Re: [PATCH net-next v2 3/7] ibmvnic: avoid allocating rwi entries

On Tue, 2021-01-12 at 10:14 -0800, Sukadev Bhattiprolu wrote:

Whenever we need to schedule a reset, we allocate an rwi (reset work
item?) entry and add to the list of pending resets.

Since we only add one rwi for a given reason type to the list (no
duplicates).
we will only have a handful of reset types in the list - even in the
worst case. In the common case we should just have a couple of
entries
at most.

Rather than allocating/freeing every time (and dealing with the
corner
case of the allocation failing), use a fixed number of rwi entries.
The extra memory needed is tiny and most of it will be used over the
active life of the adapter.

This also fixes a couple of tiny memory leaks. One is in
ibmvnic_reset()
where we don't free the rwi entries after deleting them from the list
due
to a transport event.  The second is in __ibmvnic_reset() where if we
find that the adapter is being removed, we simply break out of the
loop
(with rc = EBUSY) but ignore any rwi entries that remain on the list.

Fixes: 2770a7984db58 ("Introduce hard reset recovery")
Fixes: 36f1031c51a2 ("ibmvnic: Do not process reset during or after
device removal")
Signed-off-by: Sukadev Bhattiprolu <redacted>
---
 drivers/net/ethernet/ibm/ibmvnic.c | 123 +++++++++++++++++--------
----
 drivers/net/ethernet/ibm/ibmvnic.h |  14 ++--
 2 files changed, 78 insertions(+), 59 deletions(-)

[...]

-enum ibmvnic_reset_reason {VNIC_RESET_FAILOVER = 1,
+enum ibmvnic_reset_reason {VNIC_RESET_UNUSED = 0,
+			   VNIC_RESET_FAILOVER = 1,
 			   VNIC_RESET_MOBILITY,
 			   VNIC_RESET_FATAL,
 			   VNIC_RESET_NON_FATAL,
 			   VNIC_RESET_TIMEOUT,
-			   VNIC_RESET_CHANGE_PARAM};
-
-struct ibmvnic_rwi {
-	enum ibmvnic_reset_reason reset_reason;
-	struct list_head list;
-};
+			   VNIC_RESET_CHANGE_PARAM,
+			   VNIC_RESET_MAX};	// must be last

       this is not the preferred comment style: ^^

I would just drop the comment here, it is clear from the name of the
enum.