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In the lldd api, a lldd may unregister a remoteport (loss of connectivity or driver unload) or localport (driver unload). The lldd must wait for the remoteport_delete or localport_delete before completing its actions post the unregister. The xxx_deletes currently occur only when the xxxport structure is fully freed after all references are removed. Thus the lldd may be held hostage until an app or in-kernel entity that has a namespace open finally closes so the namespace can be removed, the controller removed, thus the transport objects, thus the lldd. This patch decouples the transport and os-facing objects from the lldd and the remoteport and localport. There is a point in all deletions where the transport will no longer interact with the lldd on behalf of a controller. That point centers around the association established with the target/subsystem. It will access the lldd whenever it attempts to create an association and while the association is active. New associations may only be created if the remoteport is live (thus the localport is live). It will not access the lldd after deleting the association. Therefore, the patch tracks the count of active controllers - those with associations being created or that are active - on a remoteport. It also tracks the number of remoteports that have active controllers, on a a localport. When a remoteport is unregistered, as soon as there are no active controllers, the lldd's remoteport_delete may be called and the lldd may continue. Similarly, when a localport is unregistered, as soon as there are no remoteports with active controllers, the localport_delete callback may be made. This significantly speeds up unregistration with the lldd. The transport objects continue in suspended status with reconnect timers running, and upon expiration, normal ref-counting will occur and the objects will be freed. The transport object may still be held hostage by the application/kernel module, but that is acceptable. With this change, the lldd may be fully unloaded and reloaded, and if registrations occur prior to the timeouts, the nvme controller and namespaces will resume normally as if a link bounce. Signed-off-by: James Smart <james.smart@broadcom.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk> |
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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.