Messages in this thread | | | Date | Fri, 24 Nov 2023 10:27:53 +0800 | Subject | Re: [PATCH v4] scsi: libsas: Fix the failure of adding phy with zero-address to port | From | yangxingui <> |
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Hi John,
On 2023/11/23 22:52, John Garry wrote: > On 17/11/2023 09:00, Xingui Yang wrote: > > Sorry for being slow to come back to this. However I still have > questions... > >> When connecting to the epander device, first disable and then enable the > > /s/epander/expander/ > > And connecting what to the expander? Is it a SATA disk? > > Or the SATA disk is already attached to the expander and we are now > attaching the expander to the host? > > It is hard to follow this. > >> local phy. > > So is the local phy disabled initially? Or is was it initially enabled > and we disable+re-enable just when attaching, so that there is a race? > >> The following BUG() will be triggered with a small probability: >> >> [562240.051046] sas: phy19 part of wide port with phy16 > > Where is this print in the code? I see "part of a wide port with > phy%02d" in sas_discover_dev() > >> [562240.051197] sas: ex 500e004aaaaaaa1f phy19:U:0 attached: >> 0000000000000000 (no device) >> [562240.051203] sas: done REVALIDATING DOMAIN on port 0, pid:435909, >> res 0x0 >> <...> >> [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 >> >> What causes this problem: >> 1. When phy19 was initially added to the parent port, ex_phy->port was >> not > > phy19 is the expander phy attached to the host, right? > >> set. As a result, when phy19 was removed from the parent wide port, > > You seem to be getting ahead of yourself. It has not been mentioned when > phy19 is removed from the parent wide port. > >> it was >> not deleted from the phy_list of the parent port. >> >> 2. The rate of the newly connected SATA device to phy0 is less than 1.5G, >> and its sas_address was set to 0. After creating port 7:7:0 > > is 7:7:0 the port which the SATA device is part of? > >> , it attempts to >> add the expander's other zero-addressed phy to this port. >> >> 3. When adding phy19 to port-7:7:0 > > Which would be the incorrect thing to do, right? I am basing that on my > assumption that 7:7:0 is the port which the SATA device is part of. > >> , it is prompted that phy19 already >> belongs to another port, which triggers the current problem. >> >> Fix the problem as follows: >> 1. When ex_phy is added to the parent port, set ex_phy->port to >> ex_dev->parent_port. >> >> 2. Set ex_dev->parent_port to NULL when the parent port's PHY count is 0. >> >> 3. When phy->attached_dev_type != NO_DEVICE, do not set the zero address >> for phy->attached_sas_addr. >> >> Fixes: 2908d778ab3e ("[SCSI] aic94xx: new driver") >> Fixes: 7d1d86518118 ("[SCSI] libsas: fix false positive 'device >> attached' conditions") >> Signed-off-by: Xingui Yang <yangxingui@huawei.com> >> --- >> v3 -> v4: >> 1. Update patch title and comments based on John's suggestion. >> >> v2 -> v3: >> 1. Set ex_dev->parent_port to NULL when the number of PHYs of the parent >> port becomes 0 >> 2. Update the comments >> >> v1 -> v2: >> 1. Set ex_phy->port with parent_port when ex_phy is added to the >> parent port >> 2. Set ex_phy to NULL when free expander >> 3. Update the comments >> --- >> drivers/scsi/libsas/sas_discover.c | 4 +++- >> drivers/scsi/libsas/sas_expander.c | 8 +++++--- >> drivers/scsi/libsas/sas_internal.h | 1 + >> 3 files changed, 9 insertions(+), 4 deletions(-) >> >> diff --git a/drivers/scsi/libsas/sas_discover.c >> b/drivers/scsi/libsas/sas_discover.c >> index 8fb7c41c0962..8eb3888a9e57 100644 >> --- a/drivers/scsi/libsas/sas_discover.c >> +++ b/drivers/scsi/libsas/sas_discover.c >> @@ -296,8 +296,10 @@ void sas_free_device(struct kref *kref) >> dev->phy = NULL; >> /* remove the phys and ports, everything else should be gone */ >> - if (dev_is_expander(dev->dev_type)) >> + if (dev_is_expander(dev->dev_type)) { >> kfree(dev->ex_dev.ex_phy); >> + dev->ex_dev.ex_phy = NULL; > > This is strange, as we free the dev later. Where can dev->ex_dev.ex_phy > be checked before dev is freed? Yes, I saw this when locating this problem and detecting resource release. Usually after calling kfree, we will set the pointer to null. It has little to do with the current problem. I can delete this part of the modification.
> >> + } >> if (dev_is_sata(dev) && dev->sata_dev.ap) { >> ata_sas_tport_delete(dev->sata_dev.ap); >> diff --git a/drivers/scsi/libsas/sas_expander.c >> b/drivers/scsi/libsas/sas_expander.c >> index a2204674b680..89d44a9dc4e3 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); >> @@ -1844,9 +1843,12 @@ static void sas_unregister_devs_sas_addr(struct >> domain_device *parent, >> if (phy->port) { >> sas_port_delete_phy(phy->port, phy->phy); >> sas_device_set_phy(found, phy->port); >> - if (phy->port->num_phys == 0) >> + if (phy->port->num_phys == 0) { >> list_add_tail(&phy->port->del_list, >> &parent->port->sas_port_del_list); >> + if (ex_dev->parent_port == phy->port) >> + ex_dev->parent_port = NULL; >> + } >> phy->port = NULL; >> } >> } >> diff --git a/drivers/scsi/libsas/sas_internal.h >> b/drivers/scsi/libsas/sas_internal.h >> index 3804aef165ad..e860d5b19880 100644 >> --- a/drivers/scsi/libsas/sas_internal.h >> +++ b/drivers/scsi/libsas/sas_internal.h >> @@ -202,6 +202,7 @@ static inline void sas_add_parent_port(struct >> domain_device *dev, int phy_id) >> sas_port_mark_backlink(ex->parent_port); >> } >> sas_port_add_phy(ex->parent_port, ex_phy->phy); >> + ex_phy->port = ex->parent_port; > > We already do this in sas_ex_join_wide_port(), right? No, If the addr of ex_phy matches dev->parent, sas_ex_join_wide_port() will not be called, but sas_add_parent_port() will be called as follows: static int sas_ex_discover_dev(struct domain_device *dev, int phy_id) { struct expander_device *ex = &dev->ex_dev; struct ex_phy *ex_phy = &ex->ex_phy[phy_id]; struct domain_device *child = NULL; int res = 0;
<...> /* Parent and domain coherency */ if (!dev->parent && sas_phy_match_port_addr(dev->port, ex_phy)) { sas_add_parent_port(dev, phy_id); return 0; } if (dev->parent && sas_phy_match_dev_addr(dev->parent, ex_phy)) { sas_add_parent_port(dev, phy_id); if (ex_phy->routing_attr == TABLE_ROUTING) sas_configure_phy(dev, phy_id, dev->port->sas_addr, 1); return 0; } <...> }
> > I am not saying that what we do now does not have a problem - I am just > trying to understand what currently happens
ok, because ex_phy->port is not set when calling sas_add_parent_port(), when deleting phy from the parent wide port, it is not removed from the phy_list of the parent wide port as follows: static void sas_unregister_devs_sas_addr(struct domain_device *parent, int phy_id, bool last) { <...> // Since ex_phy->port is not set, this branch will not be enter if (phy->port) { sas_port_delete_phy(phy->port, phy->phy); sas_device_set_phy(found, phy->port); if (phy->port->num_phys == 0) { list_add_tail(&phy->port->del_list, &parent->port->sas_port_del_list); if (ex_dev->parent_port == phy->port) ex_dev->parent_port = NULL; } phy->port = NULL; } }
Thanks, Xingui .
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