From: Dexuan Cui <decui@microsoft.com>
To: kys@microsoft.com, sthemmin@microsoft.com, wei.liu@kernel.org,
jejb@linux.ibm.com, martin.petersen@oracle.com,
haiyangz@microsoft.com, ming.lei@redhat.com, bvanassche@acm.org,
john.garry@huawei.com, linux-scsi@vger.kernel.org,
linux-hyperv@vger.kernel.org, longli@microsoft.com,
mikelley@microsoft.com
Cc: linux-kernel@vger.kernel.org, Dexuan Cui <decui@microsoft.com>,
stable@vger.kernel.org
Subject: [PATCH v2] scsi: core: Fix shost->cmd_per_lun calculation in scsi_add_host_with_dma()
Date: Thu, 7 Oct 2021 10:49:57 -0700 [thread overview]
Message-ID: <20211007174957.2080-1-decui@microsoft.com> (raw)
After commit ea2f0f77538c, a 416-CPU VM running on Hyper-V hangs during
boot because scsi_add_host_with_dma() sets shost->cmd_per_lun to a
negative number (the below numbers may differ in different kernel versions):
in drivers/scsi/storvsc_drv.c, storvsc_drv_init() sets
'max_outstanding_req_per_channel' to 352, and storvsc_probe() sets
'max_sub_channels' to (416 - 1) / 4 = 103 and sets scsi_driver.can_queue to
352 * (103 + 1) * (100 - 10) / 100 = 32947, which exceeds SHRT_MAX.
Use min_t(int, ...) to fix the issue.
Fixes: ea2f0f77538c ("scsi: core: Cap scsi_host cmd_per_lun at can_queue")
Cc: stable@vger.kernel.org
Signed-off-by: Dexuan Cui <decui@microsoft.com>
---
v1 tried to fix the issue by changing the storvsc driver:
https://lwn.net/ml/linux-kernel/BYAPR21MB1270BBC14D5F1AE69FC31A16BFB09@BYAPR21MB1270.namprd21.prod.outlook.com/
v2 directly fixes the scsi core change instead as Michael Kelley and
John Garry suggested (refer to the above link).
drivers/scsi/hosts.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index 3f6f14f0cafb..24b72ee4246f 100644
--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -220,7 +220,8 @@ int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev,
goto fail;
}
- shost->cmd_per_lun = min_t(short, shost->cmd_per_lun,
+ /* Use min_t(int, ...) in case shost->can_queue exceeds SHRT_MAX */
+ shost->cmd_per_lun = min_t(int, shost->cmd_per_lun,
shost->can_queue);
error = scsi_init_sense_cache(shost);
--
2.25.1
next reply other threads:[~2021-10-07 17:50 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-07 17:49 Dexuan Cui [this message]
2021-10-07 18:10 ` [PATCH v2] scsi: core: Fix shost->cmd_per_lun calculation in scsi_add_host_with_dma() Haiyang Zhang
2021-10-07 21:41 ` John Garry
2021-10-07 22:52 ` Dexuan Cui
2021-10-08 3:19 ` Ming Lei
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