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From:   Xingui Yang <yangxingui@huawei.com>
To:     <john.g.garry@oracle.com>, <yanaijie@huawei.com>,
        <jejb@linux.ibm.com>, <martin.petersen@oracle.com>
CC:     <linux-scsi@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <linuxarm@huawei.com>, <yangxingui@huawei.com>,
        <prime.zeng@hisilicon.com>, <kangfenglong@huawei.com>,
        <xiabing12@h-partners.com>
Subject: [PATCH] scsi: libsas: fix set zero-address when device-type != NO_DEVICE
Date:   Fri, 20 Oct 2023 02:42:40 +0000
Message-ID: <20231020024240.7708-1-yangxingui@huawei.com>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

phy->attached_sas_addr will be set to a zero-address when
phy->linkrate < SAS_LINK_RATE_1_5_GBPS but device-type != NO_DEVICE,
and it may trigger BUG() as follows when do revalidate with zero-address:

[562240.062536] sas: ex 500e004aaaaaaa1f phy0 new device attached
[562240.062616] sas: ex 500e004aaaaaaa1f phy00:U:5 attached: 0000000000000000 (stp)
[562240.062680]  port-7:7:0: trying to add phy phy-7:7:19 fails: it's already part of another port
[562240.085064] ------------[ cut here ]------------
[562240.096612] kernel BUG at drivers/scsi/scsi_transport_sas.c:1083!
[562240.109611] Internal error: Oops - BUG: 0 [#1] SMP
[562240.343518] Process kworker/u256:3 (pid: 435909, stack limit = 0x0000000003bcbebf)
[562240.421714] Workqueue: 0000:b4:02.0_disco_q sas_revalidate_domain [libsas]
[562240.437173] pstate: 40c00009 (nZcv daif +PAN +UAO)
[562240.450478] pc : sas_port_add_phy+0x13c/0x168 [scsi_transport_sas]
[562240.465283] lr : sas_port_add_phy+0x13c/0x168 [scsi_transport_sas]
[562240.479751] sp : ffff0000300cfa70
[562240.674822] Call trace:
[562240.682709]  sas_port_add_phy+0x13c/0x168 [scsi_transport_sas]
[562240.694013]  sas_ex_get_linkrate.isra.5+0xcc/0x128 [libsas]
[562240.704957]  sas_ex_discover_end_dev+0xfc/0x538 [libsas]
[562240.715508]  sas_ex_discover_dev+0x3cc/0x4b8 [libsas]
[562240.725634]  sas_ex_discover_devices+0x9c/0x1a8 [libsas]
[562240.735855]  sas_ex_revalidate_domain+0x2f0/0x450 [libsas]
[562240.746123]  sas_revalidate_domain+0x158/0x160 [libsas]
[562240.756014]  process_one_work+0x1b4/0x448
[562240.764548]  worker_thread+0x54/0x468
[562240.772562]  kthread+0x134/0x138
[562240.779989]  ret_from_fork+0x10/0x18

So set a zero-address for phy->attached_sas_addr only when
phy->attached_dev_type == NO_DEVICE.

Fixes: 7d1d86518118 ("[SCSI] libsas: fix false positive 'device attached' conditions")

Signed-off-by: Xingui Yang <yangxingui@huawei.com>
---
 drivers/scsi/libsas/sas_expander.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c
index a2204674b680..5a81754d3768 100644
--- a/drivers/scsi/libsas/sas_expander.c
+++ b/drivers/scsi/libsas/sas_expander.c
@@ -239,8 +239,7 @@ static void sas_set_ex_phy(struct domain_device *dev, int phy_id,
 	/* help some expanders that fail to zero sas_address in the 'no
 	 * device' case
 	 */
-	if (phy->attached_dev_type == SAS_PHY_UNUSED ||
-	    phy->linkrate < SAS_LINK_RATE_1_5_GBPS)
+	if (phy->attached_dev_type == SAS_PHY_UNUSED)
 		memset(phy->attached_sas_addr, 0, SAS_ADDR_SIZE);
 	else
 		memcpy(phy->attached_sas_addr, dr->attached_sas_addr, SAS_ADDR_SIZE);
-- 
2.17.1