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0583531bb9
iser_initialize_task_headers() uses in_interrupt() to find out if it is
safe to acquire a mutex.
in_interrupt() is deprecated as it is ill defined and does not provide
what it suggests. Aside of that it covers only parts of the contexts in
which a mutex may not be acquired.
The following callchains exist:
iscsi_queuecommand() *locks* iscsi_session::frwd_lock
-> iscsi_prep_scsi_cmd_pdu()
-> session->tt->init_task() (iscsi_iser_task_init())
-> iser_initialize_task_headers()
-> iscsi_iser_task_xmit() (iscsi_transport::xmit_task)
-> iscsi_iser_task_xmit_unsol_data()
-> iser_send_data_out()
-> iser_initialize_task_headers()
iscsi_data_xmit() *locks* iscsi_session::frwd_lock
-> iscsi_prep_mgmt_task()
-> session->tt->init_task() (iscsi_iser_task_init())
-> iser_initialize_task_headers()
-> iscsi_prep_scsi_cmd_pdu()
-> session->tt->init_task() (iscsi_iser_task_init())
-> iser_initialize_task_headers()
__iscsi_conn_send_pdu() caller has iscsi_session::frwd_lock
-> iscsi_prep_mgmt_task()
-> session->tt->init_task() (iscsi_iser_task_init())
-> iser_initialize_task_headers()
-> session->tt->xmit_task() (
The only callchain that is close to be invoked in preemptible context:
iscsi_xmitworker() worker
-> iscsi_data_xmit()
-> iscsi_xmit_task()
-> conn->session->tt->xmit_task() (iscsi_iser_task_xmit()
In iscsi_iser_task_xmit() there is this check:
if (!task->sc)
return iscsi_iser_mtask_xmit(conn, task);
so it does end up in iser_initialize_task_headers() and
iser_initialize_task_headers() relies on iscsi_task::sc == NULL.
Remove conditional locking of iser_conn::state_mutex because there is no
call chain to do so. Remove the goto label and return early now that there
is no clean up needed.
Link: https://lore.kernel.org/r/20201204174256.62xfcvudndt7oufl@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: Max Gurtovoy <maxg@nvidia.com>
Cc: Doug Ledford <dledford@redhat.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: linux-rdma@vger.kernel.org
Signed-off-by: Jason Gunthorpe <jgg@nvidia.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.