[PATCH 5.15 111/148] net/smc: Stop the CLC flow if no link to map buffers on

Greg Kroah-Hartman
2022-09-26T11:25:15Z

From: Wen Gu <guwen@linux.alibaba.com>

[ Upstream commit e738455b2c6dcdab03e45d97de36476f93f557d2 ]

There might be a potential race between SMC-R buffer map and
link group termination.

smc_smcr_terminate_all() | smc_connect_rdma()
--------------------------------------------------------------
| smc_conn_create()
for links in smcibdev |
schedule links down |
| smc_buf_create()
| \- smcr_buf_map_usable_links()
| \- no usable links found,
| (rmb->mr = NULL)
|
| smc_clc_send_confirm()
| \- access conn->rmb_desc->mr[]->rkey
| (panic)

During reboot and IB device module remove, all links will be set
down and no usable links remain in link groups. In such situation
smcr_buf_map_usable_links() should return an error and stop the
CLC flow accessing to uninitialized mr.

Fixes: b9247544c1bc ("net/smc: convert static link ID instances to support multiple links")
Signed-off-by: Wen Gu <guwen@linux.alibaba.com>
Link: https://lore.kernel.org/r/1663656189-32090-1-git-send-email-guwen@linux.alibaba.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/smc/smc_core.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c
index 7401ec67ebcf..2eafefa15a1a 100644
--- a/net/smc/smc_core.c
+++ b/net/smc/smc_core.c
@@ -1980,7 +1980,7 @@ static struct smc_buf_desc *smcr_new_buf_create(struct smc_link_group *lgr,
static int smcr_buf_map_usable_links(struct smc_link_group *lgr,
struct smc_buf_desc *buf_desc, bool is_rmb)
{
- int i, rc = 0;
+ int i, rc = 0, cnt = 0;

/* protect against parallel link reconfiguration */
mutex_lock(&lgr->llc_conf_mutex);
@@ -1993,9 +1993,12 @@ static int smcr_buf_map_usable_links(struct smc_link_group *lgr,
rc = -ENOMEM;
goto out;
}
+ cnt++;
}
out:
mutex_unlock(&lgr->llc_conf_mutex);
+ if (!rc && !cnt)
+ rc = -EINVAL;
return rc;
}

--
2.35.1