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a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1622647106; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=CkKo+yzVGk8lM2cESfddW3qeWJPQwIy6aUzSH9Y2z7U=; b=gs/UPcvlE9iqCShMwnhP3HOqy2w39Ncv+ztuvTT03hkmVfLtUyOf2E29mNRxsYosULtcvP BCcL0xOpiKZ/eIoALz29vWBB5vnPtD1eFSUV/3m21U+9+lHsI/jJ+RIEGtKgEjyUBkvVff fz+fQRabkEMh5ZGd8CjtF2oDqFPEbbk= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1622635746; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=CkKo+yzVGk8lM2cESfddW3qeWJPQwIy6aUzSH9Y2z7U=; b=JXtMKXRsAJ0k3fJE/rumTkKd7hzNtbf5WBNYLEgt31PVX0mW31YkYzX5dTGys/kA8MSCXf MTbnQeoKme4/4EOegTIH26a/fNnM5e6P5sZ7KPGaHjapghWQkZoEpPj/CTf4j6DchCTi+t hS+6qTVroYHwJnVI195gh2Ak29vTKN0= Subject: Re: [PATCH v20210601 09/38] tools/guest: prepare to allocate arrays once To: Olaf Hering Cc: xen-devel@lists.xenproject.org, Ian Jackson , Wei Liu References: <20210601161118.18986-1-olaf@aepfle.de> <20210601161118.18986-10-olaf@aepfle.de> <531fe9c5-aa7f-be99-5d78-85d817139740@suse.com> <20210602140305.39eb417a.olaf@aepfle.de> From: Juergen Gross Message-ID: Date: Wed, 2 Jun 2021 14:09:05 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.0 MIME-Version: 1.0 In-Reply-To: <20210602140305.39eb417a.olaf@aepfle.de> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="xQnFj3m4T8DHdlYxNoMyCYPGj5P711fT7" This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --xQnFj3m4T8DHdlYxNoMyCYPGj5P711fT7 Content-Type: multipart/mixed; boundary="wfXRgoU485kj4IBWXcwXSIEQd0GPrusRg"; protected-headers="v1" From: Juergen Gross To: Olaf Hering Cc: xen-devel@lists.xenproject.org, Ian Jackson , Wei Liu Message-ID: Subject: Re: [PATCH v20210601 09/38] tools/guest: prepare to allocate arrays once References: <20210601161118.18986-1-olaf@aepfle.de> <20210601161118.18986-10-olaf@aepfle.de> <531fe9c5-aa7f-be99-5d78-85d817139740@suse.com> <20210602140305.39eb417a.olaf@aepfle.de> In-Reply-To: <20210602140305.39eb417a.olaf@aepfle.de> --wfXRgoU485kj4IBWXcwXSIEQd0GPrusRg Content-Type: multipart/mixed; boundary="------------4865E6143B74DF93E1BDA534" Content-Language: en-US This is a multi-part message in MIME format. --------------4865E6143B74DF93E1BDA534 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: quoted-printable On 02.06.21 14:03, Olaf Hering wrote: > Am Wed, 2 Jun 2021 09:29:08 +0200 > schrieb Juergen Gross : >=20 >>> + ctx->restore.m =3D malloc(sizeof(*ctx->restore.m)); >>> + if ( !ctx->restore.m ) { >> >> ... this case might trigger without the full series applied, due to >> allocating zero bytes (same for the save side below). >=20 > Such bisection point with a libc that returns NULL would be just bad lu= ck. Sure, but sending a patch which is known to break bisecting is bad behavior. You could even add a dummy element (with a comment indicating its purpose) which could be removed when the first "real" structure element is being added. > See git-bisect(1) "Avoiding testing a commit" how to deal with it, in t= he unlikely case it actually triggers. It can be avoided, yes, but you need to search for the reason the failure occurred first. And this debugging effort should be avoided if possible. 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