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Wed, 5 Aug 2026 11:16:17 +0000 (GMT) From: Stefan Haberland To: Jens Axboe Cc: linux-block@vger.kernel.org, Jan Hoeppner , linux-s390@vger.kernel.org, Heiko Carstens , Vasily Gorbik , Christian Borntraeger Subject: [PATCH 04/19] s390/dasd: Snapshot intrc before freeing the request block Date: Wed, 5 Aug 2026 13:15:57 +0200 Message-ID: <20260805111612.1285190-5-sth@linux.ibm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260805111612.1285190-1-sth@linux.ibm.com> References: <20260805111612.1285190-1-sth@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: anNSvy9D8ApuPR2i_l9Via0-V0SmqYpS X-Proofpoint-Spam-Info: AW1haW4tMjYwODA1MDA4NiBTYWx0ZWRfX/D1/Gc2ETwjv 66au0DWy6k0fD86xDUy8XCgpHwryb+oew6lkueZkCpRGmXVrQFjTznrwMa+wcApACo+JH7c804A MZP4RXXoHNpI4RWGYVOhyQMc8of+nPg= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODA1MDA4NiBTYWx0ZWRfXycdiq9/UoZbK puOFBpsD570yp5xowBmLqELg1twNjN1h2sGkAqMZmKeP5EzMvHE4gL0MaTfJdw7189VMlo3o/BU FPCEsYOZbE8mAI68m0Ygr1VzDjfN7+Zx1+a61j78e1a6EQbSv3Q+6/ehSlHJz4v9/yQMhk+eah/ 2xKEMYJQDgaOSajtOiXeXA7l/Ygh1V5zGaPFPW5OVOFPkoT2shv1cqMgmkgkmXHnkfITX0mlqsD /eRJmKKhf2Sz2UEUpRvIYFVVzmIK9Vr0UM6HjLWZruxujgmZuF1keDXNXtfI5nNGsNz6FrSOas8 kRACLU8mEZ/Ru7GRKnbMMsMgfNEOVOMPHq2/aFLFLE7JE6sVIju0dXgouZi68zq0GgZoy7RFnal mI26REU5vtX5iIQJgQvp34ZFs0xl7ClQbRG3UGVpm5MR9eXr6pHPTueTVUMcSruwO1nLTn8aDJ6 NS4hPGT+KEUbecj6IFg== X-Proofpoint-GUID: anNSvy9D8ApuPR2i_l9Via0-V0SmqYpS X-Authority-Analysis: v=2.4 cv=KfzidwYD c=1 sm=1 tr=0 ts=6a731b88 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=IkcTkHD0fZMA:10 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VnNF1IyMAAAA:8 a=QORe2UURYKPq8wpwqioA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-05_03,2026-08-04_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 bulkscore=0 impostorscore=0 suspectscore=0 malwarescore=0 adultscore=0 clxscore=1015 priorityscore=1501 phishscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608050086 __dasd_cleanup_cqr() maps the completion result to a block status by reading cqr->intrc, but only after discipline->free_cp() has returned the request block to its memory pool (dasd_eckd_free_cp() ends in dasd_sfree_request()). On SMP another CPU can reallocate that block and overwrite cqr->intrc before it is read, completing the request with the wrong error. proc_bytes is already snapshotted before free_cp() for the same reason; do the same for intrc. Reviewed-by: Jan Höppner Signed-off-by: Stefan Haberland --- drivers/s390/block/dasd.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/s390/block/dasd.c b/drivers/s390/block/dasd.c index 56ef38243f82..34b563917098 100644 --- a/drivers/s390/block/dasd.c +++ b/drivers/s390/block/dasd.c @@ -2699,17 +2699,23 @@ static void __dasd_cleanup_cqr(struct dasd_ccw_req *cqr) struct request *req; blk_status_t error = BLK_STS_OK; unsigned int proc_bytes; - int status; + int status, intrc; req = (struct request *) cqr->callback_data; dasd_profile_end(cqr->block, cqr, req); + /* + * free_cp() returns the request block to its memory pool, so snapshot + * everything still needed from cqr before calling it - another CPU can + * reallocate and overwrite the block right after. + */ proc_bytes = cqr->proc_bytes; + intrc = cqr->intrc; status = cqr->block->base->discipline->free_cp(cqr, req); if (status < 0) error = errno_to_blk_status(status); else if (status == 0) { - switch (cqr->intrc) { + switch (intrc) { case -EPERM: /* * DASD doesn't implement SCSI/NVMe reservations, but it -- 2.53.0