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When device gone, it will check whether it is during reset, if not, it will
send internal task abort. Before internal task abort returned, reset
begins, and it will check whether SAS_PHY_UNUSED is set, if not, it will
call hisi_sas_init_device(), but at that time domain_device may already be
freed or part of it is freed, so it may referenece null pointer in
hisi_sas_init_device(). It may occur as follows:
thread0 thread1
hisi_sas_dev_gone()
check whether in RESET(no)
internal task abort
reset prep
soft_reset
... (part of reset_done)
internal task abort failed
release resource anyway
clear_itct
device->lldd_dev=NULL
hisi_sas_reset_init_all_device
check sas_dev->dev_type is SAS_PHY_UNUSED and
!device
set dev_type SAS_PHY_UNUSED
sas_free_device
hisi_sas_init_device
...
Semaphore hisi_hba.sema is used to sync the processes of device gone and
host reset.
To solve the issue, expand the scope that semaphore protects and let them
never occur together.
And also some places will check whether domain_device is NULL to judge
whether the device is gone. So when device gone, need to clear
sas_dev->sas_device.
Link: https://lore.kernel.org/r/1567774537-20003-14-git-send-email-john.garry@huawei.com
Signed-off-by: Xiang Chen <chenxiang66@hisilicon.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.