From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 773AAC4332F for ; Wed, 14 Dec 2022 13:57:33 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1p5S6D-0006N9-52; Wed, 14 Dec 2022 08:47:05 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1p5S5C-0004v6-NX for qemu-devel@nongnu.org; Wed, 14 Dec 2022 08:46:02 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1p5S5A-0003lF-Te for qemu-devel@nongnu.org; Wed, 14 Dec 2022 08:46:02 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1671025560; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=PcZY0YEij9vXG3pq/kdynWi4bBLP6h43ygUupcJ4V8Q=; b=iIL1DTby9TdNL6t0p4ujkPCQD1SYGymPfeJ+ix6jaIxqxbx/jOBASy7yxaQ09MuEvNU5yd mv4TqNmBNJMfgO/2RIQwwoNZ01QvNlvez29308kwZ5VYjUcG5UKeNzoTYUh7LZqQxkKMIb P4zEH9KZmMOYFuOWrJ/A74RnCVo6Aqc= 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-222-WeML844SOGaZ1RFELZ3mUA-1; Wed, 14 Dec 2022 08:45:55 -0500 X-MC-Unique: WeML844SOGaZ1RFELZ3mUA-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 32F693C1068A; Wed, 14 Dec 2022 13:45:55 +0000 (UTC) Received: from merkur.redhat.com (unknown [10.39.194.243]) by smtp.corp.redhat.com (Postfix) with ESMTP id 72B9414171BE; Wed, 14 Dec 2022 13:45:54 +0000 (UTC) From: Kevin Wolf To: qemu-block@nongnu.org Cc: kwolf@redhat.com, peter.maydell@linaro.org, qemu-devel@nongnu.org Subject: [PULL 47/51] graph-lock: TSA annotations for lock/unlock functions Date: Wed, 14 Dec 2022 14:44:49 +0100 Message-Id: <20221214134453.31665-48-kwolf@redhat.com> In-Reply-To: <20221214134453.31665-1-kwolf@redhat.com> References: <20221214134453.31665-1-kwolf@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.7 Received-SPF: pass client-ip=170.10.133.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Signed-off-by: Kevin Wolf Message-Id: <20221207131838.239125-15-kwolf@redhat.com> Reviewed-by: Emanuele Giuseppe Esposito Signed-off-by: Kevin Wolf --- include/block/graph-lock.h | 80 +++++++++++++++++++++++++++++++++----- block/graph-lock.c | 3 ++ 2 files changed, 73 insertions(+), 10 deletions(-) diff --git a/include/block/graph-lock.h b/include/block/graph-lock.h index 85e8a53b73..50b7e7b1b6 100644 --- a/include/block/graph-lock.h +++ b/include/block/graph-lock.h @@ -21,6 +21,7 @@ #define GRAPH_LOCK_H #include "qemu/osdep.h" +#include "qemu/clang-tsa.h" #include "qemu/coroutine.h" @@ -57,6 +58,35 @@ */ typedef struct BdrvGraphRWlock BdrvGraphRWlock; +/* Dummy lock object to use for Thread Safety Analysis (TSA) */ +typedef struct TSA_CAPABILITY("graph-lock") BdrvGraphLock { +} BdrvGraphLock; + +extern BdrvGraphLock graph_lock; + +/* + * clang doesn't check consistency in locking annotations between forward + * declarations and the function definition. Having the annotation on the + * definition, but not the declaration in a header file, may give the reader + * a false sense of security because the condition actually remains unchecked + * for callers in other source files. + * + * Therefore, as a convention, for public functions, GRAPH_RDLOCK and + * GRAPH_WRLOCK annotations should be present only in the header file. + */ +#define GRAPH_WRLOCK TSA_REQUIRES(graph_lock) +#define GRAPH_RDLOCK TSA_REQUIRES_SHARED(graph_lock) + +/* + * TSA annotations are not part of function types, so checks are defeated when + * using a function pointer. As a workaround, annotate function pointers with + * this macro that will require that the lock is at least taken while reading + * the pointer. In most cases this is equivalent to actually protecting the + * function call. + */ +#define GRAPH_RDLOCK_PTR TSA_GUARDED_BY(graph_lock) +#define GRAPH_WRLOCK_PTR TSA_GUARDED_BY(graph_lock) + /* * register_aiocontext: * Add AioContext @ctx to the list of AioContext. @@ -85,14 +115,14 @@ void unregister_aiocontext(AioContext *ctx); * This function polls. Callers must not hold the lock of any AioContext other * than the current one. */ -void bdrv_graph_wrlock(void); +void bdrv_graph_wrlock(void) TSA_ACQUIRE(graph_lock) TSA_NO_TSA; /* * bdrv_graph_wrunlock: * Write finished, reset global has_writer to 0 and restart * all readers that are waiting. */ -void bdrv_graph_wrunlock(void); +void bdrv_graph_wrunlock(void) TSA_RELEASE(graph_lock) TSA_NO_TSA; /* * bdrv_graph_co_rdlock: @@ -116,7 +146,8 @@ void bdrv_graph_wrunlock(void); * loop) to take it and wait that the coroutine ends, so that * we always signal that a reader is running. */ -void coroutine_fn bdrv_graph_co_rdlock(void); +void coroutine_fn TSA_ACQUIRE_SHARED(graph_lock) TSA_NO_TSA +bdrv_graph_co_rdlock(void); /* * bdrv_graph_rdunlock: @@ -124,7 +155,8 @@ void coroutine_fn bdrv_graph_co_rdlock(void); * If the writer is waiting for reads to finish (has_writer == 1), signal * the writer that we are done via aio_wait_kick() to let it continue. */ -void coroutine_fn bdrv_graph_co_rdunlock(void); +void coroutine_fn TSA_RELEASE_SHARED(graph_lock) TSA_NO_TSA +bdrv_graph_co_rdunlock(void); /* * bdrv_graph_rd{un}lock_main_loop: @@ -132,8 +164,11 @@ void coroutine_fn bdrv_graph_co_rdunlock(void); * in the main loop. It is just asserting that we are not * in a coroutine and in GLOBAL_STATE_CODE. */ -void bdrv_graph_rdlock_main_loop(void); -void bdrv_graph_rdunlock_main_loop(void); +void TSA_ACQUIRE_SHARED(graph_lock) TSA_NO_TSA +bdrv_graph_rdlock_main_loop(void); + +void TSA_RELEASE_SHARED(graph_lock) TSA_NO_TSA +bdrv_graph_rdunlock_main_loop(void); /* * assert_bdrv_graph_readable: @@ -150,6 +185,17 @@ void assert_bdrv_graph_readable(void); */ void assert_bdrv_graph_writable(void); +/* + * Calling this function tells TSA that we know that the lock is effectively + * taken even though we cannot prove it (yet) with GRAPH_RDLOCK. This can be + * useful in intermediate stages of a conversion to using the GRAPH_RDLOCK + * macro. + */ +static inline void TSA_ASSERT_SHARED(graph_lock) TSA_NO_TSA +assume_graph_lock(void) +{ +} + typedef struct GraphLockable { } GraphLockable; /* @@ -159,13 +205,21 @@ typedef struct GraphLockable { } GraphLockable; */ #define GML_OBJ_() (&(GraphLockable) { }) -static inline GraphLockable *graph_lockable_auto_lock(GraphLockable *x) +/* + * This is not marked as TSA_ACQUIRE() because TSA doesn't understand the + * cleanup attribute and would therefore complain that the graph is never + * unlocked. TSA_ASSERT() makes sure that the following calls know that we + * hold the lock while unlocking is left unchecked. + */ +static inline GraphLockable * TSA_ASSERT(graph_lock) TSA_NO_TSA +graph_lockable_auto_lock(GraphLockable *x) { bdrv_graph_co_rdlock(); return x; } -static inline void graph_lockable_auto_unlock(GraphLockable *x) +static inline void TSA_NO_TSA +graph_lockable_auto_unlock(GraphLockable *x) { bdrv_graph_co_rdunlock(); } @@ -195,14 +249,20 @@ typedef struct GraphLockableMainloop { } GraphLockableMainloop; */ #define GMLML_OBJ_() (&(GraphLockableMainloop) { }) -static inline GraphLockableMainloop * +/* + * This is not marked as TSA_ACQUIRE() because TSA doesn't understand the + * cleanup attribute and would therefore complain that the graph is never + * unlocked. TSA_ASSERT() makes sure that the following calls know that we + * hold the lock while unlocking is left unchecked. + */ +static inline GraphLockableMainloop * TSA_ASSERT(graph_lock) TSA_NO_TSA graph_lockable_auto_lock_mainloop(GraphLockableMainloop *x) { bdrv_graph_rdlock_main_loop(); return x; } -static inline void +static inline void TSA_NO_TSA graph_lockable_auto_unlock_mainloop(GraphLockableMainloop *x) { bdrv_graph_rdunlock_main_loop(); diff --git a/block/graph-lock.c b/block/graph-lock.c index c4d9d2c274..454c31e691 100644 --- a/block/graph-lock.c +++ b/block/graph-lock.c @@ -24,6 +24,9 @@ #include "block/block.h" #include "block/block_int.h" +/* Dummy lock object to use for Thread Safety Analysis (TSA) */ +BdrvGraphLock graph_lock; + /* Protects the list of aiocontext and orphaned_reader_count */ static QemuMutex aio_context_list_lock; -- 2.38.1