Patch "IB/srp: Fix infinite loop when FMR sg[0].offset != 0" has been added to the 4.8-stable tree

This is a note to let you know that I've just added the patch titled

    IB/srp: Fix infinite loop when FMR sg[0].offset != 0

to the 4.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
ib-srp-fix-infinite-loop-when-fmr-sg.offset-0.patch
and it can be found in the queue-4.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Bart Van Assche <[email protected]>
Date: Mon, 26 Sep 2016 12:58:49 -0700
Subject: IB/srp: Fix infinite loop when FMR sg[0].offset != 0

From: Bart Van Assche <[email protected]>

commit 681cc3608355737c1effebc8145f95c8c3344bc3 upstream.

Avoid that mapping an sg-list in which the first element has a non-zero offset triggers an infinite loop when using FMR. This patch makes the FMR mapping code similar to that of ib_sg_to_pages().

Note: older Mellanox HCAs do not support non-zero offsets for FMR. See also commit 8c4037b501ac ("IB/srp: always avoid non-zero offsets into an FMR").

---
 drivers/infiniband/ulp/srp/ib_srp.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

@@ -1400,7 +1400,9 @@ static int srp_map_sg_entry(struct srp_m
 
 	while (dma_len) {
 		unsigned offset = dma_addr & ~dev->mr_page_mask;
-		if (state->npages == dev->max_pages_per_mr || offset != 0) {
+
+		if (state->npages == dev->max_pages_per_mr ||
+		    (state->npages > 0 && offset != 0)) {
 			ret = srp_map_finish_fmr(state, ch);
 			if (ret)
 				return ret;

@@ -1417,12 +1419,12 @@ static int srp_map_sg_entry(struct srp_m
 	}
 
 	/*
-	 * If the last entry of the MR wasn't a full page, then we need to
+	 * If the end of the MR is not on a page boundary then we need to
 	 * close it out and start a new one -- we can only merge at page
 	 * boundaries.
 	 */
 	ret = 0;
-	if (len != dev->mr_page_size)
+	if ((dma_addr & ~dev->mr_page_mask) != 0)
 		ret = srp_map_finish_fmr(state, ch);
 	return ret;
 }

Patches currently in stable-queue which might be from [email protected] are

queue-4.8/ib-srp-fix-infinite-loop-when-fmr-sg.offset-0.patch queue-4.8/dm-rq-take-request_queue-lock-while-clearing-queue_flag_stopped.patch queue-4.8/ib-core-correctly-handle-rdma_rw_init_mrs-failure.patch queue-4.8/dm-mark-request_queue-dead-before-destroying-the-dm-device.patch queue-4.8/dm-mpath-check-if-path-s-request_queue-is-dying-in-activate_path.patch