb.freebsd.org/changeset/base/365445 >> >> Log: >> mmc_da: make sure that part_index is not used uninitialized in sddastart > [snip] >> Modified: head/sys/cam/mmc/mmc_da.c >> ============================================================================== >> --- head/sys/cam/mmc/mmc_da.c Tue Sep 8 04:44:37 2020 (r365444) >> +++ head/sys/cam/mmc/mmc_da.c Tue Sep 8 05:46:10 2020 (r365445) >> @@ -1808,6 +1808,7 @@ sddastart(struct cam_periph *periph, union ccb *start_ >> } >> >> /* Find partition that has outstanding commands. Prefer current partition. */ >> + part_index = softc->part_curr; >> part = softc->part[softc->part_curr]; >> bp = bioq_first(&part->bio_queue); >> if (bp == NULL) { >> > > One thing that concerns me is that it was obvious (to a human) that part_index > could be used uninitialized if bp was not NULL. > Yet, there was no warning or error from the compiler when I built that code for > armv7. > > I wonder if we disable some relevant warnings for that architecture. > Or if the compiler (clang 11) could not figure that out. > Hmm, for this in kernel code : int foo(void); int foo(void) { int rv; return (rv); } warning is reported for both armv7 and arm64 for native or cross compile. It seems that clang11 doesn't emit warnings only for more complicated cases... I writing this because i just found another usage of uninitialized variable, in this case in much more complicated abort_handler() function in arm/trap-v6.c again without warning emitted. Michal