Mike Marciniszyn b58fc80497 IB/hfi1: Eliminate synchronize_rcu() in mr delete ... The synchronize_rcu() call can be eliminated to improve memory deregistration performance. There are two key fields involved: - The rcu pointer itself - the lkey_published field To close the window between the rcu read of the mregion pointer and the reference count the code should: 1. To lkey/rkey validation (reader) Read the rcu pointer. If the pointer is non-NULL, get a reference. To the current validation tests use a READ_ONCE() on the lkey_published. Upon any failure release the reference. 2. To the remove logic (delete) Insure the published is zeroed prior to setting the pointer to NULL. This requires using rcu_assign_pointer() to insure lkey_published is written prior to the NULL. 3. To the insert logic (add) Insure the published is set use an rcu_assign_pointer() to insure the pointer is after all MR fields. Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com> Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com> Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com> Signed-off-by: Doug Ledford <dledford@redhat.com>		2017-04-05 14:45:09 -04:00
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rdmavt	IB/hfi1: Eliminate synchronize_rcu() in mr delete	2017-04-05 14:45:09 -04:00
rxe	This is a tree wide change and has been kept separate for that reason.	2017-02-25 13:45:43 -08:00
Makefile	Soft RoCE driver	2016-08-04 11:13:12 -04:00