From patchwork Fri Aug 2 23:38:04 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Aaron Merey X-Patchwork-Id: 95241 X-Patchwork-Delegate: mark@klomp.org Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 2859D385DDC4 for ; Fri, 2 Aug 2024 23:39:55 +0000 (GMT) X-Original-To: elfutils-devel@sourceware.org Delivered-To: elfutils-devel@sourceware.org Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by sourceware.org (Postfix) with ESMTP id CF2603858D26 for ; Fri, 2 Aug 2024 23:39:27 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org CF2603858D26 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=redhat.com ARC-Filter: OpenARC Filter v1.0.0 sourceware.org CF2603858D26 Authentication-Results: server2.sourceware.org; arc=none smtp.remote-ip=170.10.133.124 ARC-Seal: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1722641969; cv=none; b=i+JbcDiQdJB7oheRDos280qYoMagof6Z0qobWB8gmXSIqC2d0bCmPkxPh8xik72AZOd/pHAK1WKjjyW8bdW7NhZURXfDySFYD9fVoD//tVCd3RclolMTfLrkfv5Ob6StBJKXNgNo1sUOVcPs7xrCluyzxDsJYYCrPVFgksTyLGk= ARC-Message-Signature: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1722641969; c=relaxed/simple; bh=yR9JNBxky28gRJpNDpHNVAbLS4a2ErYy6S5FkkCSOlE=; h=DKIM-Signature:From:To:Subject:Date:Message-ID:MIME-Version; b=GkhjZUQOkqrMhYEqoLiuMR+mF/MD2b60qDgtCW+nI5xPOCGAAQaSy7gL0/AUdzQ3ETfzIup/ikUQExpQq32UoeRfXlr7G3IvrC/fnlFssxlLD+tSUSo10czF7iGQ4vbf7/j/4gltyKIZr8FB7GiTGn7I79M6XvQTVzxFVOYmsIs= ARC-Authentication-Results: i=1; server2.sourceware.org DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1722641967; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Q0MyCOthBD9uI8wdgdzSqJt2p/XMAUgoD5A+SQF2B5A=; b=buF6+lNUVQb0GiMztJdVHnENxs9reYtvORkGo4JllKtiU2SusKgurELAgOYvO2nFBW1S2p jFs2xK2KnCktEFFZ40pThaXHR4IxKb3c3orcM2pI27tN/u+zqgDe4K8EoJ5nG6VWayK2AA 4OF9StXwA2/LvBp1a8IyFAMeM/cC218= Received: from mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-314-Ll_0PwWLPHqkgdPhQKPKBg-1; Fri, 02 Aug 2024 19:39:24 -0400 X-MC-Unique: Ll_0PwWLPHqkgdPhQKPKBg-1 Received: from mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.40]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 48CF219560B1; Fri, 2 Aug 2024 23:39:23 +0000 (UTC) Received: from fedora.redhat.com (unknown [10.22.64.40]) by mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id AF6ED19560AA; Fri, 2 Aug 2024 23:39:21 +0000 (UTC) From: Aaron Merey To: elfutils-devel@sourceware.org Cc: hsm2@rice.edu, johnmc@rice.edu, mark@klomp.org, Aaron Merey Subject: [PATCH 05/10 v3] libdw: make dwarf_getalt and dwarf_setalt thread-safe Date: Fri, 2 Aug 2024 19:38:04 -0400 Message-ID: <20240802233847.690564-5-amerey@redhat.com> In-Reply-To: <20240802233847.690564-1-amerey@redhat.com> References: <20240802233847.690564-1-amerey@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.40 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-Spam-Status: No, score=-11.8 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H4, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_NONE, TXREP 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: elfutils-devel@sourceware.org X-Mailman-Version: 2.1.30 Precedence: list List-Id: Elfutils-devel mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: elfutils-devel-bounces~patchwork=sourceware.org@sourceware.org From: Heather McIntyre * libdw/dwarf_getalt.c (dwarf_getalt): Add locking. * libdw/dwarf_setalt.c (dwarf_setalt): Ditto. Signed-off-by: Heather S. McIntyre Signed-off-by: Aaron Merey Signed-off-by: Mark Wielaard --- v3 changes: Check for NULL argument before acquiring lock. Assign result before releasing lock. Include dwarf_setalt.c changes that were previously included in patch 5/9 v2. libdw/dwarf_getalt.c | 31 +++++++++++++++++++++++++++---- libdw/dwarf_setalt.c | 3 +++ 2 files changed, 30 insertions(+), 4 deletions(-) diff --git a/libdw/dwarf_getalt.c b/libdw/dwarf_getalt.c index 0a12dfae..26433b81 100644 --- a/libdw/dwarf_getalt.c +++ b/libdw/dwarf_getalt.c @@ -160,15 +160,34 @@ find_debug_altlink (Dwarf *dbg) } } +/* find_debug_altlink() modifies "dbg->alt_dwarf". + dwarf_getalt() reads "main->alt_dwarf". + Mutual exclusion is enforced to prevent a race. */ + Dwarf * dwarf_getalt (Dwarf *main) { - /* Only try once. */ - if (main == NULL || main->alt_dwarf == (void *) -1) + if (main == NULL) return NULL; + rwlock_wrlock(main->dwarf_lock); + + /* Only try once. */ + if (main->alt_dwarf == (void *) -1) + { + rwlock_unlock (main->dwarf_lock); + return NULL; + } + + /* Assign result before releasing the lock. */ + Dwarf *result; + if (main->alt_dwarf != NULL) - return main->alt_dwarf; + { + result = main->alt_dwarf; + rwlock_unlock (main->dwarf_lock); + return result; + } find_debug_altlink (main); @@ -176,9 +195,13 @@ dwarf_getalt (Dwarf *main) if (main->alt_dwarf == NULL) { main->alt_dwarf = (void *) -1; + rwlock_unlock (main->dwarf_lock); return NULL; } - return main->alt_dwarf; + result = main->alt_dwarf; + rwlock_unlock (main->dwarf_lock); + + return result; } INTDEF (dwarf_getalt) diff --git a/libdw/dwarf_setalt.c b/libdw/dwarf_setalt.c index dc9b61cb..f98a457c 100644 --- a/libdw/dwarf_setalt.c +++ b/libdw/dwarf_setalt.c @@ -35,6 +35,8 @@ void dwarf_setalt (Dwarf *main, Dwarf *alt) { + rwlock_wrlock (main->dwarf_lock); + if (main->alt_fd != -1) { INTUSE(dwarf_end) (main->alt_dwarf); @@ -43,5 +45,6 @@ dwarf_setalt (Dwarf *main, Dwarf *alt) } main->alt_dwarf = alt; + rwlock_unlock (main->dwarf_lock); } INTDEF (dwarf_setalt)