On 29/11/2019 03:24, yanaijie wrote:
The discovering of sas port is driving by workqueue in libsas. When
libsas is processing port events or phy events in workqueue, new evnets
/s/evnets/events/
may rise up and change the state of some structures such as asd_sas_phy.
This may cause some problems such as follows:
==>thread 1 ==>thread 2
==>phy up
==>phy_up_v3_hw()
==>oob_mode = SATA_OOB_MODE;
==>phy donw quickly
down
==>hisi_sas_phy_down()
==>sas_ha->notify_phy_event()
==>sas_phy_disconnected()
==>oob_mode = OOB_NOT_CONNECTED
==>workqueue wakeup
==>sas_form_port()
==>sas_discover_domain()
==>sas_get_port_device()
==>oob_mode is OOB_NOT_CONNECTED and device
is wrongly taken as expander
This at last lead to the panic when libsas trying to issue a command to
discover the device.
[183047.614035] Unable to handle kernel NULL pointer dereference at
virtual address 0000000000000058
[183047.622896] Mem abort info:
[183047.625762] ESR = 0x96000004
[183047.628893] Exception class = DABT (current EL), IL = 32 bits
[183047.634888] SET = 0, FnV = 0
[183047.638015] EA = 0, S1PTW = 0
[183047.641232] Data abort info:
[183047.644189] ISV = 0, ISS = 0x00000004
[183047.648100] CM = 0, WnR = 0
[183047.651145] user pgtable: 4k pages, 48-bit VAs, pgdp =
00000000b7df67be
[183047.657834] [0000000000000058] pgd=0000000000000000
[183047.662789] Internal error: Oops: 96000004 [#1] SMP
[183047.667740] Process kworker/u16:2 (pid: 31291, stack limit =
0x00000000417c4974)
[183047.675208] CPU: 0 PID: 3291 Comm: kworker/u16:2 Tainted: G
W OE 4.19.36-vhulk1907.1.0.h410.eulerosv2r8.aarch64 #1
[183047.687015] Hardware name: N/A N/A/Kunpeng Desktop Board D920S10,
BIOS 0.15 10/22/2019
[183047.695007] Workqueue: 0000:74:02.0_disco_q sas_discover_domain
[183047.700999] pstate: 20c00009 (nzCv daif +PAN +UAO)
[183047.705864] pc : prep_ata_v3_hw+0xf8/0x230 [hisi_sas_v3_hw]
Can you explain how we discover an expander device yet try to send an
ATA command?
[183047.711510] lr : prep_ata_v3_hw+0xb0/0x230 [hisi_sas_v3_hw]
[183047.717153] sp : ffff00000f28ba60
[183047.720541] x29: ffff00000f28ba60 x28: ffff8026852d7228
[183047.725925] x27: ffff8027dba3e0a8 x26: ffff8027c05fc200
[183047.731310] x25: 0000000000000000 x24: ffff8026bafa8dc0
[183047.736695] x23: ffff8027c05fc218 x22: ffff8026852d7228
[183047.742079] x21: ffff80007c2f2940 x20: ffff8027c05fc200
[183047.747464] x19: 0000000000f80800 x18: 0000000000000010
[183047.752848] x17: 0000000000000000 x16: 0000000000000000
[183047.758232] x15: ffff000089a5a4ff x14: 0000000000000005
[183047.763617] x13: ffff000009a5a50e x12: ffff8026bafa1e20
[183047.769001] x11: ffff0000087453b8 x10: ffff00000f28b870
[183047.774385] x9 : 0000000000000000 x8 : ffff80007e58f9b0
[183047.779770] x7 : 0000000000000000 x6 : 000000000000003f
[183047.785154] x5 : 0000000000000040 x4 : ffffffffffffffe0
[183047.790538] x3 : 00000000000000f8 x2 : 0000000002000007
[183047.795922] x1 : 0000000000000008 x0 : 0000000000000000
[183047.801307] Call trace:
[183047.803827] prep_ata_v3_hw+0xf8/0x230 [hisi_sas_v3_hw]
[183047.809127] hisi_sas_task_prep+0x750/0x888 [hisi_sas_main]
[183047.814773] hisi_sas_task_exec.isra.7+0x88/0x1f0 [hisi_sas_main]
[183047.820939] hisi_sas_queue_command+0x28/0x38 [hisi_sas_main]
[183047.826757] smp_execute_task_sg+0xec/0x218
[183047.831013] smp_execute_task+0x74/0xa0
[183047.834921] sas_discover_expander.part.7+0x9c/0x5f8
[183047.839959] sas_discover_root_expander+0x90/0x160
[183047.844822] sas_discover_domain+0x1b8/0x1e8
[183047.849164] process_one_work+0x1b4/0x3f8
[183047.853246] worker_thread+0x54/0x470
[183047.856981] kthread+0x134/0x138
[183047.860283] ret_from_fork+0x10/0x18
[183047.863931] Code: f9407a80 528000e2 39409281 72a04002 (b9405800)
[183047.870097] kernel fault(0x1) notification starting on CPU 0
[183047.875828] kernel fault(0x1) notification finished on CPU 0
[183047.881559] Modules linked in: unibsp(OE) hns3(OE) hclge(OE)
hnae3(OE) mem_drv(OE) hisi_sas_v3_hw(OE) hisi_sas_main(OE)
[183047.892418] ---[ end trace 4cc26083fc11b783 ]---
[183047.897107] Kernel panic - not syncing: Fatal exception
[183047.902403] kernel fault(0x5) notification starting on CPU 0
[183047.908134] kernel fault(0x5) notification finished on CPU 0
[183047.913865] SMP: stopping secondary CPUs
[183047.917861] Kernel Offset: disabled
[183047.921422] CPU features: 0x2,a2a00a38
[183047.925243] Memory Limit: none
[183047.928372] kernel reboot(0x2) notification starting on CPU 0
[183047.934190] kernel reboot(0x2) notification finished on CPU 0
[183047.940008] ---[ end Kernel panic - not syncing: Fatal exception
]---
Fixes: 2908d778ab3e ("[SCSI] aic94xx: new driver")
I am not sure if it is appropriate to identify this as what we're
fixing, since we changed significantly the event processing in libsas
since 2908d778ab3e?
Reported-by: Gao Chuan <gaochuan4@xxxxxxxxxx>
Signed-off-by: Jason Yan <yanaijie@xxxxxxxxxx>
---
drivers/scsi/libsas/sas_discover.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/scsi/libsas/sas_discover.c b/drivers/scsi/libsas/sas_discover.c
index f47b4b281b14..23fdbc8fa05a 100644
--- a/drivers/scsi/libsas/sas_discover.c
+++ b/drivers/scsi/libsas/sas_discover.c
@@ -81,12 +81,18 @@ static int sas_get_port_device(struct asd_sas_port *port)
else
dev->dev_type = SAS_SATA_DEV;
dev->tproto = SAS_PROTOCOL_SATA;
- } else {
+ } else if (port->oob_mode == SAS_OOB_MODE) {
This just looks racy. We're sending an event and then checking some
volatile shared memory in the event processing :(
struct sas_identify_frame *id =
(struct sas_identify_frame *) dev->frame_rcvd;
dev->dev_type = id->dev_type;
dev->iproto = id->initiator_bits;
dev->tproto = id->target_bits;
+ } else {
+ /* If the oob mode is OOB_NOT_CONNECTED, the port is
+ * disconnected due to race with PHY down. We cannot
+ * continue to discover this port */
+ sas_put_device(dev);
+ return rc;
}
sas_init_dev(dev);
