scsi: iscsi: Add support for asynchronous iSCSI session destruction

iSCSI session destruction can be arbitrarily slow, since it might require
network operations and serialization inside the SCSI layer.  This patch
adds a new user event to trigger the destruction work asynchronously,
releasing the rx_queue_mutex as soon as the operation is queued and before
it is performed.  This change allows other operations to run in other
sessions in the meantime, removing one of the major iSCSI bottlenecks for
us.

To prevent the session from being used after the destruction request, we
remove it immediately from the sesslist. This simplifies the locking
required during the asynchronous removal.

Link: https://lore.kernel.org/r/[email protected]
Co-developed-by: Gabriel Krisman Bertazi <[email protected]>
Co-developed-by: Khazhismel Kumykov <[email protected]>
Reviewed-by: Lee Duncan <[email protected]>
Signed-off-by: Gabriel Krisman Bertazi <[email protected]>
Signed-off-by: Frank Mayhar <[email protected]>
Signed-off-by: Khazhismel Kumykov <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

0 files changed, 0 insertions, 0 deletions