IB/srp: allow lockless work posting
Only one CPU at a time will own an RX IU, so using the address of the IU
as the work request cookie allows us to avoid taking a lock. We can
similarly prepare the TX path for lockless posting by moving the free TX
IUs to a list. This also removes the requirement that the queue sizes be
a power of 2.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
[ broken out, small cleanups, and modified to avoid needing an extra field
in the IU by David Dillow]
Signed-off-by: David Dillow <dillowda@ornl.gov>
diff --git a/drivers/infiniband/ulp/srp/ib_srp.h b/drivers/infiniband/ulp/srp/ib_srp.h
index f8b689a..41ecb46 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.h
+++ b/drivers/infiniband/ulp/srp/ib_srp.h
@@ -59,10 +59,8 @@
SRP_RQ_SHIFT = 6,
SRP_RQ_SIZE = 1 << SRP_RQ_SHIFT,
- SRP_RQ_MASK = SRP_RQ_SIZE - 1,
SRP_SQ_SIZE = SRP_RQ_SIZE,
- SRP_SQ_MASK = SRP_SQ_SIZE - 1,
SRP_RSP_SQ_SIZE = 1,
SRP_REQ_SQ_SIZE = SRP_SQ_SIZE - SRP_RSP_SQ_SIZE,
SRP_TSK_MGMT_SQ_SIZE = 1,
@@ -144,11 +142,9 @@
int zero_req_lim;
- unsigned rx_head;
struct srp_iu *rx_ring[SRP_RQ_SIZE];
- unsigned tx_head;
- unsigned tx_tail;
+ struct list_head free_tx;
struct srp_iu *tx_ring[SRP_SQ_SIZE];
struct list_head free_reqs;
@@ -168,6 +164,7 @@
};
struct srp_iu {
+ struct list_head list;
u64 dma;
void *buf;
size_t size;