This is a note to let you know that I've just added the patch titled
net/smc: add operations to merge sndbuf with peer DMB
to the 6.6-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:
net-smc-add-operations-to-merge-sndbuf-with-peer-dmb.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 691098ba12faec4ee6d6d83b2d1ed0ea30ccf267
Author: Wen Gu <guwen@xxxxxxxxxxxxxxxxx>
Date: Sun Apr 28 14:07:35 2024 +0800
net/smc: add operations to merge sndbuf with peer DMB
[ Upstream commit 4398888268582cb51b69c6ee94f551bb8d37d12f ]
In some scenarios using Emulated-ISM device, sndbuf can share the same
physical memory region with peer DMB to avoid data copy from one side
to the other. In such case the sndbuf is only a descriptor that
describes the shared memory and does not actually occupy memory, it's
more like a ghost buffer.
+----------+ +----------+
| socket A | | socket B |
+----------+ +----------+
| |
+--------+ +--------+
| sndbuf | | DMB |
| desc | | desc |
+--------+ +--------+
| |
| +----v-----+
+--------------------------> memory |
+----------+
So here introduces three new SMC-D device operations to check if this
feature is supported by device, and to {attach|detach} ghost sndbuf to
peer DMB. For now only loopback-ism supports this.
Signed-off-by: Wen Gu <guwen@xxxxxxxxxxxxxxxxx>
Reviewed-by: Wenjia Zhang <wenjia@xxxxxxxxxxxxx>
Reviewed-and-tested-by: Jan Karcher <jaka@xxxxxxxxxxxxx>
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Stable-dep-of: 0541db8ee32c ("net/smc: initialize close_work early to avoid warning")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/include/net/smc.h b/include/net/smc.h
index 9dfe57f3e4f0b..6fef76087b9ed 100644
--- a/include/net/smc.h
+++ b/include/net/smc.h
@@ -79,6 +79,9 @@ struct smcd_ops {
int (*reset_vlan_required)(struct smcd_dev *dev);
int (*signal_event)(struct smcd_dev *dev, struct smcd_gid *rgid,
u32 trigger_irq, u32 event_code, u64 info);
+ int (*support_dmb_nocopy)(struct smcd_dev *dev);
+ int (*attach_dmb)(struct smcd_dev *dev, struct smcd_dmb *dmb);
+ int (*detach_dmb)(struct smcd_dev *dev, u64 token);
};
struct smcd_dev {
diff --git a/net/smc/smc_ism.c b/net/smc/smc_ism.c
index 3623df320de55..61ffc72014013 100644
--- a/net/smc/smc_ism.c
+++ b/net/smc/smc_ism.c
@@ -228,6 +228,46 @@ int smc_ism_register_dmb(struct smc_link_group *lgr, int dmb_len,
#endif
}
+bool smc_ism_support_dmb_nocopy(struct smcd_dev *smcd)
+{
+ /* for now only loopback-ism supports
+ * merging sndbuf with peer DMB to avoid
+ * data copies between them.
+ */
+ return (smcd->ops->support_dmb_nocopy &&
+ smcd->ops->support_dmb_nocopy(smcd));
+}
+
+int smc_ism_attach_dmb(struct smcd_dev *dev, u64 token,
+ struct smc_buf_desc *dmb_desc)
+{
+ struct smcd_dmb dmb;
+ int rc = 0;
+
+ if (!dev->ops->attach_dmb)
+ return -EINVAL;
+
+ memset(&dmb, 0, sizeof(dmb));
+ dmb.dmb_tok = token;
+ rc = dev->ops->attach_dmb(dev, &dmb);
+ if (!rc) {
+ dmb_desc->sba_idx = dmb.sba_idx;
+ dmb_desc->token = dmb.dmb_tok;
+ dmb_desc->cpu_addr = dmb.cpu_addr;
+ dmb_desc->dma_addr = dmb.dma_addr;
+ dmb_desc->len = dmb.dmb_len;
+ }
+ return rc;
+}
+
+int smc_ism_detach_dmb(struct smcd_dev *dev, u64 token)
+{
+ if (!dev->ops->detach_dmb)
+ return -EINVAL;
+
+ return dev->ops->detach_dmb(dev, token);
+}
+
static int smc_nl_handle_smcd_dev(struct smcd_dev *smcd,
struct sk_buff *skb,
struct netlink_callback *cb)
diff --git a/net/smc/smc_ism.h b/net/smc/smc_ism.h
index 0e5e563099ec3..8312c3586d2b3 100644
--- a/net/smc/smc_ism.h
+++ b/net/smc/smc_ism.h
@@ -41,6 +41,10 @@ int smc_ism_put_vlan(struct smcd_dev *dev, unsigned short vlan_id);
int smc_ism_register_dmb(struct smc_link_group *lgr, int buf_size,
struct smc_buf_desc *dmb_desc);
int smc_ism_unregister_dmb(struct smcd_dev *dev, struct smc_buf_desc *dmb_desc);
+bool smc_ism_support_dmb_nocopy(struct smcd_dev *smcd);
+int smc_ism_attach_dmb(struct smcd_dev *dev, u64 token,
+ struct smc_buf_desc *dmb_desc);
+int smc_ism_detach_dmb(struct smcd_dev *dev, u64 token);
int smc_ism_signal_shutdown(struct smc_link_group *lgr);
void smc_ism_get_system_eid(u8 **eid);
u16 smc_ism_get_chid(struct smcd_dev *dev);
