[PATCH V2] rds: ib: force endiannes annotation

From: Nicholas Mc Guire
Date: Mon Apr 29 2019 - 23:19:04 EST


While the endiannes is being handled correctly as indicated by the comment
above the offending line - sparse was unhappy with the missing annotation
as be64_to_cpu() expects a __be64 argument. To mitigate this annotation
all involved variables are changed to a consistent __le64 and the
conversion to uint64_t delayed to the call to rds_cong_map_updated().

Signed-off-by: Nicholas Mc Guire <hofrat@xxxxxxxxx>
---

Problem located by an experimental coccinelle script to locate
patters that make sparse unhappy (false positives):
net/rds/ib_recv.c:827:23: warning: cast to restricted __le64

V2: Edward Cree <ecree@xxxxxxxxxxxxxx> rejected the need for using __force
here - instead solve the sparse issue by updating all of the involved
variables - which results in an identical binary as well without using
the __force "solution" to the sparse warning. Thanks !

Patch was compile-tested with: x86_64_defconfig + INFINIBAND=m, RDS_RDMA=m

Patch was verified not to change the binary by diffing the
generated object code before and after applying the patch.

Patch is against 5.1-rc6 (localversion-next is 20190429)

net/rds/ib_recv.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/net/rds/ib_recv.c b/net/rds/ib_recv.c
index 7055985..8946c89 100644
--- a/net/rds/ib_recv.c
+++ b/net/rds/ib_recv.c
@@ -772,7 +772,7 @@ static void rds_ib_cong_recv(struct rds_connection *conn,
unsigned long frag_off;
unsigned long to_copy;
unsigned long copied;
- uint64_t uncongested = 0;
+ __le64 uncongested = 0;
void *addr;

/* catch completely corrupt packets */
@@ -789,7 +789,7 @@ static void rds_ib_cong_recv(struct rds_connection *conn,
copied = 0;

while (copied < RDS_CONG_MAP_BYTES) {
- uint64_t *src, *dst;
+ __le64 *src, *dst;
unsigned int k;

to_copy = min(RDS_FRAG_SIZE - frag_off, PAGE_SIZE - map_off);
@@ -824,9 +824,7 @@ static void rds_ib_cong_recv(struct rds_connection *conn,
}

/* the congestion map is in little endian order */
- uncongested = le64_to_cpu(uncongested);
-
- rds_cong_map_updated(map, uncongested);
+ rds_cong_map_updated(map, le64_to_cpu(uncongested));
}

static void rds_ib_process_recv(struct rds_connection *conn,
--
2.1.4