From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by sourceware.org (Postfix) with ESMTPS id E42DA3858434 for ; Thu, 12 May 2022 18:37:39 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org E42DA3858434 Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-544-kgQrqklAOGq-0ge2JqkcOg-1; Thu, 12 May 2022 14:37:36 -0400 X-MC-Unique: kgQrqklAOGq-0ge2JqkcOg-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id E2FA81C04B58; Thu, 12 May 2022 18:37:35 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.39.192.71]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 17C0AC1914E; Thu, 12 May 2022 18:37:34 +0000 (UTC) From: Florian Weimer To: Adhemerval Zanella Cc: libc-alpha@sourceware.org Subject: Re: [PATCH v5 2/2] csu: Implement and use _dl_early_allocate during static startup References: <63d4e062-b5a5-a430-fa56-da09912f1d1a@linaro.org> Date: Thu, 12 May 2022 20:37:33 +0200 In-Reply-To: <63d4e062-b5a5-a430-fa56-da09912f1d1a@linaro.org> (Adhemerval Zanella's message of "Thu, 12 May 2022 10:15:04 -0300") Message-ID: <87lev6siky.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.85 on 10.11.54.8 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-5.6 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, RCVD_IN_DNSWL_LOW, SPF_HELO_NONE, SPF_NONE, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 12 May 2022 18:37:41 -0000 * Adhemerval Zanella: >> +void * >> +_dl_early_allocate (size_t size) >> +{ >> + void *result; >> + >> + if (__curbrk != NULL) >> + /* If the break has been initialized, brk must have run before, >> + so just call it once more. */ >> + { >> + result = __sbrk (size); >> + if (result == (void *) -1) >> + result = NULL; >> + } >> + else >> + { >> + /* If brk has not been invoked, there is no need to update >> + __curbrk. The first call to brk will take care of that. */ >> + void *previous = __brk_call (0); >> + result = __brk_call (previous + size); >> + if (result == previous) >> + result = NULL; >> + else >> + result = previous; >> + } > > Why do you need to avoid update __curbrk here? Otherwise it seems that a > __sbrk() should be suffice here. A subsequent call to _dl_early_allocate would then take the first (sbrk) branch, which may or may not be correct, depending on whether the TCB has been initialized at that point or not. Thanks, Florian