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If tcmu-runner is processing a STPG and needs to change the kernel's ALUA state then we cannot use the same work queue for task management requests and ALUA transitions, because we could deadlock. The problem occurs when a STPG times out before tcmu-runner is able to call into target_tg_pt_gp_alua_access_state_store-> core_alua_do_port_transition -> core_alua_do_transition_tg_pt -> queue_work. In this case, the tmr is on the work queue waiting for the STPG to complete, but the STPG transition is now queued behind the waiting tmr. Note: This bug will also be fixed by this patch: http://www.spinics.net/lists/target-devel/msg14560.html which switches the tmr code to use the system workqueues. For both, I am not sure if we need a dedicated workqueue since it is not a performance path and I do not think we need WQ_MEM_RECLAIM to make forward progress to free up memory like the block layer does. Signed-off-by: Mike Christie <mchristi@redhat.com> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.