[rds-devel] [PATCH] Fix a bug in setting up memory ranges

[Olaf Kirch]

Hi Rick,

On Saturday 05 January 2008 03:30, Richard Frank wrote:
> The issue with sg_set_page - is that the use of the macro is referencing 
> the sg->offset field before it is set !
> 
> So I put back the old sg->page,offset,length set up to test with - and 
> it works - need to go back and fix the sg_set_page to do the right thing.

Using sg_set_page is a must, otherwise the code won't compile on newer
kernels.

Here's an alternative patch - can you confirm it works for you?

Olaf
-- 
Olaf Kirch  |  --- o --- Nous sommes du soleil we love when we play
okir at lst.de |    / | \   sol.dhoop.naytheet.ah kin.ir.samse.qurax
------------------
From: Olaf Kirch <olaf.kirch at oracle.com>
Subject: [RDS] Fix a bug in setting up memory ranges

Rick Frank discovered a bug I introduced when converting the RDMA
code to use scatterlist acessors. In rds_get_mr, we use sg->offset
before initializing it. This patch should fix this.

Signed-off-by: Olaf Kirch <olaf.kirch at oracle.com>
---
 net/rds/rdma.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

Index: ofa-kernel-1.3/net/rds/rdma.c
===================================================================
--- ofa-kernel-1.3.orig/net/rds/rdma.c
+++ ofa-kernel-1.3/net/rds/rdma.c
@@ -263,10 +263,12 @@ int rds_get_mr(struct rds_sock *rs, char
 
 	mr->r_nents = ret;
 	for (i = 0 ; i < mr->r_nents; i++) {
+		unsigned int offset = args.vec.addr & ~PAGE_MASK;
+
 		sg = &mr->r_sg[i];
 		sg_set_page(sg, pages[i],
-				min_t(unsigned int, args.vec.bytes, PAGE_SIZE - sg->offset),
-				args.vec.addr & ~PAGE_MASK);
+				min_t(unsigned int, args.vec.bytes, offset),
+				PAGE_SIZE - offset);
 
 		args.vec.addr += sg->length;
 		args.vec.bytes -= sg->length;