Thread (12 messages) 12 messages, 5 authors, 2025-10-08

Re: [PATCH net-next v5 2/2] net/smc: handle -ENOMEM from smc_wr_alloc_link_mem gracefully

From: Mahanta Jambigi <mjambigi@linux.ibm.com>
Date: 2025-10-06 05:55:44
Also in: linux-doc, linux-rdma, linux-s390, lkml

On 29/09/25 7:20 am, Dust Li wrote:
quoted
diff --git a/net/smc/smc_core.h b/net/smc/smc_core.h
index 8d06c8bb14e9..5c18f08a4c8a 100644
--- a/net/smc/smc_core.h
+++ b/net/smc/smc_core.h
@@ -175,6 +175,8 @@ struct smc_link {
	struct completion	llc_testlink_resp; /* wait for rx of testlink */
	int			llc_testlink_time; /* testlink interval */
	atomic_t		conn_cnt; /* connections on this link */
+	u16			max_send_wr;
+	u16			max_recv_wr;
Here, you've moved max_send_wr/max_recv_wr from the link group to individual links.
This means we can now have different max_send_wr/max_recv_wr values on two
different links within the same link group.
Since in Alibaba we doesn't use multi-link configurations, we haven't tested
Does Alibaba always use a single RoCE device for SMC-R? In that case how
redundancy is achieved if that link goes down?
this scenario. Have you tested the link-down handling process in a multi-link
setup?
I did test this after you query & don't see any issues. As Halil
mentioned in worst case scenario one link might perform lesser than the
other, that too if the kcalloc() failed for that link in
smc_wr_alloc_link_mem() & succeeded in subsequent request with reduced
max_send_wr/max_recv_wr size(half).
Otherwise, the patch looks good to me.

Best regards,
Dust
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