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Mon, 09 Nov 2026 03:32:01 +0000 (GMT) Received: from smtpav05.fra02v.mail.ibm.com (smtpav05.fra02v.mail.ibm.com [10.20.54.104]) by smtprelay03.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 6A93VvrR46203186 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 9 Nov 2026 03:31:57 GMT Received: from smtpav05.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 7DF3E20043; Mon, 9 Nov 2026 03:31:57 +0000 (GMT) Received: from smtpav05.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 0331820040; Mon, 9 Nov 2026 03:31:51 +0000 (GMT) Received: from li-a84c74cc-2b13-11b2-a85c-acdd023f0674.ibm.com.com (unknown [9.61.101.130]) by smtpav05.fra02v.mail.ibm.com (Postfix) with ESMTP; Mon, 9 Nov 2026 03:31:49 +0000 (GMT) From: Nilay Shroff To: kbusch@kernel.org, hch@lst.de, sagi@grimberg.me, axboe@kernel.dk, chaitanyak@nvidia.com Cc: gjoyce@linux.ibm.com, bvanassche@acm.org, elver@google.com, linux-nvme@lists.infradead.org, Nilay Shroff Subject: [PATCH 05/23] nvmet: add context annotation for nvmet_ns::readonly Date: Mon, 9 Nov 2026 08:58:10 +0530 Message-ID: <20261109033102.982191-30-nilay@linux.ibm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261109033102.982191-25-nilay@linux.ibm.com> References: <20261109033102.982191-25-nilay@linux.ibm.com> X-Archived-By: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Info: AW1haW4tMjYxMTA5MDAxMiBTYWx0ZWRfX3TPf5z/tkC3f twlLg7oBkgeCjy5Se8zUGG0eD8zLJ7+o0muU0EcBAIwSQujr+XHGW5OmiB4RxTnMmcSkiUXgTlw sXYLeKb8SrSDNrSjlOB/xDLLyD2a2y0= X-Authority-Analysis: v=2.4 cv=GISdgeNK c=1 sm=1 tr=0 ts=6af13eb2 cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=zJRp6_cAMcgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VnNF1IyMAAAA:8 a=uYnn4NJ3HOK8bXenDcAA:9 X-Proofpoint-GUID: rCIQCqRxzR-z72pwYXzkbLdLry07Nwc0 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMTA5MDAxMiBTYWx0ZWRfX6JRdLG/suN+O 7SwIG6JkRsDfXZRwHQF8BVF0BOB+gJQXt284gyWYFL+HEntnydqmMtzeV5dVBKvO1cBcVWOrGXa PoZ7bPh1f9/i4abuaAM8JH8SJbvRHs7C6+1XOXVajAw0CKMJ7ig5popsG41su8xFWYb1Stlgu4v TyjvS4ydPjTMOJ1KCCXOD1A1Oo/guw8KlDq3sYZXy+NY/4A4Y0OW0b2rvG0fIIIA7WArLqtcDhR wjKHtOZf6vs78j/A7LSR/GzuqcwwPxlqTt7qTqlPTp0qABF0wEErAVDKsYuGH0lA2Fl3/ZMUHOZ 3sEy9m8VzUMMHDodKX1ewHSOgV8tzxTd/5Ku/KYWyv051kFbeoiabB0HVa12akgZ54bvTsj0qeZ qOX6jbd133M/DrXOZwVYfMHoW2i5EhqfvC+3hFM3D1hGyghw/xeehie/CBjt3sV8J5Jwc8Qi33/ dkIHAi/kLwRkK21ae6A== X-Proofpoint-ORIG-GUID: 7SIvo18I8rxp0TZF8WV7hsHIRGMj2CW8 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.138,FMLib:17.12.100.49 definitions=2026-11-09_01,2026-11-06_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 bulkscore=0 impostorscore=0 clxscore=1015 adultscore=0 priorityscore=1501 phishscore=0 spamscore=0 malwarescore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2611040001 definitions=main-2611090012 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261108_193221_961415_1F50F1AF X-CRM114-Status: GOOD ( 20.42 ) X-Spam-Score: -2.6 (--) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" X-Spam-Status: No, score=-16.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_EF,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 The nvmet_ns::readonly field is protected by nvmet_subsys::lock. Annotate it with __guarded_by(&subsys->lock) to allow the Clang context analyzer to validate accesses to this field. The admin command handlers nvmet_get_feat_write_protect() and nvmet_set_feat_write_protect() access nvmet_ns::readonly while holding ns->subsys->lock. However, the context analyzer cannot recognize that subsys->lock and ns->subsys->lock refer to the same mutex. Use ns->subsys->lock directly in these functions to avoid false positive warnings. The I/O hotpath functions, nvmet_execute_identify_ns(), nvmet_execute_id_cs_indep() and nvmet_io_cmd_check_access(), read nvmet_ns::readonly without holding the lock. These lockless reads may race with updates to the field, potentially observing a transient value. Such races are acceptable for these accesses. Introduce nvmet_ns_readonly() to perform these lockless reads using data_race(READ_ONCE()). This suppresses KCSAN reports for the intentional races and informs the context analyzer that the access is intentionally performed without holding the lock. Use WRITE_ONCE() for updates to nvmet_ns::readonly in nvmet_set_feat_write_protect() to pair with the lockless READ_ONCE() accesses. Signed-off-by: Nilay Shroff --- drivers/nvme/target/admin-cmd.c | 15 +++++++-------- drivers/nvme/target/core.c | 2 +- drivers/nvme/target/nvmet.h | 16 +++++++++++++++- 3 files changed, 23 insertions(+), 10 deletions(-) diff --git a/drivers/nvme/target/admin-cmd.c b/drivers/nvme/target/admin-cmd.c index 517f8cc78473..6b0ba383106d 100644 --- a/drivers/nvme/target/admin-cmd.c +++ b/drivers/nvme/target/admin-cmd.c @@ -938,7 +938,7 @@ static void nvmet_execute_identify_ns(struct nvmet_req *req) id->lbaf[0].ms = cpu_to_le16(req->ns->metadata_size); } - if (req->ns->readonly) + if (nvmet_ns_readonly(req->ns)) id->nsattr |= NVME_NS_ATTR_RO; done: if (!status) @@ -1133,7 +1133,7 @@ static void nvmet_execute_id_cs_indep(struct nvmet_req *req) id->nstat = NVME_NSTAT_NRDY; id->anagrpid = cpu_to_le32(req->ns->anagrpid); id->nmic = NVME_NS_NMIC_SHARED; - if (req->ns->readonly) + if (nvmet_ns_readonly(req->ns)) id->nsattr |= NVME_NS_ATTR_RO; if (nvmet_ns_bdev(req->ns) && bdev_rot(nvmet_ns_bdev(req->ns))) id->nsfeat |= NVME_NS_ROTATIONAL; @@ -1255,13 +1255,13 @@ static u16 nvmet_set_feat_write_protect(struct nvmet_req *req) mutex_lock(&req->ns->subsys->lock); switch (write_protect) { case NVME_NS_WRITE_PROTECT: - req->ns->readonly = true; + WRITE_ONCE(req->ns->readonly, true); status = nvmet_write_protect_flush_sync(req); if (status) - req->ns->readonly = false; + WRITE_ONCE(req->ns->readonly, false); break; case NVME_NS_NO_WRITE_PROTECT: - req->ns->readonly = false; + WRITE_ONCE(req->ns->readonly, false); status = 0; break; default: @@ -1451,20 +1451,19 @@ void nvmet_execute_set_features(struct nvmet_req *req) static u16 nvmet_get_feat_write_protect(struct nvmet_req *req) { - struct nvmet_subsys *subsys = nvmet_req_subsys(req); u32 result; result = nvmet_req_find_ns(req); if (result) return result; - mutex_lock(&subsys->lock); + mutex_lock(&req->ns->subsys->lock); if (req->ns->readonly == true) result = NVME_NS_WRITE_PROTECT; else result = NVME_NS_NO_WRITE_PROTECT; nvmet_set_result(req, result); - mutex_unlock(&subsys->lock); + mutex_unlock(&req->ns->subsys->lock); return 0; } diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c index ef99c45f0f37..116b1b500790 100644 --- a/drivers/nvme/target/core.c +++ b/drivers/nvme/target/core.c @@ -1090,7 +1090,7 @@ static inline u16 nvmet_check_ana_state(struct nvmet_port *port, static inline u16 nvmet_io_cmd_check_access(struct nvmet_req *req) { - if (unlikely(req->ns->readonly)) { + if (unlikely(nvmet_ns_readonly(req->ns))) { switch (req->cmd->common.opcode) { case nvme_cmd_read: case nvme_cmd_flush: diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h index b63664250ef4..b76671672aca 100644 --- a/drivers/nvme/target/nvmet.h +++ b/drivers/nvme/target/nvmet.h @@ -155,7 +155,8 @@ struct nvmet_ns { __guarded_by(&subsys->lock); struct file *file __guarded_by(&subsys->lock); - bool readonly; + bool readonly + __guarded_by(&subsys->lock); u32 nsid; u32 blksize_shift; loff_t size; @@ -205,6 +206,19 @@ static inline _type nvmet_ns_##_name(struct nvmet_ns *ns) \ NVMET_NS_ACCESSOR(struct block_device *, bdev) NVMET_NS_ACCESSOR(struct file *, file) +/* + * These accessors use data_race() and READ_ONCE() to allow lockless access to + * the corresponding fields. Use them only in code paths where a concurrent + * update to the field is harmless and the resulting data race is acceptable. + */ +#define NVMET_NS_ACCESSOR_RACE(_type, _name) \ +static inline _type nvmet_ns_##_name(struct nvmet_ns *ns) \ +{ \ + return data_race(READ_ONCE(ns->_name)); \ +} \ + +NVMET_NS_ACCESSOR_RACE(bool, readonly) + static inline struct nvmet_ns *to_nvmet_ns(struct config_item *item) { return container_of(to_config_group(item), struct nvmet_ns, group); -- 2.53.0