>>>>> "Chris" == Chris Leech <cleech@xxxxxxxxxx> writes: Chris> There's a rather long standing regression from commit 659743b Chris> [SCSI] libiscsi: Reduce locking contention in fast path Chris> Depending on iSCSI target behavior, it's possible to hit the case Chris> in iscsi_complete_task where the task is still on a pending list Chris> (!list_empty(&task->running)). When that happens the task is Chris> removed from the list while holding the session back_lock, but Chris> other task list modification occur under the frwd_lock. That Chris> leads to linked list corruption and eventually a panicked system. Chris> Rather than back out the session lock split entirely, in order to Chris> try and keep some of the performance gains this patch adds Chris> another lock to maintain the task lists integrity. Chris> Major enterprise supported kernels have been backing out the lock Chris> split for while now, thanks to the efforts at IBM where a lab Chris> setup has the most reliable reproducer I've seen on this issue. Chris> This patch has been tested there successfully. Reviews, please! -- Martin K. Petersen Oracle Linux Engineering
