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    SubjectRe: [PATCH 3.16 012/410] scsi: libsas: direct call probe and destruct
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    On 2018/6/8 2:18, Ben Hutchings wrote:
    > On Thu, 2018-06-07 at 17:32 +0100, John Garry wrote:
    >> On 07/06/2018 15:05, Ben Hutchings wrote:
    >>> 3.16.57-rc1 review patch. If anyone has any objections, please let me know.
    >>>
    >>> ------------------
    >>>
    >>
    >> Hi Ben,
    >>
    >> I noticed that you are looking to backport this patch to 3.16
    >>
    >> I am wondering why you are taking this libsas patch (and a couple other
    >> libsas patches) in isolation, when these patches were part of a series
    >> to fix libsas hotplug issues? I'm not sure if cherry-picking certain
    >> patches is ok.
    >>
    >> Maybe Jason (cc'ed) can comment further.
    >
    > This one apparently fixed a security issue (CVE-2017-18232), though I'm
    > certainly not convinced it's a particularly serious one.
    >
    > But please send objections to the list, not just privately.
    >

    Hi Ben,

    This patch is in the series below. I recommend to backport them
    together. If you really want to do this, I'm happy to help you to
    backport them.

    1689c9367bfa scsi: libsas: notify event PORTE_BROADCAST_RCVD in
    sas_enable_revalidation()
    0558f33c06bb scsi: libsas: direct call probe and destruct
    517e5153d242 scsi: libsas: use flush_workqueue to process disco events
    synchronously
    93bdbd06b164 scsi: libsas: Use new workqueue to run sas event and disco
    event
    8eea9dd84e45 scsi: libsas: make the event threshold configurable
    f12486e06ae8 scsi: libsas: shut down the PHY if events reached the threshold
    1c393b970e0f scsi: libsas: Use dynamic alloced work to avoid sas event lost

    > Ben.
    >
    >> Thanks,
    >> John
    >>
    >>> From: Jason Yan <yanaijie@huawei.com>
    >>>
    >>> commit 0558f33c06bb910e2879e355192227a8e8f0219d upstream.
    >>>
    >>> In commit 87c8331fcf72 ("[SCSI] libsas: prevent domain rediscovery
    >>> competing with ata error handling") introduced disco mutex to prevent
    >>> rediscovery competing with ata error handling and put the whole
    >>> revalidation in the mutex. But the rphy add/remove needs to wait for the
    >>> error handling which also grabs the disco mutex. This may leads to dead
    >>> lock.So the probe and destruct event were introduce to do the rphy
    >>> add/remove asynchronously and out of the lock.
    >>>
    >>> The asynchronously processed workers makes the whole discovery process
    >>> not atomic, the other events may interrupt the process. For example,
    >>> if a loss of signal event inserted before the probe event, the
    >>> sas_deform_port() is called and the port will be deleted.
    >>>
    >>> And sas_port_delete() may run before the destruct event, but the
    >>> port-x:x is the top parent of end device or expander. This leads to
    >>> a kernel WARNING such as:
    >>>
    >>> [ 82.042979] sysfs group 'power' not found for kobject 'phy-1:0:22'
    >>> [ 82.042983] ------------[ cut here ]------------
    >>> [ 82.042986] WARNING: CPU: 54 PID: 1714 at fs/sysfs/group.c:237
    >>> sysfs_remove_group+0x94/0xa0
    >>> [ 82.043059] Call trace:
    >>> [ 82.043082] [<ffff0000082e7624>] sysfs_remove_group+0x94/0xa0
    >>> [ 82.043085] [<ffff00000864e320>] dpm_sysfs_remove+0x60/0x70
    >>> [ 82.043086] [<ffff00000863ee10>] device_del+0x138/0x308
    >>> [ 82.043089] [<ffff00000869a2d0>] sas_phy_delete+0x38/0x60
    >>> [ 82.043091] [<ffff00000869a86c>] do_sas_phy_delete+0x6c/0x80
    >>> [ 82.043093] [<ffff00000863dc20>] device_for_each_child+0x58/0xa0
    >>> [ 82.043095] [<ffff000008696f80>] sas_remove_children+0x40/0x50
    >>> [ 82.043100] [<ffff00000869d1bc>] sas_destruct_devices+0x64/0xa0
    >>> [ 82.043102] [<ffff0000080e93bc>] process_one_work+0x1fc/0x4b0
    >>> [ 82.043104] [<ffff0000080e96c0>] worker_thread+0x50/0x490
    >>> [ 82.043105] [<ffff0000080f0364>] kthread+0xfc/0x128
    >>> [ 82.043107] [<ffff0000080836c0>] ret_from_fork+0x10/0x50
    >>>
    >>> Make probe and destruct a direct call in the disco and revalidate function,
    >>> but put them outside the lock. The whole discovery or revalidate won't
    >>> be interrupted by other events. And the DISCE_PROBE and DISCE_DESTRUCT
    >>> event are deleted as a result of the direct call.
    >>>
    >>> Introduce a new list to destruct the sas_port and put the port delete after
    >>> the destruct. This makes sure the right order of destroying the sysfs
    >>> kobject and fix the warning above.
    >>>
    >>> In sas_ex_revalidate_domain() have a loop to find all broadcasted
    >>> device, and sometimes we have a chance to find the same expander twice.
    >>> Because the sas_port will be deleted at the end of the whole revalidate
    >>> process, sas_port with the same name cannot be added before this.
    >>> Otherwise the sysfs will complain of creating duplicate filename. Since
    >>> the LLDD will send broadcast for every device change, we can only
    >>> process one expander's revalidation.
    >>>
    >>> [mkp: kbuild test robot warning]
    >>>
    >>> Signed-off-by: Jason Yan <yanaijie@huawei.com>
    >>> CC: John Garry <john.garry@huawei.com>
    >>> CC: Johannes Thumshirn <jthumshirn@suse.de>
    >>> CC: Ewan Milne <emilne@redhat.com>
    >>> CC: Christoph Hellwig <hch@lst.de>
    >>> CC: Tomas Henzl <thenzl@redhat.com>
    >>> CC: Dan Williams <dan.j.williams@intel.com>
    >>> Reviewed-by: Hannes Reinecke <hare@suse.com>
    >>> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
    >>> [bwh: Backported to 4.9: adjust context]
    >>> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
    >>> ---
    >>> drivers/scsi/libsas/sas_ata.c | 1 -
    >>> drivers/scsi/libsas/sas_discover.c | 32 +++++++++++++++++-------------
    >>> drivers/scsi/libsas/sas_expander.c | 8 +++-----
    >>> drivers/scsi/libsas/sas_internal.h | 1 +
    >>> drivers/scsi/libsas/sas_port.c | 3 +++
    >>> include/scsi/libsas.h | 3 +--
    >>> include/scsi/scsi_transport_sas.h | 1 +
    >>> 7 files changed, 27 insertions(+), 22 deletions(-)
    >>>
    >>> --- a/drivers/scsi/libsas/sas_ata.c
    >>> +++ b/drivers/scsi/libsas/sas_ata.c
    >>> @@ -782,7 +782,6 @@ int sas_discover_sata(struct domain_devi
    >>> if (res)
    >>> return res;
    >>>
    >>> - sas_discover_event(dev->port, DISCE_PROBE);
    >>> return 0;
    >>> }
    >>>
    >>> --- a/drivers/scsi/libsas/sas_discover.c
    >>> +++ b/drivers/scsi/libsas/sas_discover.c
    >>> @@ -212,13 +212,9 @@ void sas_notify_lldd_dev_gone(struct dom
    >>> }
    >>> }
    >>>
    >>> -static void sas_probe_devices(struct work_struct *work)
    >>> +static void sas_probe_devices(struct asd_sas_port *port)
    >>> {
    >>> struct domain_device *dev, *n;
    >>> - struct sas_discovery_event *ev = to_sas_discovery_event(work);
    >>> - struct asd_sas_port *port = ev->port;
    >>> -
    >>> - clear_bit(DISCE_PROBE, &port->disc.pending);
    >>>
    >>> /* devices must be domain members before link recovery and probe */
    >>> list_for_each_entry(dev, &port->disco_list, disco_list_node) {
    >>> @@ -294,7 +290,6 @@ int sas_discover_end_dev(struct domain_d
    >>> res = sas_notify_lldd_dev_found(dev);
    >>> if (res)
    >>> return res;
    >>> - sas_discover_event(dev->port, DISCE_PROBE);
    >>>
    >>> return 0;
    >>> }
    >>> @@ -353,13 +348,9 @@ static void sas_unregister_common_dev(st
    >>> sas_put_device(dev);
    >>> }
    >>>
    >>> -static void sas_destruct_devices(struct work_struct *work)
    >>> +void sas_destruct_devices(struct asd_sas_port *port)
    >>> {
    >>> struct domain_device *dev, *n;
    >>> - struct sas_discovery_event *ev = to_sas_discovery_event(work);
    >>> - struct asd_sas_port *port = ev->port;
    >>> -
    >>> - clear_bit(DISCE_DESTRUCT, &port->disc.pending);
    >>>
    >>> list_for_each_entry_safe(dev, n, &port->destroy_list, disco_list_node) {
    >>> list_del_init(&dev->disco_list_node);
    >>> @@ -370,6 +361,16 @@ static void sas_destruct_devices(struct
    >>> }
    >>> }
    >>>
    >>> +static void sas_destruct_ports(struct asd_sas_port *port)
    >>> +{
    >>> + struct sas_port *sas_port, *p;
    >>> +
    >>> + list_for_each_entry_safe(sas_port, p, &port->sas_port_del_list, del_list) {
    >>> + list_del_init(&sas_port->del_list);
    >>> + sas_port_delete(sas_port);
    >>> + }
    >>> +}
    >>> +
    >>> void sas_unregister_dev(struct asd_sas_port *port, struct domain_device *dev)
    >>> {
    >>> if (!test_bit(SAS_DEV_DESTROY, &dev->state) &&
    >>> @@ -384,7 +385,6 @@ void sas_unregister_dev(struct asd_sas_p
    >>> if (!test_and_set_bit(SAS_DEV_DESTROY, &dev->state)) {
    >>> sas_rphy_unlink(dev->rphy);
    >>> list_move_tail(&dev->disco_list_node, &port->destroy_list);
    >>> - sas_discover_event(dev->port, DISCE_DESTRUCT);
    >>> }
    >>> }
    >>>
    >>> @@ -490,6 +490,8 @@ static void sas_discover_domain(struct w
    >>> port->port_dev = NULL;
    >>> }
    >>>
    >>> + sas_probe_devices(port);
    >>> +
    >>> SAS_DPRINTK("DONE DISCOVERY on port %d, pid:%d, result:%d\n", port->id,
    >>> task_pid_nr(current), error);
    >>> }
    >>> @@ -523,6 +525,10 @@ static void sas_revalidate_domain(struct
    >>> port->id, task_pid_nr(current), res);
    >>> out:
    >>> mutex_unlock(&ha->disco_mutex);
    >>> +
    >>> + sas_destruct_devices(port);
    >>> + sas_destruct_ports(port);
    >>> + sas_probe_devices(port);
    >>> }
    >>>
    >>> /* ---------- Events ---------- */
    >>> @@ -578,10 +584,8 @@ void sas_init_disc(struct sas_discovery
    >>> static const work_func_t sas_event_fns[DISC_NUM_EVENTS] = {
    >>> [DISCE_DISCOVER_DOMAIN] = sas_discover_domain,
    >>> [DISCE_REVALIDATE_DOMAIN] = sas_revalidate_domain,
    >>> - [DISCE_PROBE] = sas_probe_devices,
    >>> [DISCE_SUSPEND] = sas_suspend_devices,
    >>> [DISCE_RESUME] = sas_resume_devices,
    >>> - [DISCE_DESTRUCT] = sas_destruct_devices,
    >>> };
    >>>
    >>> disc->pending = 0;
    >>> --- a/drivers/scsi/libsas/sas_expander.c
    >>> +++ b/drivers/scsi/libsas/sas_expander.c
    >>> @@ -1903,7 +1903,8 @@ static void sas_unregister_devs_sas_addr
    >>> sas_port_delete_phy(phy->port, phy->phy);
    >>> sas_device_set_phy(found, phy->port);
    >>> if (phy->port->num_phys == 0)
    >>> - sas_port_delete(phy->port);
    >>> + list_add_tail(&phy->port->del_list,
    >>> + &parent->port->sas_port_del_list);
    >>> phy->port = NULL;
    >>> }
    >>> }
    >>> @@ -2111,7 +2112,7 @@ int sas_ex_revalidate_domain(struct doma
    >>> struct domain_device *dev = NULL;
    >>>
    >>> res = sas_find_bcast_dev(port_dev, &dev);
    >>> - while (res == 0 && dev) {
    >>> + if (res == 0 && dev) {
    >>> struct expander_device *ex = &dev->ex_dev;
    >>> int i = 0, phy_id;
    >>>
    >>> @@ -2123,9 +2124,6 @@ int sas_ex_revalidate_domain(struct doma
    >>> res = sas_rediscover(dev, phy_id);
    >>> i = phy_id + 1;
    >>> } while (i < ex->num_phys);
    >>> -
    >>> - dev = NULL;
    >>> - res = sas_find_bcast_dev(port_dev, &dev);
    >>> }
    >>> return res;
    >>> }
    >>> --- a/drivers/scsi/libsas/sas_internal.h
    >>> +++ b/drivers/scsi/libsas/sas_internal.h
    >>> @@ -100,6 +100,7 @@ int sas_try_ata_reset(struct asd_sas_phy
    >>> void sas_hae_reset(struct work_struct *work);
    >>>
    >>> void sas_free_device(struct kref *kref);
    >>> +void sas_destruct_devices(struct asd_sas_port *port);
    >>>
    >>> #ifdef CONFIG_SCSI_SAS_HOST_SMP
    >>> extern int sas_smp_host_handler(struct Scsi_Host *shost, struct request *req,
    >>> --- a/drivers/scsi/libsas/sas_port.c
    >>> +++ b/drivers/scsi/libsas/sas_port.c
    >>> @@ -66,6 +66,7 @@ static void sas_resume_port(struct asd_s
    >>> rc = sas_notify_lldd_dev_found(dev);
    >>> if (rc) {
    >>> sas_unregister_dev(port, dev);
    >>> + sas_destruct_devices(port);
    >>> continue;
    >>> }
    >>>
    >>> @@ -219,6 +220,7 @@ void sas_deform_port(struct asd_sas_phy
    >>>
    >>> if (port->num_phys == 1) {
    >>> sas_unregister_domain_devices(port, gone);
    >>> + sas_destruct_devices(port);
    >>> sas_port_delete(port->port);
    >>> port->port = NULL;
    >>> } else {
    >>> @@ -323,6 +325,7 @@ static void sas_init_port(struct asd_sas
    >>> INIT_LIST_HEAD(&port->dev_list);
    >>> INIT_LIST_HEAD(&port->disco_list);
    >>> INIT_LIST_HEAD(&port->destroy_list);
    >>> + INIT_LIST_HEAD(&port->sas_port_del_list);
    >>> spin_lock_init(&port->phy_list_lock);
    >>> INIT_LIST_HEAD(&port->phy_list);
    >>> port->ha = sas_ha;
    >>> --- a/include/scsi/libsas.h
    >>> +++ b/include/scsi/libsas.h
    >>> @@ -87,10 +87,8 @@ enum discover_event {
    >>> DISCE_DISCOVER_DOMAIN = 0U,
    >>> DISCE_REVALIDATE_DOMAIN,
    >>> DISCE_PORT_GONE,
    >>> - DISCE_PROBE,
    >>> DISCE_SUSPEND,
    >>> DISCE_RESUME,
    >>> - DISCE_DESTRUCT,
    >>> DISC_NUM_EVENTS,
    >>> };
    >>>
    >>> @@ -274,6 +272,7 @@ struct asd_sas_port {
    >>> struct list_head dev_list;
    >>> struct list_head disco_list;
    >>> struct list_head destroy_list;
    >>> + struct list_head sas_port_del_list;
    >>> enum sas_linkrate linkrate;
    >>>
    >>> struct sas_work work;
    >>> --- a/include/scsi/scsi_transport_sas.h
    >>> +++ b/include/scsi/scsi_transport_sas.h
    >>> @@ -145,6 +145,7 @@ struct sas_port {
    >>>
    >>> struct mutex phy_list_mutex;
    >>> struct list_head phy_list;
    >>> + struct list_head del_list; /* libsas only */
    >>> };
    >>>
    >>> #define dev_to_sas_port(d) \
    >>>
    >>>
    >>> .
    >>>
    >>
    >>

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