Re: [PATCH net-next 06/15] net/smc: implement DMB-related operations of loopback-ism
From: Wen Gu
Date: Mon Feb 19 2024 - 20:55:42 EST
On 2024/2/16 22:13, Wenjia Zhang wrote:
On 11.01.24 13:00, Wen Gu wrote:
This implements DMB (un)registration and data move operations of
loopback-ism device.
Signed-off-by: Wen Gu <guwen@xxxxxxxxxxxxxxxxx>
---
net/smc/smc_cdc.c | 6 ++
net/smc/smc_cdc.h | 1 +
net/smc/smc_loopback.c | 133 ++++++++++++++++++++++++++++++++++++++++-
net/smc/smc_loopback.h | 13 ++++
4 files changed, 150 insertions(+), 3 deletions(-)
diff --git a/net/smc/smc_cdc.c b/net/smc/smc_cdc.c
index 3c06625ceb20..c820ef197610 100644
--- a/net/smc/smc_cdc.c
+++ b/net/smc/smc_cdc.c
@@ -410,6 +410,12 @@ static void smc_cdc_msg_recv(struct smc_sock *smc, struct smc_cdc_msg *cdc)
static void smcd_cdc_rx_tsklet(struct tasklet_struct *t)
{
struct smc_connection *conn = from_tasklet(conn, t, rx_tsklet);
+
+ smcd_cdc_rx_handler(conn);
+}
+
+void smcd_cdc_rx_handler(struct smc_connection *conn)
+{
struct smcd_cdc_msg *data_cdc;
struct smcd_cdc_msg cdc;
struct smc_sock *smc;
diff --git a/net/smc/smc_cdc.h b/net/smc/smc_cdc.h
index 696cc11f2303..11559d4ebf2b 100644
--- a/net/smc/smc_cdc.h
+++ b/net/smc/smc_cdc.h
@@ -301,5 +301,6 @@ int smcr_cdc_msg_send_validation(struct smc_connection *conn,
struct smc_wr_buf *wr_buf);
int smc_cdc_init(void) __init;
void smcd_cdc_rx_init(struct smc_connection *conn);
+void smcd_cdc_rx_handler(struct smc_connection *conn);
#endif /* SMC_CDC_H */
diff --git a/net/smc/smc_loopback.c b/net/smc/smc_loopback.c
index 353d4a2d69a1..f72e7b24fc1a 100644
--- a/net/smc/smc_loopback.c
+++ b/net/smc/smc_loopback.c
@@ -15,11 +15,13 @@
#include <linux/types.h>
#include <net/smc.h>
+#include "smc_cdc.h"
#include "smc_ism.h"
#include "smc_loopback.h"
#if IS_ENABLED(CONFIG_SMC_LO)
#define SMC_LO_V2_CAPABLE 0x1 /* loopback-ism acts as ISMv2 */
+#define SMC_DMA_ADDR_INVALID (~(dma_addr_t)0)
static const char smc_lo_dev_name[] = "loopback-ism";
static struct smc_lo_dev *lo_dev;
@@ -50,6 +52,97 @@ static int smc_lo_query_rgid(struct smcd_dev *smcd, struct smcd_gid *rgid,
return 0;
}
+static int smc_lo_register_dmb(struct smcd_dev *smcd, struct smcd_dmb *dmb,
+ void *client_priv)
+{
+ struct smc_lo_dmb_node *dmb_node, *tmp_node;
+ struct smc_lo_dev *ldev = smcd->priv;
+ int sba_idx, order, rc;
+ struct page *pages;
+
+ /* check space for new dmb */
+ for_each_clear_bit(sba_idx, ldev->sba_idx_mask, SMC_LO_MAX_DMBS) {
+ if (!test_and_set_bit(sba_idx, ldev->sba_idx_mask))
+ break;
+ }
+ if (sba_idx == SMC_LO_MAX_DMBS)
+ return -ENOSPC;
+
+ dmb_node = kzalloc(sizeof(*dmb_node), GFP_KERNEL);
+ if (!dmb_node) {
+ rc = -ENOMEM;
+ goto err_bit;
+ }
+
+ dmb_node->sba_idx = sba_idx;
+ order = get_order(dmb->dmb_len);
+ pages = alloc_pages(GFP_KERNEL | __GFP_NOWARN |
+ __GFP_NOMEMALLOC | __GFP_COMP |
+ __GFP_NORETRY | __GFP_ZERO,
+ order);
+ if (!pages) {
+ rc = -ENOMEM;
+ goto err_node;
+ }
+ dmb_node->cpu_addr = (void *)page_address(pages);
+ dmb_node->len = dmb->dmb_len;
+ dmb_node->dma_addr = SMC_DMA_ADDR_INVALID;
+
+again:
+ /* add new dmb into hash table */
+ get_random_bytes(&dmb_node->token, sizeof(dmb_node->token));
+ write_lock(&ldev->dmb_ht_lock);
+ hash_for_each_possible(ldev->dmb_ht, tmp_node, list, dmb_node->token) {
+ if (tmp_node->token == dmb_node->token) {
+ write_unlock(&ldev->dmb_ht_lock);
+ goto again;
+ }
+ }
+ hash_add(ldev->dmb_ht, &dmb_node->list, dmb_node->token);
+ write_unlock(&ldev->dmb_ht_lock);
+
The write_lock_irqsave()/write_unlock_irqrestore() and read_lock_irqsave()/read_unlock_irqrestore()should be used
instead of write_lock()/write_unlock() and read_lock()/read_unlock() in order to keep the lock irq-safe.
dmb_ht_lock won't be hold in an interrupt or sockirq context. The dmb_{register|unregister},
dmb_{attach|detach} and data_move are all on the process context. So I think write_(un)lock
and read_(un)lock is safe here.
+ dmb->sba_idx = dmb_node->sba_idx;
+ dmb->dmb_tok = dmb_node->token;
+ dmb->cpu_addr = dmb_node->cpu_addr;
+ dmb->dma_addr = dmb_node->dma_addr;
+ dmb->dmb_len = dmb_node->len;
+
+ return 0;
+
+err_node:
+ kfree(dmb_node);
+err_bit:
+ clear_bit(sba_idx, ldev->sba_idx_mask);
+ return rc;
+}
+
+static int smc_lo_unregister_dmb(struct smcd_dev *smcd, struct smcd_dmb *dmb)
+{
+ struct smc_lo_dmb_node *dmb_node = NULL, *tmp_node;
+ struct smc_lo_dev *ldev = smcd->priv;
+
+ /* remove dmb from hash table */
+ write_lock(&ldev->dmb_ht_lock);
+ hash_for_each_possible(ldev->dmb_ht, tmp_node, list, dmb->dmb_tok) {
+ if (tmp_node->token == dmb->dmb_tok) {
+ dmb_node = tmp_node;
+ break;
+ }
+ }
+ if (!dmb_node) {
+ write_unlock(&ldev->dmb_ht_lock);
+ return -EINVAL;
+ }
+ hash_del(&dmb_node->list);
+ write_unlock(&ldev->dmb_ht_lock);
+
+ clear_bit(dmb_node->sba_idx, ldev->sba_idx_mask);
+ kfree(dmb_node->cpu_addr);
+ kfree(dmb_node);
+
+ return 0;
+}
+
static int smc_lo_add_vlan_id(struct smcd_dev *smcd, u64 vlan_id)
{
return -EOPNOTSUPP;
@@ -76,6 +169,38 @@ static int smc_lo_signal_event(struct smcd_dev *dev, struct smcd_gid *rgid,
return 0;
}
+static int smc_lo_move_data(struct smcd_dev *smcd, u64 dmb_tok,
+ unsigned int idx, bool sf, unsigned int offset,
+ void *data, unsigned int size)
+{
+ struct smc_lo_dmb_node *rmb_node = NULL, *tmp_node;
+ struct smc_lo_dev *ldev = smcd->priv;
+
+ read_lock(&ldev->dmb_ht_lock);
+ hash_for_each_possible(ldev->dmb_ht, tmp_node, list, dmb_tok) {
+ if (tmp_node->token == dmb_tok) {
+ rmb_node = tmp_node;
+ break;
+ }
+ }
+ if (!rmb_node) {
+ read_unlock(&ldev->dmb_ht_lock);
+ return -EINVAL;
+ }
+ read_unlock(&ldev->dmb_ht_lock);
+
+ memcpy((char *)rmb_node->cpu_addr + offset, data, size);
+
Should this read_unlock be placed behind memcpy()?
dmb_ht_lock is used to ensure safe access to the DMB hash table of loopback-ism.
The DMB hash table could be accessed by all the connections on loopback-ism, so
it should be protected.
But a certain DMB is only used by one connection, and the move_data process is
protected by conn->send_lock (see smcd_tx_sndbuf_nonempty()), so the memcpy(rmb_node)
here is safe and no race with other.
Thanks!
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