Messages in this thread | ![/](/images/icornerl.gif) | | Subject | Re: [PATCH 4.14 01/51] scsi: libsas: direct call probe and destruct | From | John Garry <> | Date | Mon, 3 Aug 2020 13:57:14 +0100 |
| |
On 03/08/2020 13:19, Greg Kroah-Hartman wrote: > From: Jason Yan <yanaijie@huawei.com> > > [ Upstream commit 0558f33c06bb910e2879e355192227a8e8f0219d ] >
Hi Greg,
This patch was one of a series from Jason to fix this WARN issue, below:
https://lore.kernel.org/linux-scsi/8f6e3763-2b04-23e8-f1ec-8ed3c58f55d3@huawei.com/
I'm doubtful that it should be taken in isolation. Maybe 1 or 2 other patches are required.
The WARN was really annoying, so we could spend a bit of time to test a backport of what is strictly required. Let us know.
Thanks, John
> 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> > Signed-off-by: Sasha Levin <sashal@kernel.org> > ---
| ![\](/images/icornerr.gif) |