[PATCH] RDMA/siw: Trim size of page array to max size needed

[Bernard Metzler <bmt@xxxxxxxxxxxxxx>]

siw tries sending all parts of an iWarp wire frame in one socket
send operation. If user data can be send without copy, user data
pages for one wire frame are referenced in an fixed size page array.
The size of this array can be made 2 elements smaller, since it
does not reference iWarp header and trailer crc. Trimming
the page array reduces the affected siw_tx_hdt() functions frame
size, staying below 1024 bytes. This avoids the following
compile-time warning:

 drivers/infiniband/sw/siw/siw_qp_tx.c: In function 'siw_tx_hdt':
 drivers/infiniband/sw/siw/siw_qp_tx.c:677:1: warning: the frame
 size of 1040 bytes is larger than 1024 bytes [-Wframe-larger-than=]

Fixes: b9be6f18cf9e ("rdma/siw: transmit path")
Reported-by: ionut_n2001@xxxxxxxxx
Link: https://bugzilla.kernel.org/show_bug.cgi?id=218375
Signed-off-by: Bernard Metzler <bmt@xxxxxxxxxxxxxx>
---
 drivers/infiniband/sw/siw/siw_qp_tx.c | 29 +++++++++++++++------------
 1 file changed, 16 insertions(+), 13 deletions(-)

diff --git a/drivers/infiniband/sw/siw/siw_qp_tx.c b/drivers/infiniband/sw/siw/siw_qp_tx.c
index 64ad9e0895bd..7ffc91bac606 100644
--- a/drivers/infiniband/sw/siw/siw_qp_tx.c
+++ b/drivers/infiniband/sw/siw/siw_qp_tx.c
@@ -432,7 +432,7 @@ static int siw_tx_hdt(struct siw_iwarp_tx *c_tx, struct socket *s)
 	struct siw_wqe *wqe = &c_tx->wqe_active;
 	struct siw_sge *sge = &wqe->sqe.sge[c_tx->sge_idx];
 	struct kvec iov[MAX_ARRAY];
-	struct page *page_array[MAX_ARRAY];
+	struct page *page_array[MAX_ARRAY-2];
 	struct msghdr msg = { .msg_flags = MSG_DONTWAIT | MSG_EOR };
 
 	int seg = 0, do_crc = c_tx->do_crc, is_kva = 0, rv;
@@ -491,7 +491,6 @@ static int siw_tx_hdt(struct siw_iwarp_tx *c_tx, struct socket *s)
 
 		while (sge_len) {
 			size_t plen = min((int)PAGE_SIZE - fp_off, sge_len);
-			void *kaddr;
 
 			if (!is_kva) {
 				struct page *p;
@@ -503,14 +502,12 @@ static int siw_tx_hdt(struct siw_iwarp_tx *c_tx, struct socket *s)
 					rv = -EFAULT;
 					goto done_crc;
 				}
-				page_array[seg] = p;
-
 				if (!c_tx->use_sendpage) {
-					void *kaddr = kmap_local_page(p);
+					void *pa = kmap_local_page(p);
 
 					/* Remember for later kunmap() */
 					kmap_mask |= BIT(seg);
-					iov[seg].iov_base = kaddr + fp_off;
+					iov[seg].iov_base = pa + fp_off;
 					iov[seg].iov_len = plen;
 
 					if (do_crc)
@@ -518,12 +515,17 @@ static int siw_tx_hdt(struct siw_iwarp_tx *c_tx, struct socket *s)
 							c_tx->mpa_crc_hd,
 							iov[seg].iov_base,
 							plen);
-				} else if (do_crc) {
-					kaddr = kmap_local_page(p);
-					crypto_shash_update(c_tx->mpa_crc_hd,
-							    kaddr + fp_off,
-							    plen);
-					kunmap_local(kaddr);
+				} else {
+					page_array[seg] = p;
+					if (do_crc) {
+						void *pa = kmap_local_page(p);
+
+						crypto_shash_update(
+							c_tx->mpa_crc_hd,
+							pa + fp_off,
+							plen);
+						kunmap_local(pa);
+					}
 				}
 			} else {
 				/*
@@ -545,7 +547,8 @@ static int siw_tx_hdt(struct siw_iwarp_tx *c_tx, struct socket *s)
 			data_len -= plen;
 			fp_off = 0;
 
-			if (++seg >= (int)MAX_ARRAY) {
+			if (++seg >= (int)MAX_ARRAY ||
+			    (c_tx->use_sendpage && seg >= (int)MAX_ARRAY-2)) {
 				siw_dbg_qp(tx_qp(c_tx), "to many fragments\n");
 				siw_unmap_pages(iov, kmap_mask, seg-1);
 				wqe->processed -= c_tx->bytes_unsent;
-- 
2.38.1